TheCodeBreakers (0)

Some of the things you will learn in THE CODEBREAKERS 
 
•  How secret   Japanese  messages were decoded in Washington hours before Pearl   Harbor . 
•  How  German codebreakers helped usher in the Russian Revolution . 
•  How John F. Kennedy  escaped capture  in the Pacific because the Japanese failed to solve a 
simple cipher . 
•  How codebreaking determined a presidential election,  convicted  an underworld  syndicate 
head, won the  battle of Midway , led to cruel Allied defeats in North Africa , and broke up a vast 
Nazi spy ring. 
•  How one American became the world's most  famous  codebreaker, and another became the 
world's greatest . 
•  How codes and codebreakers operate today   within  the secret agencies of the U.S. and Russia . 
•  And incredibly much more. 
"For many evenings of gripping  reading , no better choice can be made than  this book." 
— Christian   Science   Monitor  
 
THE 
Codebreakers 
 
The Story of Secret Writing 
 
By DAVID KAHN  
( abridged by the author ) 
 
A SIGNET BOOK from 
NEW AMERICAN LIBRARV
TIMES MIRROR  
 
Copyright © 1967, 1973 by David Kahn 
All rights reserved. 
No part of this book may be reproduced or transmitted 
in any form or by any means , electronic or  mechanical , 
including  photocopying, recording or by any information 
storage  and retrieval system,  without permission  in writing 
from the publisher . For information address 
The Macmillan Company, 866 Third Avenue, New York , 
New York 10022. 
Library of Congress Catalog Card Number: 63-16109 
Crown copyright is acknowledged for the following illustrations 
from Great Britain 's Public  Record  Office: 
S.P. 53/18, no. 55, the Phelippes forgery, 
and P.R.O. 31/11/11, the Bergenroth reconstruction . 
Published by arrangement with The Macmillan Company 
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REGISTERED TRADEMARK---MARCA REGISTBADA 
HECHO EN CHICAGO , U.S.A. 
SIGNET, SIGNET CLASSICS, SIGNETTE,  MENTOR AND PLUME BOOKS  
are published by The New American Library, Inc., 
1301 Avenue of the Americas , New York, New York 10019 
FIRST PRINTING,  FEBRUARY , 1973 
PRINTED IN THE UNITED STATES OF AMERICA 
 
To my Parents  
and my Grandmother 
 
Contents 
A Note  on the Abridged  Version
Preface
A Few Words
1.  One Day of  Magic : I
2.  One Day of Magic: II
3.  The First 3,000  Years
4.  The Rise  of the  West
5.  On the  Origin of a  Species
6.  The Era of the Black Chambers
7.  The Contribution of the Dilettantes
8.   Room  40
9.  A War of Intercepts
10.  Two Americans
11.  Secrecy for  Sale
12.   Duel in the Ether: I
13.  Duel in the Ether: II
14.  Censors, Scramblers, and Spies
15.  The Scrutable Orientals
16.  PYCCKAJI Kranrojioras
17.  N.S.A.
18.  Heterogeneous Impulses
19.  Ciphers in the Past  Tense
20.  The  Anatomy  of Cryptology
Suggestions for Further  Reading 
Index
A Note on the Abridged Version 
 
MANY PEOPLE have  urged  me to put out a paperback edition  of The Codebreakers.  Here it is. 
It comprises about a third of the  original . This was as big as the publishers and I could  make it and  still  
keep the  price  within  reason . 
In cutting the book, I retained  mainly stories  about how codebreaking has  affected history, particularly  
in World War II, and major   names and stages in the history of cryptology. I eliminated all source notes and 
most of the technical matter , as well as material peripheral to strict codebreaking  such  as biographies, the 
invention  of secondary cipher systems, and miscellaneous uses of various systems. 
I had no space  for new material, but I did correct the errors reported to me and updated a few items . 
The chapters  have been slightly rearranged. 
Readers wanting to  know more about a specific point should consult the text and notes of the original. 
If any reader wishes to  offer any corrections or to tell  me of his own  experiences in this  field , I would 
be very grateful if he would send   them  to me. 
—D.K. 
Windsor Gate  
Great Neck, New York 
 
Preface 
 
CODEBREAKING is the most important  form of secret intelligence in the world today. It produces much more 
and much more trustworthy information than spies, and this intelligence exerts great influence upon the 
policies of governments. Yet it has  never  had a chronicler. 
It badly  needs  one. It has been  estimated that cryptanalysis saved a year of war in the Pacific, yet the 
histories give it but  passing   mention . Churchill 's great history of World War II has been cleaned of every 
single reference  to Allied communications intelligence except one (and that based on the American Pearl 
Harbor investigation), although Britain  thought  it vital enough to assign 30,000 people to the work . The 
intelligence history of World War II has never been written. All this gives a distorted view of why things 
happened . Furthermore , cryptology itself can  benefit , like  other spheres of human endeavor, from knowing 
its major trends , its great men, its errors made and lessons learned. 
I have tried in this book to write a serious  history of cryptology. It is primarily a report to the public on 
the important  role that cryptology has played, but it may also orient cryptology with regard to its past and 
alert historians to the sub rosa influence of cryptanalysis. The book seeks to  cover the entire history of 
cryptology. My  goal  has been twofold: to narrate the  development  of the various methods of  making and 
breaking codes and ciphers, and to tell how  these methods have affected men. 
When I began this book, I, like other well-informed amateurs, knew about all that had been published 
on the history of cryptology in books on the  subject . How little we really knew! Neither we nor any 
professionals realized that many  valuable   articles lurked in scholarly journals , or had induced any 
cryptanalysts to tell their stories for publication, or had tapped the vast treasuries of  documentary  material, 
or had tried to take a long view and ask some  questions that now appear  basic . I believe it to be true that, 
from the point of view of the material previously published in books on cryptology, what is new in this 
book is 85 to 90 per cent . 
Yet it is not exhaustive. A foolish secrecy still clothes much of World War II cryptology—though I 
believe the outlines of the achievements are  known —and to tell just that story in full would  require a book 
the size  of this.  Even  in, say, the  18th century , the unexplored manuscript material is very great. 
Nor is this a textbook . I have sketched a few methods of  solution . For some readers even this will be too 
much; them I advise skip this material. They will not have a full understanding  of what is going  on, but that 
will not cripple their comprehension of the stories. For readers who want more detail on these methods, I 
recommend, in the  rear  of this book, some other  works  and  membership in the American Cryptogram 
Association . 
In my writing, I have tried to adhere to two principles. One was to use  primary   sources as much as 
possible. Often it could not be  done  any other way,  since   nothing  had been published on a  particular matter. 
The other principle was to try to make certain that I did not give cryptology sole and total credit for 
winning  a battle or making possible a diplomatic coup or whatever happened if, as was usual, other factors 
played a role. Narratives which make it appear as if every event in history turned upon the subject under 
discussion are not history but journalism. They are especially prevalent in spy stories, and cryptology is not 
immune . The only other book- length  attempt to survey the history of cryptology, the late Fletcher Pratt's 
Secret and Urgent , published in 1939, suffers from a severe  case of this special pleading. Pratt writes 
thrillingly— perhaps  for that very reason—but his failure  to  consider the other factors, together with his 
errors and omissions, his false generalizations based on no  evidence , and his unfortunate predilection for 
inventing facts vitiate his work as any kind of a history. ( Finding  this out was disillusioning, for it was this 
book, borrowed from the Great Neck Library, that interested me in cryptology.) I think that although trying 
to  balance the story with the other factors may detract a little from the immediate thrill, it charges it with 
authenticity and  hence makes for long-lasting  interest : for this is how things really happened. 
In the same  vein, I have not made up any conversations, and my speculations about things not a matter 
of record have been marked as such in the notes in the full-length version. I have documented all important 
facts, except that in a few cases I have had to  respect the wishes of my sources for anonymity. 
The original publisher submitted the manuscript to the  Department  of  Defense  on  March  4, 1966, which 
requested three  minor deletions—to all of which I acceded—before releasing the manuscript for 
publication. 
DAVID KAHN 
Windsor Gate 
Great Neck, New York 
Paris  
A Few Words 
 
 
EVERY TRADE has its  vocabulary . That of cryptology is simple, but even so a familiarity with its terms  
facilitates understanding. A glossary may also  serve as a handy  reference. The definitions in this one are 
informal  and ostensive.  Exceptions  are ignored and the  host  of minor terms are not defined—the text covers 
these when they  come  up. 
The plaintext is the message that will be put into secret form. Usually the plaintext is in the  native  
tongue of the communicators. The message may be hidden  in two basic  ways . The methods of 
steganography conceal the very existence of the message.  Among them are invisible inks and microdots 
and arrangements in which, for example, the first letter  of each word in an apparently innocuous text spells 
out the  real  message. (When steganography is applied to  electrical communications, such as a method that 
transmits a long  radio  message in a single short spurt, it is called transmission security .) The methods of 
cryptography, on the other hand , do not conceal the presence of a secret message but  render it 
unintelligible to outsiders by various transformations of the plaintext. 
Two basic transformations  exist . In transposition, the letters  of the plaintext are jumbled; their normal 
order  is disarranged. To  shuffle  secret into ETCRSE is a transposition. In  substitution , the letters of the 
plaintext are replaced by other letters, or by numbers or  symbols . Thus secret might become 19 5 3 18 5 20, 
or XIWOXY in a more complicated system. In transposition, the letters retain  their identities— the two e's of 
secret are still  present in ETCRSE—but they  lose their positions , while in substitution the letters retain their 
positions but lose their identities. Transposition and substitution may be combined. 
Substitution systems are much more  diverse and important than transposition systems. They rest on the 
concept  of the cipher alphabet . This is the list of equivalents used to transform the plaintext into the secret 
form. A sample cipher alphabet might be: 
 
plaintext letters  abcdefghijklm 
cipher letters  
LBQACSRDTOFVM 
plaintext letters nopqrstuvwxyz 
cipher letters 
HWIJXGKYUNZEP 
 
This graphically indicates that the letters of the plaintext are to be replaced by the cipher letters beneath 
them, and vice versa. Thus, enemy would become  CHCME , and swc would  reduce  to foe. A set of such 
correspondences is still called a "cipher alphabet" if the plaintext letters are in mixed order, or even if they 
are missing , because cipher letters always imply plaintext letters. 
Sometimes such an alphabet will provide multiple substitutes for a letter. Thus plaintext e, for 
example, instead of always being replaced by, say, 16, will be replaced by any one of the  figures 16, 74, 35, 
21. These alternates are called homophones. Sometimes a cipher alphabet will include symbols that mean  
nothing and are intended to confuse interceptors; these are called nulls. 
As long as only one cipher alphabet is in use, as above , the system is called monoalpbabetic. When, 
however , two or more cipher alphabets are employed in some kind of prearranged pattern, the system 
becomes polyalphabetic. A simple form of polyalphabetic substitution would be to add another cipher 
alphabet under the one  given  above and then to use the two in  rotation , the first alphabet for the first 
plaintext letter, the second for the second, the first again for the third plaintext letter, the second for the 
fourth, and so on. Modern cipher machines produce polyalphabetic ciphers that employ   millions  of cipher 
alphabets. 
Among the systems of substitution,  code  is distinguished from cipher. A code  consists  of thousands of 
words,  phrases , letters, and syllables with the codewords or code-numbers (or, more generally, the 
codegroups) that replace these plaintext elements . 
 
plaintext  
codeword 
emplacing   DVAP 
employ  
DVBO 
en-  
DVCN 
enable  
DVDM 
enabled 
DVEL 
enabled to 
DVFK 
 
This means, of course , that DVDM replaces enable. If the plaintext and the code elements both  run in 
alphabetical or  numerical  order, as above, the code is a one-part code, because a single book serves for 
both en- and decoding. If, however, the code equivalents stand in mixed order opposite their plaintext 
elements, like this 
 
Plaintext codenumber 
shield (for)  51648 
shielded 
07510 
shielding 
10983 
shift (s) 
43144 
ship  
35732 
ships 
10762 
 
the code is a two-part code, because a second section , in which the code elements are in  regular  order, is 
required  for decoding: 
 
codenumber  
plaintext 
10980 was 
not 
10981 spontaneous 
(ly) 
 
10983 
shielding  
10986 
April 13  
10988 
withdrawn from  
10990 
acknowledge 
 
In a sense , a code comprises a gigantic cipher alphabet, in which the basic plaintext  unit  is the word or 
the phrase ; syllables and letters are supplied mainly to  spell out words not present in the code. In ciphers, 
on the other hand, the basic unit is the letter, sometimes the letter- pair  (digraph or bigram), very rarely 
larger groups of letters (polygrams). The substitution and transposition systems illustrated above are 
ciphers.  There  is no  sharp theoretical dividing line  between  codes and ciphers; the latter  shade into the 
former as they  grow larger. But in modern practice the  differences  are usually quite marked. Sometimes the 
two are distinguished by saying that ciphers operate on plaintext  units  of regular length (all single letters or 
all groups of, say, three letters), whereas codes operate on plaintext groups of variable length (words, 
phrases, individual  letters, etc.). A more penetrating and useful distinction is that code operates on 
linguistic entities, dividing its raw material into meaningful elements like words and syllables, where as 
cipher does not—cipher will split the t from the h in the, for example. 
For 450 years, from about  1400  to about 1850, a system that was  half  a code and half a cipher 
dominated cryptography. It usually had a separate cipher alphabet with homophones and a codelike list of 
names, words, and syllables. This list, originally just of names, gave  the system its name: nomenclator. 
Even though late in its life some nomenclators grew larger than some modern codes, such systems are still 
called "nomenclators" if they  fall within this historical period . An odd characteristic is that nomenclators 
were always written on large folded sheets of  paper , whereas modern codes are almost invariably in book 
or  booklet  form. The commercial code is a code used in business primarily to save on  cable tolls; though 
some are compiled for private  firms , many others  are  sold  to the public and therefore  provide no real 
secrecy. 
Most ciphers employ a key, which specifies such things as the arrangement of letters within a cipher 
alphabet, or the pattern of shuffling in a transposition, or the settings on a cipher  machine . If a word or 
phrase or number serves as the key, it is naturally called the keyword or keyphrase or keynumber. Keys 
exist within a general system and control that system's variable elements. For example, if a polyalphabetic 
cipher provides 26 cipher alphabets, a keyword might  define the half dozen or so that are to be used in a 
particular message. 
Codewords or codenumbers can be subjected to transposition or substitution just like any other group 
of letters or numbers—the transforming  processes do not ask that the texts given to them be intelligible. 
Code that has not yet undergone such a  process —called superencipherment —or which has been 
deciphered from it is called placode, a shortening of " plain  code." Code that has been transformed is called 
encicode, from "enciphered code." 
To  pass  a plaintext  through these transformations is to encipher or encode it, as the case may be. What 
comes out of the transformation is the ciphertext or the codetext. The final secret message,  wrapped  up 
and sent , is the cryptogram. (The term  "ciphertext" emphasizes the result  of encipherment more, while 
"cryptogram" emphasizes the  fact of transmission more; it is analogous to " telegram .") To decipher or 
decode is for the persons legitimately possessing the key and system to  reverse the transformations and 
bare  the original message. It  contrasts with cryptanalyze, in which persons who do not possess the key or 
system— a third  party , the "enemy"—break down or solve the cryptogram. The  difference  is, of course, 
crucial . Before about 1920, when the word cryptanalysis was coined to mean the methods of breaking 
codes and ciphers, "decipher" and "decode" served in both senses (and  occasionally still do), and in 
quotations  where they are used in the sense of solve, they are retained if they will not confuse. Sometimes 
cryptanalysis is called codebreaking; this includes solving ciphers. The original intelligible text that 
emerges from either decipherment or cryptanalysis is again called plaintext. Messages sent without 
encipherment are cleartext or in clear , though they are sometimes called in plain language . 
Cryptology is the science that embraces cryptography and cryptanalysis, but the term "cryptology" 
sometimes loosely designates the entire  dual  field of both rendering  signals  secure and extracting 
information from them. This broader field has grown to include many new  areas ; it encompasses, for 
example, means to deprive the enemy of information obtainable by  studying  the  traffic   patterns  of radio 
messages, and means of obtaining information from  radar  emissions. An  outline of this larger field, with its 
opposing parts placed opposite one another, and with a few of the methods of each part given in 
parentheses, would be: 
 
SIGNAL   SECURITY                                            SIGNAL INTELLIGENCE 
 
Communication Security 
 
Communication Intelligence
Steganography (invisible inks, op n 
e
Interception and Direction-Finding 
codes, messages in hollow  heels) 
and Transmission Security (spurt 
radio systems)  
Traffic Security  ( call - sign   changes , 
Traffic   Analysis    (direction-finding 
dummy messages, radio silence) 
fixes , message-flow  studies , radio- 
fingerprinting)  
 
Cryptography   (codes  and  ciphers,  
Cryptanalysis 
ciphony, cifax) 
 
Electronic Security 
 
Electronic Intelligence
Emission  Security ( shifting of ra- 
Electronic Reconnaissance (e v
a es- 
dar frequencies)   
 
dropping on radar emissions) 
Counter -Countermeasures (" look - 
Countermeasures (jamming, false 
ing-through" jammed radar)  radar echoes) 
 
This book employs certain typographic conventions for simplicity and economy . Plaintext is always set 
lower case; when it occurs in the running text (as opposed to its occurrence in the diagrams ), it is also in 
italics . Cipher-text or codetext is set in SMALL CAPS  in the text, keys in LARGE CAPS. They are 
distinguished in the diagrams by labels. Cleartext and translations of foreign-language plaintext are in 
roman  within  quotation   marks . The sound  of a letter or  syllable or word, as distinguished from its written 
form, is placed within diagonals, according to the  convention widely followed in linguistics; thus /t/ refers 
to the unvoiced stop normally represented by that letter and not to the graphic   symbol  t. 
D. K. 
 
 
1. One Day of Magic:  I 
 
AT 1:28 on the morning of December 7, 1941, the big ear of the Navy's 
radio station on Bainbridge Island near Seattle trembled to vibrations in 
the ether. A message was coming through on the Tokyo -Washington 
circuit . It was addressed to the Japanese embassy, and Bainbridge 
reached up and snared it as it flashed overhead. The message was short, 
and its radiotelegraph transmission took only nine minutes. Bainbridge 
had it all by 1:37. 
The station's personnel punched the intercepted message on a 
teletype tape, dialed a number on the teletypewriter exchange , and when 
the connection had been made, fed the tape into a mechanical 
transmitter that gobbled it up at 60 words per minute . 
The intercept reappeared on a page-printer in Room 1649 of the Navy 
Department building on Constitution Avenue in Washington, D.C. What 
went on in this room, tucked for security's sake at the end of the first 
deck 's sixth wing , was one of the most closely guarded secrets of the 
American government . For it was in here—and in a similar War 
Department room in the Munitions Building next door —that the United 
States peered into the most confidential thoughts and plans of its 
possible enemies by shredding the coded wrappings of their dispatches. 
Room 1649 housed OP-20-GY, the cryptanalytic section of the Navy's 
cryptologic organization, OP-20-G. The page-printer stood beside the 
desk of the GY watch officer. It rapped out the intercept in an original and 
a carbon copy on yellow and pink teletype paper just like news on a city 
room wireservice ticker. The watch officer, Lieutenant (j.g.) Francis M. 
Brotherhood, U.S.N.R., a curly-haired, brown - eyed six- footer , saw 
immediately from indicators that the message bore for the guidance of 
Japanese code clerks that it was in the top Japanese cryptographic 
system. 
This was an extremely complicated machine cipher which American 
cryptanalysts called  PURPLE . Led by William F. Friedman , Chief  
Cryptanalyst of the Army Signal Corps , a team of codebreakers had 
solved Japan 's enciphered dispatches, deduced the nature of the 
mechanism that would effect those letter transformations, and 
painstakingly built up an apparatus that cryptographically duplicated 
the Japanese machine. The Signal Corps had then constructed several  
additional PURPLE machines, using a hodgepodge of manufactured parts, 
and had given one to the Navy. Its three components rested now on a 
table in Room 1649: an electric typewriter for input; the cryptographic 
assembly proper , consisting of a plugboard, four electric coding rings , 
and associated wires and switches, set on a wooden frame ; and a 
printing unit for output. To this precious contraption, worth quite 
literally more than its weight in gold , Brotherhood carried the intercept. 
He flicked the switches to the key of December 7. This was a 
rearrangement, according to a pattern ascertained months ago, of the 
key of December 1, which OP-20-QY had recovered. Brotherhood typed 
out the coded message. Electric impulses raced through the maze of 
wires, reversing the intricate enciphering process. In a few minutes, he 
had the plaintext before him. 
It was in Japanese. Brotherhood had taken some of the orientation 
courses in that difficult language that the Navy gave to assist its 
cryptanalysts. He was in no sense a translator , however, and none was 
on duty next door in OP-20-GZ, the translating section. He put a red 
priority sticker on the decode and hand-carried it to the Signal 
Intelligence Service , the Army counterpart of OP-20-O, where he knew 
that a translator was on overnight duty. Leaving it there, he returned to 
OP-20-G. By now it was after 5 a.m. in Washington—the message having  
lost three hours as it passed through three time zones in crossing the 
continent . 
The S.I.S translator rendered the Japanse as: "Will the Ambassador 
please submit to the United States Government (if possible to the 
Secretary of State) our reply to the United States at 1:00 p.m. on the 7th, 
your time." The —"reply" referred to had been transmitted by Tokyo in 14 
parts over the past 18½  hours, and Brotherhood had only recently 
decrypted the 14th part on the PURPLE machine. It had come out in the 
English in which Tokyo had framed it, and its ominous final sentence 
read: "The Japanese Government regrets to have to notify hereby the 
American Government that in view of the attitude of the American 
Government it cannot but consider that it is impossible to reach an 
agreement through further negotiations ." Brotherhood had set it by for 
distribution early in the morning. 
The translation of the message directing delivery at one o' clock had 
not yet come back from S.I.S. when Brotherhood was relieved at 7 a.m., 
and he told his relief, Lieutenant (j.g.) Alfred V. Pering, about it. Half an 
hour later , Lieutenant Commander Alwin D. Kramer , the Japanese-
language expert who headed GZ and delivered the intercepts, arrived . He 
saw at once that the all-important conclusion of the long Japanese 
diplomatic note had come in since he had distributed the 13 previous  
parts the night before. He prepared a smooth copy from the rough decode 
and had his clerical assistant, Chief Yeoman H. L. Bryant , type up the 
usual 14 copies. Twelve of these were distributed by Kramer and his 
opposite number in S.I.S. to the President , the secretaries of State, War, 
and Navy, and a handful of top-ranking Army and Navy officers. The two 
others were file copies. This decode was part of a whole series of 
Japanese intercepts, which had long ago been given a collective 
codename, partly for security, partly for ease of reference, by a previous 
director of naval intelligence, Rear Admiral Walter S. Anderson . Inspired, 
no doubt , by the mysterious daily production of the information and by 
the aura of sorcery and the occult that has always enveloped cryptology, 
he called it MAGIC. 
When Bryant had finished , Kramer sent S.I.S. its seven copies, and at 
8 o'clock took a copy to his superior , Captain Arthur H. McCollum , head 
of the Far Eastern Section of the Office of Naval Intelligence. 
 
From: Tokyo 
To:   Washington 
December 7, 1941 
Purple (Urgent - Very Important) 
#907. 
To be handled in goverment code. 
Re: my #902a. 
Will the Ambaagador please submit to the United States 
Government (If possible to the Secretary of State) our reply to 
the United States at 1:00 p.m. on the 7th, your time. 
 
a - JD-1:7143 - text of Japanese reply. 
MAGIC'S solution of the Japanese one o'clock delivery message 
 
He then busied himself in his office, working on intercepted traffic, 
until 9:30, when he left to deliver the 14th part of Tokyo's reply to 
Admiral Harold F. Stark , the Chief of Naval Operations, to the White 
House, and to Frank Knox, the Secretary of the Navy. Knox was meeting  
at 10 a.m. that Sunday morning in the State Department with Secretary 
of War Henry L. Stimson and Secretary of State Cordell Hull to discuss  
the critical nature of the American negotiations with Japan, which, they 
knew from the previous 13 parts, had virtually reached an impasse. 
Kramer returned to his office about 10:20, where the translation of the 
message referring to the one o'clock delivery had arrived from S.I.S. while 
he was on his rounds . 
Its import crashed in upon him at once. It called for the rupture of 
Japan's negotiations with the United States by a certain deadline . The 
hour set for the Japanese ambassadors to deliver the notification—1 p.m. 
on a Sunday—was highly unusual . And, as Kramer had quickly 
ascertained by drawing a navigator's time circle , 1 p.m. in Washington 
meant 7:30 a.m. in Hawaii and a couple of hours before dawn in the 
tense Far East around Malaya, which Japan had been threatening with 
ships and troops. 
Kramer immediately directed Bryant to insert the one o'clock message 
into the reddish-brown looseleaf cardboard folders in which the MAGIC 
intercepts were bound . He included several other intercepts, adding one 
at the last minute, then slipped the folders into the leather briefcases, 
zipped these shut , and snapped their padlocks. Within ten minutes he 
was on his way. 
He went first to Admiral Stark's office, where a conference was in 
session, and indicated to McCollum, who took the intercept from him, 
the nature of the message and the significance of its timing. McCollum 
grasped it at once and disappeared into Stark's office. Kramer wheeled 
and hurried down the passageway. He emerged from the Navy 
Department building and turned right on Constitution Avenue, heading  
for the meeting in the State Department four blocks away . The urgency of 
the situation washed over him again, and he began to move on the 
double . 
 
This moment, with Kramer running through the empty streets of 
Washington bearing his crucial intercept, an hour before sleepy code 
clerks at the Japanese embassy had even deciphered it and an hour 
before the Japanese planes roared off the carrier flight decks on their 
treacherous mission , is perhaps the finest hour in the history of 
cryptology. Kramer ran while an unconcerned nation slept late, ignored 
aggression in the hope that it would go away, begged the hollow gods of 
isolationism for peace , and refused to entertain—except humorously—the 
possibility that the little yellow men of Japan would dare attack the 
mighty United States. The American cryptanalytic organization swept  
through this miasma of apathy to reach a peak of alertness and 
accomplishment unmatched on that day of infamy by any other agency  
in the United States. That is its great achievement , and its glory. 
Kramer's sprint symbolizes it. 
Why, then, did it not prevent Pearl Harbor? Because Japan never sent 
any message saying anything like "We will attack Pearl Harbor." It was 
therefore impossible for the cryptanalysts to solve one. Messages had 
been intercepted and read in plenty dealing with Japanese interest in 
warship movements into and out of Pearl Harbor, but these were 
evaluated by responsible intelligence officers as on a par with the many 
messages dealing with American warships in other ports and the Panama  
Canal . The causes of the Pearl Harbor disaster are many and complex , 
but no one has ever laid any of whatever blame there may be at the doors  
of OP-20-G or S.I.S. On the contrary, the Congressional committee that 
investigated the attack praised them for fulfilling their duty in a manner  
that "merits the highest commendation." 
As the climax of war rushed near, the two agencies— together the 
most efficient and successful codebreaking organization that had ever 
existed—scaled heights of accomplishment greater than any they had 
ever achieved. The Congressional committee, seeking the responsibility 
for the disaster, exposed their activity on almost a minute-by-minute 
basis . For the first time in history, it photographed in fine-grained detail 
the operation of a modern code-breaking organization at a moment of 
crisis . This is that film . It depicts OP-20-G and S.I.S. in the 24 hours 
preceding the Pearl Harbor attack, with the events of the past as 
prologue. It is the story of one day of MAGIC. 
 
The two American cryptanalytic agencies had not sprung full-blown 
into being like Athena from the brow of Zeus. The Navy had been solving 
at least the simpler Japanese diplomatic and naval codes in Rooms 1649 
and 2646 on the "deck" above since the 1920s . The Army's 
cryptanalytical work during the 1920s was centered in the so-called 
American Black Chamber under Herbert O. Yardley, who had organized 
it as a cryptologic section of military intelligence in World War I. It was 
maintained in secrecy in New York jointly by the War and State 
departments, and perhaps its greatest achievement was its 1920 solution 
of Japanese diplomatic codes. At the same time, the Army's cryptologic 
research and code-compiling functions were handled by William 
Friedman, then as later a civilian employee of the Signal Corps. In 1929, 
Henry L. Stimson, then Secretary of State, withdrew State Department 
support from the Black Chamber on ethical grounds , dissolving it. The 
Army decided to consolidate and enlarge its codemaking and 
codebreaking activities . Accordingly, it created the Signal Intelligence 
Service, with Friedman as chief, and, in 1930, hired three junior 
cryptanalysts and two clerks. 
The following year, a Japanese general suddenly occupied Manchuria 
and set up a puppet Manchu emperor , and the government of the island 
empire of Nippon fell into the hands of the militarists. Their avarice for 
power , their desire to enrich their have-not nation, their hatred for white 
Occidental civilization, started them on a decade-long march of conquest. 
They withdrew from the League of Nations. They began beefing up the 
Army. They denounced the naval disarmament treaties and began an 
almost frantic ship-building race . Nor did they neglect, as part of their 
war-making capital, their cryptographic assets . In 1934, their Navy 
purchased a commercial German cipher machine called the Enigma ; that 
same year, the Foreign Office adopted it, and it evolved into the most 
secret Japanese system of cryptography. A variety of other cryptosystems 
supplemented it. The War, Navy, and Foreign ministries shared the 
superenciphered numerical HATO code for intercommunication. Each 
ministry also had its own hierarchy of codes. The Foreign Office, for 
example, employed four main systems, each for a specific level of 
security, as well as some additional miscellaneous ones . 
Meanwhile , the modern-style shoguns speared into defenseless China , 
sank the American gunboat Panay, raped Nanking, molested American 
hospitals and missions in China, and raged at American embargoes on 
oil and steel scrap. It became increasingly evident that Nippon's march of 
aggression would eventually collide with American rectitude. The 
mounting curve of tension was matched by the rising output of the 
American cryptanalytic agencies. A trickle of MAGIC in 1936 had become a 
stream in 1940. Credit for this belongs largely to Major General Joseph 
O. Mauborgne, who became Chief Signal Officer in October, 1937. 
Mauborgne had long been interested in cryptology. In 1914, as a 
young first lieutenant, he achieved the first recorded solution of a cipher 
known as the Playfair, then used by the British as their field cipher. He 
described his technique in a 19-page pamphlet that was the first 
publication on cryptology issued by the United States government. In 
World War I, he put together several cryptographic elements to create the 
only theoretically unbreakable cipher, and promoted the first automatic  
cipher machine, with which the unbreakable cipher was associated. 
When he became head of the Signal Corps, he immediately set about 
augmenting the important cryptanalytic activities. He established the 
S.I.S. as an independent division reporting directly to him, enlarged its 
functions, set up branches, started correspondence courses, added 
intercept facilities , increased its budget , and put on more men. In 1939, 
when war broke out in Europe , S.I.S. was the first agency in the War 
Department to receive more funds, personnel, and space. Perhaps most 
important of all, Mauborgne's intense interest inspired his men to 
outstanding accomplishments. More and more codes were broken , and 
as the international situation stimulated an increasing flow of intercepts, 
the MAGIC intelligence approached flood stage. 
Mauborgne retired in September, 1941, leaving an expanded  
organization running with smooth efficiency. By then the Japanese had 
completed the basic outline for a dawn attack on Pearl Harbor. The plan 
had been conceived in the fertile brain of Admiral Isoroku Yamamoto, 
Commander-in-Chief Combined Fleet , Imperial Japanese Navy. Early in 
the year, he had ordered a study of the operation, contending that "If we 
have war with the United States, we will have no hope of winning unless  
the United States fleet in Hawaiian waters can be destroyed." By May 
1941, studies had shown the feasibility of a surprise air attack, statistics 
had been gathered, and operational planning was under way. 
In the middle of that month , the U.S. Navy took an important step in 
the radio intelligence field. It detached a 43-year-old lieutenant 
commander from his intelligence berth aboard U.S.S. Indianapolis and 
assigned him to reorganize and strengthen the radio intelligence unit at 
Pearl Harbor. The officer was Joseph John Rochefort, the only man in the 
Navy with expertise in three closely related and urgently needed fields: 
cryptanalysis, radio, and the Japanese language. Rochefort, who had 
begun his career as an enlisted man, had headed the Navy's 
cryptographic section from 1925 to 1927. Two years later, a married man 
with a child , he was sent, because of his outstanding abilities, as a 
language student to Japan, a hard post to which ordinarily only bachelor 
officers were sent. This three-year tour was followed by half a year in 
naval intelligence; most of the next eight years were spent at sea. 
Finally , in June of 1941, Rochefort took over the command of what 
was then known as the Radio Unit of the 14th Naval District in Hawaii. 
To disguise its functions he renamed it the Combat Intelligence Unit. His 
mission was to find out, through communications intelligence, as much 
as possible about the dispositions and operations of the Japanese Navy. 
To this end he was to cryptanalyze all minor and one of the two major 
Japanese naval crypto -systems. 
His chief target was the flag officers' system, the Japanese Navy's 
most difficult and the one in which it encased its most secret 
information. From about 1926 to the end of November, 1940, previous 
editions had provided the U.S. Navy with much of its information on the 
Japanese Navy. But the new version—a four- character code with a 
transposition superencipherment—was stoutly resisting the best efforts 
of the Navy's most skilled cryptanalysts, and Rochefort was urged to 
concentrate on it. The other major system, the main fleet cryptographic 
system, the most widely used, comprised a code with five digit code-
numbers to which were added a key of other numbers to complicate the 
system. The Navy called it the "five numeral system," or, more formally, 
JN25b—the JN for "Japanese Navy," the 25 an identifying number, the b 
for the second (and current ) edition. Navy cryptanalytic units in 
Washington and the Philippines were working on this code. Rochefort's 
unit did not attack this but did attack the eight or ten lesser codes 
dealing with personnel, engineering , administration, weather , fleet 
exercises. 
But cryptanalysis was only part of the unit's task . The great  majority  
of its 100 officers and men worked on two other aspects of radio 
intelligence—direction-finding and traffic analysis. 
Direction-finding locates radio transmitters. Since radio signals are 
heard best when the receiver points at the transmitter, sensitive  
antennas can find the direction from which a signal is coming by 
swinging until they hear it at its loudest. If two direction- finders take 
bearings like that on a signal and a control center draws the lines of 
direction on a map, the point at which they cross marks the position of 
the transmitter. Such a fix can tell quite precisely where, for example, a 
ship is operating . Successive fixes can plot its course and speed . 
To exploit this source of information, the Navy in 1937 established the 
Mid-Pacific Strategic Direction-Finder Net. By 1941, high- frequency  
direction-finders curved in a gigantic arc from Cavite in the Philippines 
through Guam , Samoa, Midway, and Hawaii to Dutch Harbor, Alaska. 
The 60 or 70 officers and men who staffed these outposts reported their 
bearings to Hawaii, where Rochefort's unit translated them into fixes. For 
example, on October 16, the ship with call-sign KUNA 1 was located at 
10.7 degrees north latitude, 166.7 degrees east longitude—or within 
Japan's mandated islands . 
These findings did not serve merely to keep an eye on the day-to-day 
locations of Japanese warships. They also formed the basis of the even 
more fruitful technique of traffic analysis. Traffic analysis deduces the 
lines of command of military or naval forces by ascertaining which radios 
talk to which. And since military operations are usually accompanied by 
an increase in communications, traffic analysis can infer the imminence 
of such operations by watching the volume of traffic. When combined 
with direction-finding, it can often approximate the where and when of a 
planned movement . 
Radio intelligence thus maintains a long-range, invisible, and 
continuous surveillance of fleet movements and organization, providing a 
wealth of information at a low cost . Of course it has its limitations. A 
change of the call-signs of radio transmitters can hinder it. The sending 
of fictitious messages can befuddle it. Radio silences can deafen it. But it 
cannot be wholly prevented except by unacceptable restrictions on 
communications. Hence the Navy relied increasingly on it for its 
information on Japanese naval activities as security tightened in Japan 
during 1941, and almost exclusively after July , when the President's 
trade-freezing order deprived the Navy of all visual observations of 
Japanese ships not on the China coast. 
It was in July that a Japanese tactic set up a radio pattern that was 
later to deceive the Combat Intelligence Unit. The Nipponese militarists 
had decided to take advantage of France 's defeat and occupy French  
Indochina. The Naval preparations for the successful grab were clearly  
indicated in the radio traffic, which went through the usual three stages 
that preceded major Japanese operations. First appeared a heavy flurry 
of messages. The Commander-in-Chief Combined Fleet busily originated 
traffic, talking with many commands to the south , thereby indicating the 
probable direction of his advance. Then came a realignment of forces. In 
the lingo of the tranalysis people, certain chickens (fleet units) no longer 
had their old mothers (fleet commanders). Call-sign NOTA 4, which 
usually communicated with OYO 8, now talked mostly with ORU 6. 
Accompanying this was a considerable confusion in the routing of 
messages, with frequent retransmissions caused by the regrouping: 
Admiral z not here; try Second Fleet. Then followed the third phase: radio 
silence. The task force was now under way. Messages would be 
addressed to it, but none would emanate from it. 
During all this, however, not only were no messages heard from the 
aircraft carriers, none were sent to them, either. This blank condition  
exceeded radio silence, which suppresses traffic in only one direction—
from the mobile force—not in both. American intelligence reasoned that 
the carriers were standing by in home waters as a covering force in case 
of counterattack, and that communications both to and from them were 
not heard because they were being sent out by short-range, low-powered 
transmissions that died away before reaching American receivers. Such a 
blank condition had obtained in a similar tactical situation in February. 
American intelligence had drawn the same conclusions then and had 
been proven right. Events soon confirmed the July assessment as well. 
Twice, then, a complete blank of carrier communications combined with 
indications of a strong southward thrust had meant the presence of the 
carriers in Empire waters. But what happened in February and July was 
not necessarily what would happen in December. 
 
During the summer and fall of 1941, the pressure of events molded 
America's two cryptanalytic agencies closer and closer to the form they 
were to have on December 7. The Signal Intelligence Service, which had 
181 officers, enlisted men, and civilians in Washington and 150 at 
intercept stations in the field on Pearl Harbor Day, had been headed 
since March by Lieutenant Colonel Rex W. Minckler, a career Signal 
Corps officer. Friedman served as his chief technical assistant. S.I.S. 
comprised the Signal Intelligence School, which trained Regular Army 
and Reserve officers in cryptology, the 2nd Signal Service Company, 
which staffed the intercept posts, and four Washington sections of the 
S.I.S. proper: the A, or administrative, which also operated the tabulating 
machinery; the B, or cryptanalytic; the c, or cryptographic, which 
prepared new U.S. Army systems, studied the current systems for 
security, and monitored Army traffic for security violations; and the D, or 
laboratory , which concocted secret inks and tested suspected 
documents . 
The B section, under Major Harold S. Doud, a West Point graduate , 
had as its mission the solution of the military and diplomatic systems 
not only of Japan but of other countries. In this it apparently achieved at 
least a fair success , though no Japanese military systems—the chief of 
which was a code employing four-digit codenum-bers—were readable by 
December 7 because of a paucity of material. Doud's technical assistant 
was a civilian, Frank B. Rowlett, one of the three original junior 
cryptanalysts hired in 1930. The military man in charge of Japanese 
diplomatic solutions was Major Eric Svensson. 
The Navy's official designation of OP-20-G indicated that the agency 
was the G section of the 20th division of OPNAV, the Office of the Chief of 
Naval Operations, the Navy's headquarters establishment . The 20th 
division was the Office of Naval Communications, and the G section was 
the Communication Security Section. This carefully chosen name 
masked its cryptanalytic activities, though its duties did include U. S. 
Navy cryptography. 
Its chief was Commander Laurence F. Safford, 48, a tall , blond  
Annapolis graduate who was the Navy's chief expert in cryptology. In 
January , 1924, he had become the officer in charge of the newly created 
research desk in the Navy's Code and Signal Section. Here he founded  
the Navy's communication-intelligence organization. After sea duty from 
1926 to 1929, he returned to cryptologic activities for three more years, 
when sea duty was again made necessary by the "Manchu" laws , which 
required officers of the Army and Navy to serve in the field or at sea to 
win promotion . He took command of OP-20-G in 1936. One of his 
principal accomplishments before the outbreak of war was the 
establishment of the Mid-Pacific Strategic Direction-Finder Net and of a 
similar net for the Atlantic , where it was to play a role of immense 
importance in the Battle of the Atlantic against the U-boats. 
Safford's organization enjoyed broad cryptologic functions. It printed 
new editions of codes and ciphers and distributed them, and contracted 
with manufacturers for cipher machines. It developed new systems for 
the Navy. It comprehended such subsections as GI, which wrote reports 
based on radio intelligence from the field units, and GL, a record-keeping 
and historical-research group. But its main interest centered on 
cryptanalysis. 
This activity was distributed among units in Washington, Hawaii, and 
the Philippines. Only Washington attacked foreign diplomatic systems 
and naval codes used in the Atlantic theater (primarily German). 
Rochefort had primary responsibility for the Japanese naval systems. 
The Philippines chipped away at JN25 and did some diplomatic 
deciphering, with keys provided by Washington. That unit, which like 
Rochefort's was attached for administrative purposes to the local naval 
district (the 16th ), was installed in a tunnel of the island fortress of 
Corregidor. It was equipped with 26 radio receivers, apparatus for 
intercepting both high- and low-speed transmissions, a directionfinder, 
and tabulating machinery. Lieutenant Rudolph J. Fabian , 33, an 
Annapolis graduate who had had three years of radio intelligence 
experience in Washington and the Philippines, commanded. The 7 
officers and 19 men in his cryptanalytic group exchanged possible 
recoveries of JN25b codegroups with Washington and with a British 
group in Singapore; each group also had a liaison man with the other. 
Of the Navy's total radio-intelligence establishment of about 700 
officers and men, two thirds were engaged in intercept or direction-
finding activities and one third— including most of the 80 officers—in 
cryptanalysis and translation. Safford sized up the personnel of his three 
units this way: Pearl Harbor had some of the best officers, most of whom  
had four or five years of radio intelligence experience; the crew at 
Corregidor, which in general had only two or three years' experience, was 
"young, enthusiastic, and capable"; Washington—responsible for both 
overall supervision and training—had some of the most experienced  
personnel, with more than ten years' experience, and many of the least: 
90 per cent of the unit had less than a year's experience. 
Under Safford in the three subsections most closely involved with 
cryptanalysis were Lieutenant Commanders George W. Welker of GX, the 
intercept and direction-finding subsection, Lee W. Parke of GY, the 
cryptanalytical subsection, and Kramer of GZ, the translation and 
dissemination subsection. GY attacked new systems and recovered new 
keys for solved systems, such as PURPLE. But while it made the initial 
breaks in code solutions, the detailed recovery of codegroups (which was 
primarily a linguistic problem as compared to the more mathematical 
cipher solutions) was left to GZ. Four officers in GY,  assisted by chief petty  
officers, stood round -the-clock watches. Senior watch officer was 
Lieutenant (j.g.) George W. Lynn ; the others were Lieutenants (j.g.) 
Brotherhood, Pering, and Allan A. Murray . GY had others on its staff , 
such as girl typists who also did the simple deciphering of some 
diplomatic messages after the watch officers and other cryptanalysts had 
found the keys. 
Kramer was in an odd position. Though he worked in OP-20-GZ, he 
was formally attached to OP-16-F2—the Far Eastern Section of the Office 
of Naval Intelligence. This arrangement was intended in part to throw off 
the Japanese, who might have inferred some measure of success in 
codebreaking if a Japanese-language officer like Kramer were assigned to 
communications, in part to have an officer with a broad intelligence 
background distribute MAGIC so that he could answer the recipients' 
questions. Kramer, 38, who had studied in Japan from 1931 to 1934, 
had had two tours in O.N.I, proper before being assigned full time to GZ 
in June, 1940. An Annapolis graduate, chess fan, and rifle marksman, 
he lived in a world in which everything had one right way to be done. He 
chose his words with almost finicky exactness (one of his favorites was 
"precise"); he kept his pencil mustache trimmed to a hair ; he filed his 
papers tidily; he often studied his MAGIC intercepts several times over 
before delivering them. Included in this philosophy was his duty. He 
performed it with great responsibility, intelligence, and dedication . 
 
The first task of OP-20-G and of S.I.S. was to obtain intercepts. And in 
peacetime America that was not easy . 
Section 605 of the Federal Communications Act of 1934, which 
prohibits wiretaps, also prohibits the interception of messages between 
foreign countries and the United States and territories. General Malin 
Craig , Chief of Staff from 1937 to 1939, was acutely aware of this, and 
his attitude dampened efforts to intercept the Japanese diplomatic 
messages coming into America. But after General George C. Marshall 
succeeded to Craig's post, the exigencies of national defense relegated 
that problem in his mind to the status of a legalistic quibble. The crypt-
analytic agencies pressed ahead in their intercept programs. The extreme  
secrecy in which they were cloaked helped them avoid detection. They 
concentrated on radio messages, since the cable companies , fully 
cognizant of the legal restrictions, in general refused to turn over any 
foreign communications to them. Consequently, 95 per cent of the 
intercepts were radio messages. The remainder was split between cable 
intercepts and photographs of messages on file at a few cooperative cable 
offices. 
To pluck the messages from the airwaves, the Navy relied mainly on 
its listening posts at Bainbridge Island in Puget Sound; Winter Harbor, 
Maine; Cheltenham, Maryland; Heeia, Oahu ; and Corregidor and to a 
lesser degree on stations at Guam; Imperial Beach , California ; 
Amagansett, Long Island and Jupiter , Florida . Each station was assigned 
certain frequencies to cover. Bainbridge Island, which was called Station 
S, copied solid the schedule of Japanese government messages between 
Tokyo and San Francisco . Its two sound recorders guarded the 
radiotelephone band of that circuit; presumably it was equipped to 
unscramble the relatively simple sound inversion that then provided 
privacy from casual eavesdropping. Diplomatic messages were 
transmitted almost exclusively by commercial radio using roman letters. 
The naval radiograms, however, employed the special Morse code devised 
for kata kana , a syllabic script of Japanese. The Navy picked these up 
with operators trained in Japanese Morse and recorded them on a 
special typewriter that it had developed for the roman-letter equivalents 
of the kana characters . The Army's stations, called Monitor Posts, were: 
No. 1, Fort Hancock , New Jersey ; No. 2, San Francisco; No. 3, Fort Sam 
Houston, San Antonio ; No. 4, Panama; No. 5, Fort Shafter, Honolulu; No. 
6, Fort Mills , Manila ; No. 7, Fort Hunt, Virginia ; No. 9, Rio de Janeiro . 
At first both services airmailed messages from their intercept posts to 
Washington. But this proved too slow . The Pan-American Clipper, which 
carried Army intercepts from Hawaii to the mainland, departed only once 
a week on the average , and weather sometimes caused cancellations, 
forcing messages to be sent by ship. As late as the week before Pearl 
Harbor, two Army intercepts from Rio did not reach Washington for 
eleven days . Such delays compelled the Navy to install teletypewriter 
service in 1941 between Washington and its intercept stations in the 
continental U.S. The station would perforate a batch of intercepts onto a 
teleptype tape, connect with Washington through a teletypewriter 
exchange, and run the tape through mechanically at 60 words per 
minute, cutting toll charges to one third the cost of manually sending 
each message individually. Outlying stations of both the Army and Navy 
picked out Japanese messages bearing certain indicators, enciphered the 
Japanese cryptograms in an American system, and radioed them to 
Washington. The reencipherment was to keep the Japanese from 
knowing of the extensive American cryptanalytic effort. Only the three 
top Japanese systems were involved in this expensive radio 
retransmission: PURPLE, RED (a machine system that antedated PURPLE, 
which had supplanted it at major embassies, but that was still in use for 
legations such as Vladivostok), and the J series of enciphered codes. The 
Army did not install a teletype for intercepts from its continental posts 
until the afternoon of December 6, 1941; the first messages (from San 
Francisco) were received in the early morning hours of December 7. 
The intercept services missed little. Of the 227 messages pertaining to 
Japanese-American negotiations sent between Tokyo and Washington 
from March to December, 1941, all but four were picked up. 
In Honolulu, where a large Japanese population produced nightmares 
of antlike espionage and potential sabotage, the 14th Naval District's 
intelligence officer, Captain Irving S. Mayfield, had long sought to obtain 
copies of the cablegrams of Consul General Nagao Kita . If Rochefort's 
unit could solve these, Mayfield figured, he might know better which 
Japanese to shadow and what information they sought. 
His intuitions were sound. On March 27, 1941, not two weeks after 
Mayfield himself took up his duties, a young ensign of the Imperial 
Japanese Navy, 25-year-old Takeo Yoshikawa, who had steeped himself 
in information about the American Navy, arrived in Honolulu to serve as 
Japan's only military espionage agent covering Pearl Harbor. Under the 
cover-name "Tadasi Morimura," he was assigned to the consulate as a 
secretary. He promptly made himself obnoxious—and drew suspicion 
upon himself within the consulate staff—by coming to work late or not at 
all, getting drunk frequently, having women in his quarters overnight, 
and even insulting the consul himself on occasion. But he managed to 
tour the islands, and within a month was sending such messages as: 
"Warships observed at anchor on the llth [of May, 1941] in Pearl Harbor 
were as follows: Battleships , 11: Colorado, West Virginia, California, 
Tennessee . . . ."  These were sent in the consulate's diplomatic systems, 
not in naval code. 
But Mayfield's hopes of peering into these secret activities through the 
window of a broken code were stymied by the refusal of the cable offices 
to violate the statute against interception. So when David Sarnoff, 
president of the Radio Corporation of America, vacationed in Hawaii, 
Mayfield spoke to him. It was subsequently arranged that thenceforth 
R.C.A.'s Japanese consulate messages would be quietly given to the 
naval authorities. But the consulate rotated its business among the 
several cable companies in Honolulu, and R.C.A.'s turn was not due until 
December 1. 
 
In Washington, however, intercepts overwhelmed GY and S.I.S. The 
tiny staff of cryptanalysts simply could not cope with all of them 
expeditiously. This difficulty was resolved in two ways. 
One was to cut out duplication of effort. At first, both services solved 
all their Japanese diplomatic intercepts. But beginning more than a year 
before Pearl Harbor, messages originating in Tokyo on odd-numbered 
days of the month were handled by the Navy, those on even days, by the 
Army. Each began breaking the messages sent in from its own intercept 
stations until it reached the Tokyo date of origin; it would then retain 
them or send them over as the dates indicated. The cryptanalysts utilized 
the extra time to attack as-yet-unbroken systems and to clean up 
backlogs. 
The other method was to concentrate on the important intercepts and 
let the others slide, at least until the important ones were completed. But 
how can a cryptanalyst tell which messages are important until he has 
solved them? He cannot, but he can assume that messages sent in the 
more secret systems are the more important. All dispatches cannot be 
transmitted in a single system because the huge volume of traffic would 
enable cryptanalysts to break it too quickly. Hence most nations set up a 
hierarchy of systems, reserving the top ones for their vital needs. 
Japan was no exception. Though her Foreign Office employed an 
almost bewildering variety of different codes, resorting, from time to time, 
to the Yokohama Specie Bank 's private code, a Chinese ideographic code 
list, and codes bearing kata kana names, such as TA, JI, or HEN, it relied 
in the main on four systems. American cryptanalysts ranked these on 
four levels according to the inherent difficulty of their solution and the 
messages that they generally carried. Intercepts were then solved in the 
order of this priority schedule. 
Simplest of all, and hence the lowest in rank and last to be read 
(excluding plain language), was the LA code, so called from the indicator  
group LA that preceded its codetexts. LA did little more than put kata 
kana into roman letters for telegraphic transmission and to secure some 
abbreviation for cable economy. Thus the kana for ki was replaced by the 
code form CI, the kana for to by IF, the two-kana combination of ka + n by 
CE. Its two-letter codewords, all of either vowel - consonant or consonant-
vowel form and including such as ZO for 4, were supplemented by a list 
of four-letter codewords, such as TUVE for dollars, SISA for ryoji ("consul"), 
and XYGY for Yokohama. A very typical  LA message is serial 01250 from 
the Foreign Minister to Kita, dated December 4, which begins in 
translation: "The following has been authorized as the year-end bonus for 
employee typists of your office." This sort of code is generally called a 
"passport code" because it usually serves for messages covering the 
administrative routine of a mission, such as issuance of passports and 
visas. LA was a particularly simple one to solve, partly because it had 
been in effect since 1925, partly because of the regularities in its 
construction . For example, all kana that ended in e had as code 
equivalents groups beginning with A (ke = AC, se = AD), and all that began 
with k had code equivalents beginning or ending with C. Identification of 
one kana would thus suggest the identification of others. 
One rung up the cryptographic ladder was the system known to the 
Japanese as Oite and to American code-breakers as PA-K2. The PA part 
was a two- and four-letter code similar to the LA, though much more 
extensive and with codegroups disarranged. The K2 part was a 
transposition based on a keynumber. The letters from the PA encoding 
were written under this keynumber from right to left and then copied out 
in mixed order, taking first the letter under number 1, then the letter 
under number 2, until the row was completed. The process was repeated 
for successive rows. 
For example, on December 4 Yoshikawa wired the Foreign Minister 
that "At 1 o'clock on the 4th a light cruiser of the Honolulu  class hastily 
departed—Morimura." In romaji (the roman-letter version of the kata 
kana) this became 4th gogo 1 kei jun (honoruru) kata hyaku shutsu ko—
morimura. In PA, with the parentheses getting their own codegroups (OQ 
and UQ), it assumed this form: BYDH DOST JE YO IA OQ GU RA HY HY UQ VI LA YJ 
AY EC TY FI BANL, with FI indicating use four-letter code. (The code clerk  
made two errors. After encoding kata by VI, he encoded an extra ta into 
LA and an unnecessary re into TY.) This was then written under the 
keynumber from right to left, with an extra letter I as a null to complete 
the final five-letter group: 
 
10 15 11 16 2 8 1 5 17 3 7 13 19 4 18 6 12 9 14
 B  Y  D  H D  O S T  J E Y O  I A  O Q  G U  R 
 A  H  Y  H Y  U Q V  I L A Y  J A  Y E  G T  Y 
            F    I B    A N      L    I 
Transcribed line by line according to the numbers (s under 1 first, D 
under 2 second, etc.), prefixed with system indicator  GIGIG  and key 
indicator AUDOB, the message number, and the telegraphic abbreviation 
of Sikuyu ("urgent"), the message (with three more errors: the Y under 13 
became the J in CJYHH, the F under 2 became the E in IYJIE, and the T 
under 9 became the i in AUIAY) became the one actually sent over Kita's 
name: 
 
GAIMUDAIJIN TOKIO  
SIKYU 02500 GIGIG AUDOB SDEAT QYOUB DGORY HJOIQ YLAVE 
AUIAY CJYHH IYJIE ALBIN 
KITA 
 
PA-K2 did not pose much of a problem to experienced American 
cryptanalysts. ROchefort estimated that his unit could crack a PA-K2 
message in from six hours to six days, with three days a good average. 
The transposition was vulnerable because each line was shuffled 
identically; the cryptanalyst could slice a cryptogram into groups of 15 or 
17 or 19 and anagram these simultaneously until the predominant 
vowel-consonant alternation appeared on all lines; the underlying code 
could then be solved by assuming that the most frequent codegroups 
represented the most frequent kana (i, followed by ma, shi, o, etc.) and 
filling out the skeleton words that resulted. Since the system had 
remained in use for several years, this reconstruction had long been 
accomplished by the Washington agencies. Hence solution involved only 
unraveling any new transposition and, with luck , might take only a few 
hours. It could also take a few days. Primarily because of PA-K2's 
deferred position in the priority list, an average of two to four days 
elapsed between interception and translation. 
The code clerk in Honolulu enveloped Yoshikawa's final messages in 
PA-K2 only because higher -level codes had been destroyed December 2 
on orders from Tokyo. Normally, espionage reports of shipping 
movements and military activities, sent routinely by Japanese consuls 
from their posts all over the world, were framed on that next level of 
secrecy. Here prevailed a succession of codes called TSU by the Japanese 
and the J series by Americans. These were even more extensive and more 
thoroughly disarranged than PA, and they were transposed by a system of 
far greater complexity than the rather simple and vulnerable K2. 
Furthermore, the code and the transposition were changed at frequent 
intervals. Thus J17-K6 was replaced on March 1 by J18-K8, and that in 
turn by J19-K9 on August 1. 
The transposition was the real stumbling block. Like the K2, it used a 
keynumber, but it differed in being copied off vertically instead of 
horizontally, and in having a pattern of holes in the transposition blocks. 
These holes were left blank when the code groups are inscribed into the 
block. For example, letting the alphabet from A to Y serve as the code 
message: 
 
[CodeBreakers 020.jpg]
 
The letters were transcribed in columns in the order of the 
keynumbers, skipping over the blanks: BJMV EHKT NW CGORX AFILQU DPSY. 
This would be sent in the usual five-letter groups. 
The first step in solving a columnar transposition like this, but 
without blanks, is to cut the cryptogram into the approximately equal 
segments that the cryptanalyst believes represent the columns of the 
original block. The blanks vastly increase the difficulty of this essential  
first step because they vary the length of the column segments. The 
second step is to reconstruct the block by trying one segment next to the 
other until a codeword-like pattern appears . Here again the blanks, by 
introducing gaps in unknown places between the letters of the segments, 
greatly hinder the cryptanalyst. 
The problems of solving such a system are illustrated by the fact that 
J18-K8 was not broken until more than a month after its introduction . 
The cryptanalysts had to make a fresh analysis for each pattern of 
blanks and each transposition key. The key changed daily, the blank-
pattern three times a month. Hence J19-K9 solutions were frequently 
delayed. The key and pattern for November 18 were not recovered until 
December 3; those for November 28, not until December 7. On the other 
hand, solution was sometimes effected within a day or two. Success 
usually depended on the quantity of intercepts in a given key. About 10 
or 15 per cent of J19-K9 keys were never solved. 
This situation contrasts with that of PURPLE, the most secret Japanese 
system, in which all but 2 or 3 per cent of keys were recovered and in 
which most messages were solved within hours. Did the Japanese err in 
assessing the security of their systems? Yes and no. PURPLE was easier to 
keep up with once it was solved, but it was a much more difficult system 
to break in the first place than J19-K9. The solution of the PURPLE 
machine was, in fact, the greatest feat of cryptanalysis the world had yet 
known. 
 
The cipher machine that Americans knew as PURPLE bore the 
resounding official Japanese title of 97-shiki O-bun In-ji-ki. This meant 
Alphabetical Typewriter '97, the '97 an abbreviation for the year 2597 of 
the Japanese calendar , which corresponds to 1937. The Japanese 
usually referred to it simply as "the machine" or as "J,"1 the name given 
it by the Imperial Japanese Navy, which had adapted it from the German 
Enigma cipher machine and then had lent it to the Foreign Ministry, 
which, in turn, had further modified it. Its operating parts were housed 
in a drawer -sized box between two big black electrically operated 
Underwood typewriters, which were connected to it by 26 wires plugged 
into a row of sockets called a plugboard. To encipher a message, the 
cipher clerk would consult the thick YU GO book of machine keys, plug in 
the wire connections according to the key for the day, turn the four disks 
in the box so the numbers on their edges were those directed by the YU 
GO, and type out the plaintext. His machine would record that plaintext 
while the other, getting the electric impulses after the coding box had 
twisted them through devious paths, would print out the cipher-text. 
Deciphering was the same, though the machine irritatingly printed the 
plaintext in the five-letter groups of the ciphertext input. 
The Alphabetical Typewriter worked on roman letters, not kata kana. 
Hence it could encipher English as well as romaji—and also roman-letter 
codetexts, like those of the J codes. Since the machine could not 
encipher numerals or punctuation, the code clerk first transformed them 
into three-letter codewords, given in a small code list, and enciphered 
these. The receiving clerk would restore the punctuation, paragraphing, 
and so on, when typing up a finished copy of the decode. 
The coding wheels and plugboards produced a cipher of great 
difficulty. The more a cipher deviates from the simple form in which one 
ciphertext letter invariably replaces the same plaintext letter, the harder 
it is to break. A cipher might replace a given plaintext letter by five 
different ciphertext letters in rotation, for example. But the Alphabetical 
Typewriter produced a substitution series hundreds of thousands of 
letters long. Its coding wheels, stepping a space—or two, or three, or 
four—after every letter or so, did not return to their original positions to 
re-create the same series of paths, and hence the same sequence of 
substitutes, until hundreds of thousands of letters had been enciphered. 
The task of the cryptanalysts consisted primarily of reconstructing the 
wiring and switches of the coding wheels—a task made more 
burdensome by the daily change of plugboard connections. Once this 
was done, the cryptanalyst still had to determine the starting position at 
the coding wheels for each day's messages. But this was a comparatively 
simple secondary job. 
American cryptanalysts knew none of these details when the 
Japanese Foreign Office installed the Alphabetical Typewriter in its major 
embassies in the late 1930s . How, then, did they solve it? Where did they 
begin ? How did they even know that a new machine was in service, since 
the Japanese government did not announce it? 
The PURPLE machine supplanted the RED machine,2 which American 
cryptanalysts had solved, and so probably their first clue to the new 
machine was the disconcerting discovery that they could no longer read 
the important Japanese messages. At the same time, they observed new 
indicators for the PURPLE system. Clues to the system's nature came from 
such characteristics of its ciphertext as the frequency of letters, the 
percentage of blanks (letters that did not appear in a given message), and 
the nature and number of repetitions. Perhaps the codebreakers also 
assumed that the new machine comprised essentially a more 
complicated and improved version of the one it replaced. In this they 
were right. 
Their first essays at breaking into the cipher both accompanied and 
supplemented their attempts to determine the type of cipher. Their 
previous success with the RED machine and with the lesser systems had 
given them insight into the Japanese diplomatic forms of address, 
favorite phrases, and style (paragraphs were often numbered, for 
example). These provided the cryptanalysts with probable words—words 
likely to be in the plaintext— that would help in breaking the cipher. 
Opening and closing formulas , such as "I have the honor to inform Your 
Excellency" and "Re your telegram," constituted virtual cribs. Newspaper  
stories suggested the subject matter of intercepts. The State Department 
sometimes made public the full texts of diplomatic notes from Japan to 
the American government, in effect handing the cryptanalysts the 
plaintext (or its translation) of an entire dispatch. (State reportedly did 
not pass the texts of confidential notes to the cryptanalysts, though this 
would have helped them considerably and was done by other foreign 
ministries.) Japan's Foreign Office often had to circulate the same text to 
several embassies, not all of which had a PURPLE machine, and a code 
clerk might have inadvertently encoded some cables in PURPLE, some in 
other systems— which the cryptanalysts could read. A comparison of 
times of dispatch and length, and voilá!—another crib to a cryptogram. 
Errors were, as always, a fruitful source of clues. As late as November, 
1941, the Manila legation repeated a telegram "because of a mistake on 
the plugboard." How much more common must errors have been when 
the code clerks were just learning to handle the machine! The sending of 
the identical text in two different keys produces "isomorphic" 
cryptograms that yield exceedingly valuable information on the 
composition of the cipher. 
The cryptanalysts of S.I.S. and OP-20-G, then, matched these 
assumed plaintexts to their ciphertexts and looked for regularities from 
which they could derive a pattern of encipherment. This kind of work, 
particularly in the early stages of a difficult cryptanalysis, is perhaps the 
most excruciating, exasperating, agonizing mental process known to 
man. Hour after hour, day after day, sometimes month after month, the 
cryptanalyst tortures his brain to find some relationship between the 
letters that hangs together, does not dead-end in self-contradiction, and 
leads to additional valid results . 
The codebreakers attacking the new Japanese mechanism went just 
so far—and for months could not push on further. As William Friedman 
recalled, "When the PURPLE system was first introduced it presented an 
extremely difficult problem on which the Chief Signal Officer [Mauborgne] 
asked us to direct our best efforts. After work by my associates when we 
were making very slow progress, the Chief Signal Officer asked me 
personally to take a hand. I had been engaged largely in administrative 
duties up to that time, so at his request I dropped everything else that I 
could and began to work with the group." 
Lighting his way with some of the methods that he himself had 
developed, he led the cryptanalysts through the murky PURPLE 
shadowland. He assigned teams to test various hypotheses. Some 
prospected fruitlessly, their only result a demonstration that success lay 
in another direction. Others found bits and pieces that seemed to make 
sense. (OP-20-G cooperated in this work, with Harry L. Clark making 
especially valuable contributions, but S.I.S. did most of it.) Friedman and 
the other codebreakers began to segregate the ciphertext letters into 
cycles representing the rotation of the coding wheels—gingerly at first, 
then faster and faster as the evidence accumulated. The polyalphabetic 
class of ciphers, to which PURPLE belonged, is based ultimately upon an 
alphabet table, usually 26 letters by 26. To reconstruct the PURPLE tables, 
the cryptanalysts employed both direct and indirect symmetry of 
position— names only slightly less forbidden than the methods they 
denote. Errors, caused perhaps by garbled interceptions or simple 
mistakes in the cryptanalysis, jarred these delicate analyses and delayed 
the work. But slowly it progressed. A cryptanalyst, brooding sphinxlike 
over the cross-ruled paper on his desk, would glimpse the skeleton of a 
pattern in a few scattered letters; he tried fitting a fragment from another 
recovery into it; he tested the new values that resulted and found that 
they produced acceptable plaintext; he incorporated his essay into the 
over-all solution and pressed on. Experts in Japanese filled in missing 
letters; mathematicians tied in one cycle with another and both to the 
tables. Every weapon of cryptanalytic science—which in the stratospheric 
realm of this solution drew heavily upon mathematics, using group 
theory, congruences, Poisson distributions—was thrown into the fray. 
Eventually the solution reached the point where the cryptanalysts had 
a pretty good pencil-and-paper analog of the PURPLE machine. S.I.S. then 
constructed a mechanism that would do automatically what the 
cryptanalysts could do manually with their tables and cycles. They 
assembled it out of ordinary hardware and easily available pieces of 
communication equipment , such as the selector switches used for 
telephones. It was hardly a beautiful piece of machinery, and when not 
running just right it spewed sparks and made loud whirring noises. 
Though the Americans never saw the 97-shiki O-bun In-ji-ki, their 
contraption bore a surprising physical resemblance to it, and of course 
exactly duplicated it cryptographically. 
S.I.S. handed in its first complete PURPLE solution in August of 1940, 
after 18 or 20 months of the most intensive analysis. In looking back on 
the effort that culminated in this, the outstanding cryptanalytic success 
in the whole history of secret writing up to its time, Friedman would say 
generously: 
 
Naturally this was a collaborative, cooperative effort on the part 
of all the people concerned. No one person is responsible for the 
solution, nor is there any single person to whom the major share of 
credit should go. As I say, it was a team, and it was only by very 
closely coordinated teamwork that we were able to solve it, which 
we did. It represents an achievement of the Army cryptanalytic 
bureau that, so far as I know, has not been duplicated elsewhere, 
because we definitely know that the British cryptanalytic service 
and the German cryptanalytic service were baffled in their 
attempts and they never did solve it. 
 
Friedman, was, despite his partial disclaimer, the captain of that 
team. The solution had taken a terrific toll. The restless turning of the 
mind tormented by a puzzle , the preoccupation at meals, the insomnia , 
the sudden wakening at midnight, the pressure to succeed because 
failure could have national consequences , the despair of the long weeks 
when the problem seemed insoluble, the repeated dashings of uplifted 
hopes, the mental shocks, the tension and the frustration and the 
urgency and the secrecy all converged and hammered furiously upon his 
skull . He collapsed in December. After three and a half months in Walter 
Reed General Hospital recovering from the nervous breakdown, he 
returned to S.I.S. on shortened hours, working at first in the more 
relaxed area of cryptosecurity. By the time of Pearl Harbor he was again 
able to do some cryptanalysis, this time of German systems. 
OP-20-G contributed importantly to the ease and speed of daily PURPLE 
solutions when 27-year-old Lieutenant (j.g.) Francis A. Raven discovered  
the key to the keys. After a number of PURPLE messages has been solved, 
Raven observed that the daily keys within each of the three ten-day 
periods of a month appeared to be related. He soon found that the 
Japanese simply shuffled the first day's key to form the keys for the next 
nine days, and that the nine shuffling patterns were the same in all the 
ten-day periods. Raven's discovery enabled the cryptanalysts to predict  
the keys for nine out of ten days. The cryptanalysts still had to solve for 
the first day's key by straightforward analysis, but this task and its 
delays were eliminated for the rest of the period. Furthermore, knowledge  
of the shuffles enabled the codebreakers to read all the traffic of a period 
even though they could solve only one of the daily keys. 
This fine piece of work, on the shoulders of the tremendous initial 
Friedman-S.I.S. effort, resulted in the paradoxical situation of Americans 
reading the most difficult Japanese diplomatic system more quickly and 
easily than some lower- grade systems. They also became very facile in 
reading two-step systems in which PURPLE superenciphered an already  
coded message. The Japanese did this from time to time to provide extra 
security, usually with the CA code, the personal code of an ambassador or 
head of mission. A year after S.I.S. handed in its first PURPLE solution, the 
cryptanalysts solved a message enciphered in "the highest type of secret 
classification used by the Japanese Foreign Office." The message was 
first enciphered in CA; this was then juggled according to the K9 
transposition (normally used with the J19 code), and the transposed 
codetext was then enciphered on the PURPLE machine. The solution, 
which on the basis of the number of combinations involved might have 
been expected to take geologic eons, was completed in just four days. 
 
The intercepts ordinarily needed to be translated, and translation was 
the bottleneck of the MAGIC production line. Interpreters of Japanese were 
even scarcer than expert cryptanalysts. Security precluded employing 
Nisei or any but the most trustworthy Americans. Through prodigious 
efforts in 1941 the Navy doubled its GZ translation staff —to six. These 
included three whom Kramer called "the most highly skilled Occidentals 
in the Japanese language in the world." 
But ability in standard Japanese alone did not suffice. Each 
translator had to have at least a year's experience in telegraphic 
Japanese as well before he could be trusted to come through with the 
correct interpretation of a dispatch. This is because telegraphic Japanese 
is virtually a language within a language, and, as McCollum, himself a 
Japanese-language officer, explained, "the so-called translator in this 
type of stuff almost has to be a cryptographer himself. You understand  
that these things come out in the form of syllables, and it is how you 
group your syllables that you make your words. There is no punctuation. 
"Now, without the Chinese ideograph to read from, it is most difficult 
to group these things together. That is, any two sounds grouped together 
to make a word may mean a variety of things. For instance , 'ba' may 
mean horses or fields, old women, or my hand, all depending on the 
ideographs with which it is written. On the so-called translator is forced 
the job of taking unrelated syllables and grouping them into what looks  
to him to be intelligible words, substituting then such of the Chinese 
ideographs necessary to pin it down, and then going ahead with the 
translation, which is a much more difficult job than simple translation." 
Hence the situation of Mrs. Dorothy Edgers. She had lived for thirty  
years in Japan and had a diploma from a Japanese school to teach  
Japanese to Japanese students up to high-school level. Yet, because she 
had only two weeks' experience in GZ at the time of Pearl Harbor, Kramer 
considered her "not a reliable translator" in this field. And on the 
important messages, only reliable translators could be used. To unclog 
this bottleneck, messages in the minor systems were given only a partial 
translation. If a translator saw that they dealt with administrative trivia, 
they were frequently not formally translated at all. 
With manifold streamlinings like that, with enlarged staffs, with the 
fluidity gained by experience, OP-20-G and S.I.S. gradually increased the 
speed and quality of their output. In 1939, the agencies had often 
required three weeks to funnel a message from interceptor to recipient . 
In the latter part of 1941 the process sometimes took as little as four 
hours. Occasionally an agency broke down a late intercept that bore on a 
point of Japanese-American negotiations and rushed it to the Secretary 
of State an hour before he was to meet with the Japanese ambassadors. 
Volume attained overwhelming proportions. By the fall of 1941, 50 to 75 
messages a day sluiced out of the two agencies, and at least once the 
quantity swelled to 130. Some of these messages ran to 15 typewritten 
pages. 
The top-echelon recipients of MAGIC clearly could not afford the time to 
read all this traffic. Much of it was of secondary importance anyway. 
Kramer and Colonel Rufus S. Bratton, army G-2 Far Eastern Section 
chief, winnowed the wheat from this chaff. Reading the entire output, 
they chose an average of 25 messages a day for distribution. At first 
Kramer supplemented his translations with gists for recipients too busy  
to read every word of the actual intercepts, starring the important ones, 
but he abandoned these in mid-November under the pressure of getting 
out the basic material. Bratton, who had been delivering summaries of 
MAGIC in the form of Intelligence Bulletins, began on August 5 to 
distribute MAGIC verbatim at Marshall's orders. This, however, had the 
effect of increasing the volume. Marshall complained that to absorb every 
word of it he would have had to "retire as Chief of Staff and read every 
day." To save the recipients' time, Bratton checked the important 
messages on a list in the folder with a red pencil; Kramer slid paper clips 
onto them. The recipients always read the flagged messages; the others 
they did not always study, but they did skim them. 
Distribution was usually made twice a day. Intercepts that had come 
in overnight went out in the morning, those processed during the day 
went out at the end of the afternoon. Especially important messages were 
delivered at once, often to the recipients' homes if late in the evening . 
Each agency sent its MAGIC copies on to the other with exemplary 
promptitude, despite a natural competition between them. 
As Bratton put it: "I was further urged on by the fact that if the Chief 
of Naval Operations ever got one of these things before General Marshall 
did and called him up to discuss it on the telephone with him, and the 
General hadn't gotten his copy, we all caught hell." (Marshall demurred: 
"I don't think I gave anybody hell much.") 
Delivery to the White House and the State Department incurred  
difficulties. Under an agreement of January 23, the Army and Navy at 
first alternated in servicing the two. The Army, however, discontinued its 
deliveries to the White House after its turn in May, partly because a 
military aide made a security bungle, partly because it felt that these 
diplomatic matters should go to the President through the State 
Department. The Navy continued its deliveries through the President's 
naval aide, Captain John R. Beardall, though once in the summer 
Kramer himself carried a particularly "hot" message—probably dealing 
with negotiations the next day—to Roosevelt . Near the end of September, 
a month originally scheduled for Army delivery, during which nothing 
was delivered to the White House, the President said he wanted to see 
the intercept information. In October naval intelligence sent him 
memoranda based on MAGIC, but on Friday , November 7, Roosevelt said 
he wanted to see MAGIC itself. Beardall told him that it was an Army 
month. The President replied that he knew that and that he was either 
seeing MAGIC or getting information on it from Hull, but that he still 
wanted to see the original intercepts. He feared that condensing them 
would distort their meaning . On Monday , a conference agreed that the 
Navy would furnish the White House with MAGIC and the Army the State 
Department. At 4:15 p.m., Wednesday , November 12, Kramer made the 
first distribution to the White House under this system. 
Thus, by the fall of 1941, MAGIC was being demanded at the topmost 
level of government. It had become a regular and vital factor in the 
formation of American policy . Hull, who looked upon MAGIC "as I would a 
witness who is giving evidence against his own side of the case," was "at 
all times intensely interested in the contents of the intercepts." The chief 
of Army intelligence regarded MAGIC as the most reliable and authentic 
information that the War Department was receiving on Japanese 
intentions and activities. The Navy war plans chief thought that MAGIC, 
which was largely diplomatic at this time, affected his estimates by about 
15 per cent. The high officials not only read MAGIC avidly and discussed it 
at their conferences, they acted upon it. Thus the decision to set up the 
command of United States Army Forces, Far East, which was headed by 
General MacArthur , stemmed in part from intercepts early in 1941 
showing that Germany was pressuring Japan to attack Britain in Asia in 
the hope of involving the United State in the war; on the basis of this 
information, the command was created in July to deter Japan by 
enhancing American prestige in the Western Pacific—and it is a fact that 
Japan did not then comply with Germany's wishes. 
The intricate mechanism of the American cryptanalytic effort pumped 
MAGIC to its eager recipients smoothly, speedily, and lavishly. Messages 
flew back and forth along the monitor channels as if along nerve cells. 
Intercepts poured into Washington with less and less of a time lag. S.I.S. 
and GY grew increasingly adept at solution; the translators picked out the 
important messages ever more surely. Bratton and Kramer hustled from 
place to place with their locked briefcases. MAGIC gushed forth in 
profusion. So effectively did the cryptanalytic agencies perform that 
Marshall could say of this "priceless asset ," this most complete and up-
to-the-minute intelligence that any nation had ever had concerning a 
probable enemy, this necromantic gift of the gods of which one could 
apparently never have enough, that "There was too much of it." 
 
2.  One Day of Magic:  II 
 
IN October the cabinet of Prince Konoye fell, and the Emperor summoned 
General Hideki Tojo to form a new government. One of the first acts of 
the new Foreign Minister, Shigenori Togo , was to call in the chief of the 
cable section. Togo, remembering a book that Herbert O. Yardley had 
written disclosing his 1920 solution of Japanese diplomatic codes, asked 
the cable chief, Kazuji Kameyama, whether their current diplomatic 
communications were secure. Kameyama reassured him. "This time," he 
said, "it's all right." 
With the assumption of total power by the militarists under Tojo, the 
last real hopes for peace died. Almost at once, events began to slide 
toward war. On November 4, Tokyo sent to her ambassadors at 
Washington the text of her proposal  B, which Togo described as 
"absolutely final." The ambassadors held it while they pursued other 
avenues, even though Tokyo, on November 5, told them that "Because of 
various circumstances, it is absolutely necessary that all arrangements 
for the signing of this agreement be completed by the 25th of this 
month." 
That same day, Yamamoto promulgated Combined Fleet Top Secret 
Order Number 1, the plan for the Pearl Harbor attack. Two days later, he 
set December 8 (Tokyo time) as Y-day and named Vice Admiral Chuichi 
Nagumo as Commander, First Air Fleet—the Pearl Harbor strike force. In 
the days that followed, the 32 ships that were to compose the force 
slipped, one by one, out to sea and vanished. Far from any observation , 
they headed north to rendezvous in a bay of barren Etoforu Island, one of 
the chill , desolate Kuriles north of the four main islands of Japan. 
Behind them the ships left their regular wireless operators to carry on an 
apparently routine radio traffic in their own "fists," or sending touch , 
which is as distinctive as handwriting. 
As the force was gathering , the Foreign Office, which knew only that 
the situation was tense and was never told in advance of the time, place, 
or nature of the planned attack, prepared on open -code arrangement as 
an emergency means of notification. Tokyo sent Circular 2353 to 
Washington on November 19: 
 
Regarding the broadcast of a special message in an emergency. 
In case of emergency ( danger of cutting off our diplomatic 
relations ), and the cutting off of international communications, the 
following warning will be added in the middle of the daily Japanese 
language short- wave news broadcast: 
1)   In  case  of  Japan-U.S.   relations   in   danger: HIGASHI NO 
KAZE AME ("east wind rain") 
2)   Japan-U.S.S.R.   relations:   KITA NO KAZE  KU-MORI ("north 
wind cloudy ") 
3)  Japan-British relations:  NISHE NO KAZE HARE  ("west wind 
clear") 
This signal will be given in the middle and at the end as a 
weather forecast and each sentence will be repeated twice. When 
this is heard please destroy all code papers, etc. This is as yet to be 
a completely secret arrangement. 
Forward as urgent intelligence. 
 
This open code related the winds to the compass points in which the 
named countries stood in regard to Japan: the U.S. to the east, Russia to 
the north, England to the west. Tokyo also set up an almost similar code 
for use in the general intelligence (not news) broadcasts. 
As the secret messages establishing these open codes whistled 
through the air, Navy intercept Station S at Bainbridge Island heard and 
nabbed them. The station teletyped them to GY, which identified them as 
J19 and began cryptanalysis. 
Many of the ships of the Pearl Harbor strike force had by then 
gathered in bleak Tankan Bay, where the only signs of human presence 
were a small concrete pier , a wireless shack, and three fishermen's huts. 
Snow covered the surrounding hills. In the gray twilight of November 21, 
the great carrier Zuikaku glided into the remote harbor to complete the 
roster . The force swung at anchor, awaiting the order to sortie. 
A few hours later, on November 20 (Washington time), the Japanese 
ambassador to the United States, Admiral Kichisaburo Nomura, and his 
newly arrived associate, Saburo Kurusu, presented Japan's ultimatum to 
Hull. It would have required the United States to reverse its foreign 
policy, acquiesce in further Japanese conquests, supply Japan with as 
much oil as she required for them, abandon China, and in effect 
surrender to international immorality. While Hull began drafting a reply, 
Tokyo cabled its ambassadors in message 812 that "There are reasons  
beyond your ability to guess why we wanted to settle Japanese-American 
relations by the 25th, but if within the next three or four days you can 
finish your conversations with the Americans; if the signing can be 
completed by the 29th (let me write it out for you— twenty -ninth); if the 
pertinent notes can be exchanged; if we can get an understanding with 
Great Britain and the Netherlands ; and in short if everything can be 
finished, we have decided to wait until that date. This time we mean it, 
the deadline absolutely cannot be changed. After that things are 
automatically going to happen." Two days later, Togo wirelessed: "The 
time limit set in my message No. 812 is in Tokyo time." The calendar had 
become a clock, and the clock had begun to tick. 
On November 25, Yamamoto ordered the Pearl Harbor strike force to 
sortie next day. At 6 a.m. on November 26, the 32 ships of the force—six 
carriers, two battleships, and a flock of destroyers and support vessels—
weighed anchor and sliced across the wrinkled surface of Tankan Bay. 
They steamed slightly south of east, heading into the "vacant sea"—the 
wintry North Pacific, whose wastes were undefiled by merchant tracks 
and whose empty vastness would swallow up the force. They had been 
ordered to return if detected before December 6 (Tokyo time); if 
discovered on December 7, Nagumo would decide whether or not to 
attack. Strict radio silence was enjoined. Aboard the battleship  Hiei, 
Commander Kazuyoshi Kochi, a communications officer for the force, 
removed an essential part of his transmitter and put it in a wooden box, 
which he used as a pillow . The force drove eastward through fog, gale  
winds, and high seas. No one saw them. 
 
Meanwhile, Hull, after a frantic week of drafting, consultations, and 
redraftings, had completed the American reply to Japan's proposal. It 
called upon Japan to withdraw all forces from China and Indochina and 
in return promised to unfreeze Japanese funds and resume trade. 
Nothing was said about oil. On November 26, the day that he handed it 
to Nomura, Tokyo circularized its major embassies with an open code. 
While the winds code envisioned abolition of all communication with the 
embassies, this new code—called the  INGO DENPO  ("hidden word") code —
was intended for a less critical situation. It seems to have been arranged 
at the request of the consul in Singapore in case code but not plain 
language telegrams were prohibited. It set up such equivalences as 
ARIMURA = code communications prohibited; HATTORI = relations between 
Japan and (name of  country ) are not in  accordance with  expectation ;3 
KODAMA = Japan; KUBOTA = U.S.S.R.; MINAMI =U.S.A.; and so on. "In order 
to distinguish these cables from others," Tokyo said, "the English word 
STOP will be added at the end as an indicator. (The Japanese word OWARI 
[end] will not be used.)" 
The next day, November 28, the Navy cracked the transposition for 
the J19 message of nine days earlier and learned of the winds code 
arrangement. The cryptanalytic agencies saw at once that this 
arrangement, which dispensed with the entire routine of coding, cabling, 
delivery, and decoding, could give several hours' advance warning of 
Japan's intentions. They erupted into activity to try to intercept it. This 
wrenched facilities away from the commercial (for Japanese diplomatic), 
naval, and radiotelephone circuits with which the agencies were familiar 
and put them on voice newscasts. 
The Army asked the Federal Communications Commission to listen  
for the winds code execute. Army stations at Hawaii and San Francisco 
tuned to the newscasts, as did Navy stations at Corregidor, Hawaii, and 
Bainbridge Island, and four or five along the Atlantic seaboard. Rochefort 
placed his four best language officers—Lieutenants Forrest R. Biard , J. 
R. Bromley, Allyn Cole, Jr., and G. M. Slonim—on a 24-hour watch on 
frequencies suggested by Washington and on others that his unit had 
found. The Dutch in Java and the British in Singapore listened. In 
Washington, Kramer made up some 3x5 cards for distribution to MAGIC 
recipients. They bore only the portentous phrases, "East Wind Rain: 
United States. North Wind Cloudy: Russia. West Wind Clear: England ." 
Soon plain-language intercepts were swamping GZ. Bainbridge ran up 
bills of $60 a day to send them in. Kramer and the other translators, 
already burdened, now had also to scan 100 feet of teletype paper a day 
for the execute; previously only three to five feet per week of plain 
language material had come in. The long strips were thrown into the 
wastebasket and burned after checking. Several times the GY watch 
officers telephoned Kramer at his home at night to ask him to come to 
the office and check a possible execute. It always proved false. 
Meanwhile, other signs of increasing tension were not lacking. On the 
29th, Baron Oshima in Berlin reported that the German Foreign 
Minister, Joachim von Ribbentrop, had told him, "Should Japan become 
engaged in a war against the United States, Germany, of course, would 
join the war immediately." Next day, Tokyo replied, "Say very secretly to 
them that there is extreme danger that war may suddenly break out 
between the Anglo-Saxon nations and Japan through some clash of arms 
and add that the time of the breaking out of this war may come quicker 
than anyone dreams." Both these messages were translated on December 
1, and Roosevelt considered the latter so important that he asked for a 
copy of it to keep. Kramer, after paraphrasing it for security's sake, gave 
him one. 
 
At Pearl Harbor, Rochefort had just been presented with an 
unpleasant confirmation of that tautening situation. The Japanese fleet 
reassigned its 20,000 radio call-signs at midnight, December 1—only 30 
days after the previous change. It was the first time in Rochefort's 
experience that a switch had occurred so soon after a previous one. 
The one on November 1 had been expected; it had followed by the 
usual six months the regular spring call-sign shift. With the facility born 
of long experience, Rochefort's Combat Intelligence Unit identified in 
fairly rapid order the senders and receivers of a large percentage of the 
traffic. The unit observed the rising volume and southward routing of 
messages on the 200 radio circuits of the Japanese Navy. This fitted in 
almost perfectly with the widely known Japanese buildup for what the 
world thought was a strike at Siam or Singapore. By the third week in 
November, the unit had sensed the formation of a Third Fleet task force 
and its imminent departure in the direction of those areas. Aircraft 
carriers were not addressed during this buildup, nor did they transmit. 
To Rochefort, the situation shaped up like those of February and July, 
when Japanese fleet units moved south to support the takeover in 
French Indochina while the carriers remained in home waters as a 
reserve. They were there, he felt, to protect the exposed flank of the 
Japanese forces from the American fleet, which, from its bases at Cavite 
and Pearl, could sever the supply lines of the aggressor. 
Rochefort's view was shared by fleet intelligence officer Layton. He 
knew that the two main carrier divisions had not appeared in the traffic 
for at least two weeks, and maybe three. He suspected their presence in 
home waters, but since he lacked positive indications of it, he omitted his 
presumptions from a report on the Japanese fleet that he submitted to 
Kimmel on December 1. Whereupon, Layton recalled: 
 
Admiral Kimmel said, "What! You don't know where Carrier 
Division 1 and Carrier Division 2 are!" 
I replied, "No sir, I do not. I think they are in home waters, but I 
do not know where they are. The rest of these units, I feel pretty 
confident of their location ." Then Admiral Kimmel looked at me, as 
sometimes he would, with somewhat a stern countenance and yet 
partially with a twinkle in his eye, and said: 
"Do you mean to say that they could be rounding Diamond 
Head and you wouldn't know it?" or words to that effect. My reply 
was that "I hope they would be sighted before now," or words to 
that effect. 
 
On the same day that Layton gave his report to Kimmel, the Office of 
Naval Intelligence produced a memorandum of "Japanese Fleet 
Locations" that Layton, when he saw it, considered as "dotting the i's and 
crossing the t's" of his own estimates. It placed Akagi and Kaga (Carrier 
Division 1), and Koryu and Kasuga in southern Kyushu waters, and 
Soryu and Hiryu (Carrier Division 2) and Zuikaku, Shokaku, Hosho, and 
Ryujo  at the great naval base of Kure . All this was just a more precise 
way of saying "home waters." 
These estimates were based on the November observations. The call-
sign change of December 1 obliterated the intricate communication 
networks that the radio intelligence units had so painstakingly built up 
and forced them to begin anew. The Japanese bedeviled them with new 
communication-security measures . Dispatches were sent “on the 
umbrella "—broadcast to the fleet at large and copied by all ships. This 
sort of blanket coverage made identification difficult. Multiple addresses 
were used. They sent dummy traffic, which, however, did not confuse the 
listeners. Just before the change, the communicators passed many old 
messages. Rochefort's unit spotted them, and guessed that they were 
attempts either to pad the volume or to get through to the addressee 
before the change caused routing difficulties. 
On December 2, after only two days of analyzing the new calls, 
Rochefort's unit stated in its Communications Intelligence Summary: 
"Carriers—Almost a complete blank of information of the Carriers today. 
Lack of identifications has somewhat promoted this lack of information. 
However, since over two hundred service calls have been partially 
identified since the change on the first of December and not one carrier 
call has been recovered, it is evident that carrier traffic is at a low ebb." 
In the next day's summary appeared the last mention of carriers before 
December 7, and it was rather negative : "No information on submarines 
or carriers." 
Other messages, however, clearly indicated the drive to the south, 
which Japan made no attempt to conceal. Twice before, Rochefort, 
Fabian, Layton, and O.N.I, had seen exactly the same conditions , and 
twice before their reasoning that the carriers were being held in empire 
waters had been proved right. Now, they thought, they were seeing it 
happen again. Temporarily oblivious to the possibility of a surprise 
attack on Pearl Harbor, they watched the forces moving against Malaya 
as hypnotically as a conjuror's audience stares at the empty right hand 
while the left is pulling the ace out of a sleeve. 
 
American preconceptions were reinforced by two PURPLE messages of 
December 1, which the Navy read that same day. In the first, Tokyo 
directed Washington: "When you are faced with the necessity of 
destroying codes, get in touch with the naval attache's office there and 
make use of chemicals they have on hand for this purpose . The ATTACHÉ 
should have been advised by the Navy Ministry regarding this." Five days 
earlier, the cryptanalysts had read Tokyo's detailed instructions on how 
to destroy the PURPLE machine in an emergency. These two code-
destruction messages appeared to be just precautionary measures in a 
tense situation, and this impression was strengthened by the second 
message of December 1. It seemed to virtually announce a Japanese 
invasion of British and Dutch possessions and to relegate conflict with 
the United States to a subsequent date: "The four offices in London, 
Hong - kong , Singapore and Manila have been instructed to abandon the 
use of the code machines and to dispose of them. The machine in 
Batavia has been returned to Japan. Regardless of the contents of my 
circular message #2447 [which MAGIC did not have], the U.S. (office) 
retains the machines and the machine codes." American officials 
breathed easier. The messages appeared to give the United States a bit 
more of what it needed most—time, time to build up its pitifully weak  
Army and Navy. 
 
While the world gazed with tunnel vision toward Southeast Asia, and 
American radio intelligence envisioned the Japanese carriers in home 
waters, six of them—Akagi, Kaga, Hiryu, Soryu, Shokaku, and Zuikaku—
were in fact butting eastward through the high winds and waves of the 
vacant sea. Late in the afternoon of December 2, Tokyo time, the force 
picked up, apparently on a blanket broadcast, an electrifying open-code 
message intended for it: NIITAKA-YAMA NOBORE (" Climb Mount Niitaka"). It 
informed the strike force that the decision for war had been made and 
directed it to proceed with attack. Niitaka-yama, also known as Mount 
Morrison, is a peak on Formosa whose 12,956- foot elevation made it the 
highest point of what was then the Japanese empire. The symbolism 
could not have been lost on the officers. The force refueled from its 
tankers. 
 
Earlier that day, the Japanese consulate in Honolulu had received 
Circular #2445 in J19, relayed by Washington from Tokyo: 
 
Take great pains that this does not leak out. You are to take the 
following measures immediately: 
1.  With the exception of one copy each of the O [PA-K2] and the 
L [LA] codes, you are to burn all telegraph codes (this includes the 
codebooks for communication between the three departments 
[HATO] and those for use by the Navy). 
2.  As soon as you have completed this operation, wire the one 
word  HARUNA . 
3.  Burn all secret records of incoming and outgoing telegrams. 
4. Taking care not to arouse outside suspicion, dispose of all 
secret documents in the same way. 
Since these measures are in preparation for an emergency, keep 
this within your consulate and carry out your duties with calmness 
and care. 
 
The codes were duly burned, including the TSU, or J19, in which the 
circular was transmitted. That evening Kita sent HARUNA.  Henceforth  the  
consulate  code  secretary, Samon Tsukikawa, would have to transmit 
the spy messages of Yoshikawa, alias Morimura, in the simpler PA-K2. 
The first such message arranged four signaling systems by which a spy 
might report on the condition of the ships in Pearl Harbor. The 
arrangement had been submitted to Yoshikawa by an Axis spy in Hawaii, 
Bernhard Julius Otto Kühn.  Nazi Propaganda Minister Josef Goebbels 
had transferred him to the islands in 1935 after a contretemps with 
Kühn's daughter Ruth, who had become Goebbels' mistress when she 
was 16. In his signaling system, Kühn stipulated that numbers from 1  
to 8 would mean such things as A number of carriers preparing to sortie 
(which was 2) and Several carriers departed between 4th and 6th (which 
was 7). Then he arranged that bonfires, house lights shown at certain 
times and places, or want ads broadcast over radio station KGMG would 
mean certain numbers. For example, 7 would be represented by two 
lights shown in the window of a house on Lanikai Beach between 2 and 3 
a.m., or by two sheets between 10 and 11 a.m., by lights in the attic  
window of a house in Kalama between 11 and 12 p.m., or by a want ad 
offering a complete chicken farm for sale and listing P.O. Box 1476. If all 
these failed, a bonfire on a certain peak of Maui Island between 8 and 9 
p.m. would indicate 7. The purpose of the system was to eliminate 
dangerous personal contacts between Kühn and the Japanese. Kühn 
tested it on December 2, found that it worked, and passed it to 
Yoshikawa. He had it encoded  (in PA-K2)   and sent to Tokyo in two long 
parts on December 3. 
It was now the third day of the month in which the Japanese 
consulate gave its cable business to R.C.A. Following Sarnoff's 
instructions, George Street , district manager of the firm , had had the 
Japanese consulate messages copied on a blank sheet of paper with no 
identification of the sender or addressee. About 10 or 11 a.m., December 
3, Mayfield called at the branch office and Street slipped him a blank 
envelope containing the messages. As soon as Mayfield returned to the 
District Intelligence Office, he had a messenger bring them down to 
Rochefort. 
In Washington that Wednesday, the Signal Intelligence Service solved 
a PURPLE message from Tokyo—and the readers of MAGIC, who only two 
days earlier had been lulled by the supposition that Japan might 
temporarily spare the United States, were stunned by the realization that 
the arrow of war might be loosed momentarily. For the message ordered 
the Washington embassy to "burn all [codes] but those now used with 
the machine and one copy each of o code [PA-K2] and abbreviating code 
[LA]. . . . Stop at once using one code machine unit and destroy it 
completely . . . wire . . . HARUNA." Under Secretary of State Welles saw it 
and felt that "the chances had diminished from one in a thousand to one 
in a million that war could then be avoided." When the President's naval 
aide, Beardall, brought the message to Roosevelt, he said in substance, 
"Mr. President, this is a very significant dispatch." After the Chief 
Executive had read it carefully, he asked Beardall, "When do you think it 
will happen?"—referring to the outbreak of war. "Most any time," replied 
the naval aide, who thought that the moment was getting very close . 
At the Japanese embassy at 2514 Massachusetts Avenue, the code 
clerks were executing these destruction orders. The code room stood at 
the southeast corner of the embassy, with windows overlooking the 
embassy parking lot and another legation next door. Half a dozen desks 
clustered in the middle of the room. Two cipher machines waited on 
desks against the west wall and a third, broken, rested in the walk -in 
safe . In utter disregard of the regulations promulgated for the security of 
communications, the embassy had hired an elderly Negro janitor named 
Robert to dust and clean the code room and its supersecret furnishings 
each day. The code clerks did make some obeisance to the security 
regulations by not allowing him in the room unless some Japanese were 
in it. But the situation was, to say the least, ironical. While the Japanese 
Foreign Office was exercising almost superhuman security precautions 
and American cryptanalysts were suffering nervous breakdowns to solve 
the PURPLE machine, an American citizen was running his duster over 
tables on which stood the intricate machines that were the vortex of this 
silent struggle . 
But just as the Japanese seemed not to have given serious thought to 
the possibility of Robert's being a spy, so the Americans seemed to have 
given no serious thought to the possibility that a spy might have been 
insinuated into the Japanese embassy to ease their cryptanalytic burden. 
Of course, even if they had thought about it, they might have rejected the 
idea , for discovery of the spy would have meant an automatic change of 
codes. The danger of this was much less if the systems were read 
through cryptanalysis. 
The paper codes of the Japanese consisted of folders whose four or six 
pages could be opened into a single long sheet. Embassy Counselor 
Sadao Iguchi , who was in charge of the code room, directed telegraph 
officer Masana Horiuchi and code clerks Takeshi Kajiwara, Hiroshi Hori, 
Juichi Yoshida, Tsukao Kawabata and Kenichiro Kondo in the burning of 
the paper codes. Demolition of the code machine was more complicated, 
and followed the guidelines transmitted recently by the Foreign Office. 
The machines were dismantled with a screwdriver, hammered into 
unrecognizability, and then dissolved in acid from the naval attache's 
office to destroy them thoroughly. Some of these operations were carried 
out in the gardens of the embassy; so when Bratton, who had read the 
code-destruction intelligence, sent an officer to the embassy to check, he 
obtained immediate confirmation. 
Now the American officials realized the ominous meaning of the 
HARUNA messages that had been intercepted as they were sent from New 
York, New Orleans , and Havana and that had been received just that day 
in S.I.S. The Army and Navy high command universally regarded the 
destruction of codes as virtual certainty that war would break out within 
the next few days. As Stark's deputy put it: "If you rupture diplomatic 
negotiations you do not necessarily have to burn your codes. The 
diplomats go home, and they can pack up their codes with their dolls 
and take them home. Also, when you rupture diplomatic negotiations 
you do not rupture consular relations. The consuls stay on. Now, in this 
particular set of dispatches they not only told their diplomats in 
Washington and London to burn their codes, but they told their consuls 
in Manila, in Hong Kong, Singapore, and Batavia to burn their codes and 
that did not mean a rupture of diplomatic relations; it meant war." 
A few hours after the code-destruction MAGIC reached Stark, he 
dispatched the electrifying news to Kimmel and Hart : 
 
Highly reliable information has been received that categoric and 
urgent instructions were sent yesterday to Japanese diplomatic 
and consular posts at Hongkong X Singapore X Batavia X Manila X 
Washington and London to destroy most of their codes and ciphers 
at once and to burn all other important confidential and secret 
documents X 
 
He followed this five minutes later with another message: 
 
Circular twenty four forty four from Tokyo one December 
ordered London X Hongkong X Singapore and Manila to destroy 
PURPLE machine XX Batavia machine already sent to Tokyo XX 
December second Washington also directed destroy PURPLE X all but 
one copy of other systems X and all secret documents XX British 
Admiralty London today reports embassy London has complied 
 
In Washington urgency drove out all thoughts of security. The strict 
injunction against ever mentioning MAGIC was completely overlooked. 
When Kimmel got the message, he asked Layton what "PURPLE" was. So 
tight had security been that neither of them knew. They checked with 
Lieutenant Herbert M. Coleman, the fleet security officer, who told them 
that it was a cipher machine similar to the Navy's. 
 
At 8:45 p.m. that night, Thursday, December 4, the watch officer of 
the F.C.C.'s Radio Intelligence Division telephoned the Office of Naval 
Intelligence to ask if it could accept a certain message. The O.N.I. officer 
was not sure and said he would call back. At 9:05 GY watch officer 
Brotherhood called the F.C.C. and was given a Japanese weather report 
that sounded like something the F.C.C. man had been told to listen for. 
He read it to Brotherhood: "Tokyo: today—wind slightly stronger, may 
become cloudy tonight ; tomorrow-—slightly cloudy and fine weather. 
Kanagawa prefecture: today—north wind cloudy; from afternoon—more 
clouds. Chiba prefecture: today—north wind clear, may become slightly 
cloudy. Ocean surface: calm." 
Brotherhood was relieved that it included nothing about EAST WIND 
RAIN, which would have meant the United States, but in any case this 
message seemed to lack something that would have been required in a 
true execute. For one thing , the phrase NORTH WIND CLOUDY, which would 
have meant Russia, was not repeated twice. Nevertheless, Brotherhood 
telephoned Rear Admiral Leigh Noyes, director of naval communications, 
who remarked that he thought the wind was blowing from a funny 
direction. The concensus was that it was not a genuine execute, and the 
search continued. 
 
In Tokyo, where it was December 5, Foreign Minister Togo received 
representatives of the Army and Navy general staffs. A general and an 
admiral wanted to discuss the delicate matter of the precise timing of 
Japan's final note to the United States. Drafted in English by the director 
of the Foreign Office's American bureau, the note had been approved by 
the Liaison Conference, a six-man war cabinet, at its meeting the day 
before. It rejected Hull's offer of the 26th and concluded: "The Japanese 
Government regrets to have to notify hereby the American Government 
that in view of the attitude of the American Government it cannot but 
consider that it is impossible to reach an agreement through further 
negotiations." 
Article I of the 1907 Hague Convention governing the laws of war 
provides that ". . . hostilities . . . must not commence without previous 
and explicit warning, in the form either of a reasoned declaration of war 
or of an ultimatum with conditional declaration of war." Togo had 
suggested to the Liaison Conference that the note was far stronger than 
an ultimatum and that to include a specific declaration of war would be 
"merely to reiterate the obvious." The conferees had gratefully acceded to 
this casuistry, since it enabled them to comply with the prior -notification 
requirement without endangering the surprise of the attack. Since the 
Hague Convention does not specify how long in advance such notification 
must be given, Premier Tojo and the other conferees thought to shave the 
time as much as possible. Dawn in Hawaii was about noon m 
Washington. The Liaison Conference had tentatively set 12:30 p.m., 
Sunday, December 7 (Washington time), as the time of delivery of the 
note. 
But when the two military men called upon Togo the next day to fix 
the exact time, Vice Admiral Seiichi Ito, vice chief of the naval general 
staff, told the foreign minister [Togo later wrote] "that the high command 
had found it necessary to postpone presentation of the document thirty 
minutes beyond the time previously agreed upon, and that they wanted 
my consent thereto. I asked the reason for the delay , and Ito said that it 
was because he had miscalculated. ... I inquired further what period of 
time would be allowed between notification and attack; but Ito declined 
to answer this, on the plea of operational secrecy. I persisted, demanding  
assurance that even with the hour of delivery changed from twelve-thirty 
to one there would remain a sufficient time thereafter before the attack 
occurred; this assurance Ito gave. With this—being able to learn no 
more—I assented to his request. In leaving, Ito said: 'We want you not to 
cable the notification to the Embassy in Washington too early.'" In this 
demand lay the seeds of Japan's juridical culpability. 
 
Yoshikawa, in Honolulu, had continued sending his ship-disposition 
reports after the switch to PA-K2. They were an odd melange of accuracy , 
error , and outright falsehoods. On December 3, for example, he correctly 
reported that the liner  Lurline had arrived from San Francisco but stated 
that a military transport had departed when no such thing had occurred. 
The next day he informed Tokyo about the hasty departure of a cruiser of 
the Honolulu class; no such ship either entered or cleared the harbor on 
the 4th. Then, on the 5th, he cabled that three battleships had arrived in 
Pearl Harbor, making a total—which he reported with deadly accuracy—
of eight anchored in the harbor. His messages, sent over Kita's signature, 
were decoded in the Foreign Office and routed to the North American 
section, where Toshikazu Kase passed them immediately to the Navy 
Ministry. Here they were redrafted, encoded in a naval code, and 
transmitted on a special frequency not normally used by the Navy and 
without any direct address to the Pearl Harbor strike force. Commander 
Koshi decoded it and brought to his chief this latest information. 
The communication-security precautions paid off. Whether or not the 
messages slipped by the American radio monitors in Hawaii mattered 
little. Mere interception would not have helped much. The messages bore 
no external indication of their intended recipient, and they could not 
have been read. Rochefort's attack on Japanese naval codes had 
achieved some minor successes in late October and November, but he 
could read only about 10 per cent of the naval traffic, and much of this 
consisted of weather and other minor systems. The information obtained, 
Rochefort said, "was not in any sense vital." Cavite was spottily reading 
JN25 messages—which revealed nothing about Pearl Harbor—until 
December 4, when the superencipherment was suddenly changed. As a 
message that moved on the monitor channel put it: "Five numeral 
intercepts subsequent to zero six hundred today indicate change of 
cipher system including complete change differentials and indicator 
subtracters X All intercepts received since time indicated checked against 
all differentials three previous systems X No dupes." Corregidor was not 
to get the initial break into the new superencipherment until December 
8. And the only other system in which the Yoshikawa messages might 
have been forwarded—the flag officers' system—remained unsolved. 
A possibility of warning was opened at the source, however, when 
Yoshikawa's original messages became available to Rochefort's unit. 
Mayfield had picked up another batch of cables in the surreptitious 
fashion from Street on Friday morning and immediately sent them down 
to Rochefort's unit by messenger. Solving them was not part of its duty,4 
but when a superior officer and colleague asks one to do a favor , it is 
hard to say no. Rochefort assigned the messages to Chief Radioman 
Farnsley C. Woodward, 39, who had had some experience with Japanese 
diplomatic codes at the Shanghai station from 1938 to 1940. He had 
some help from Lieutenant Commanders Thomas H. Dyer, Rochefort's 
senior cryptanalyst, and Wesley A. Wright, Dyer's assistant. Although the 
unit was not working on the diplomatic systems, it had information on 
them in the Navy's R.I.P.s, or Radio Intelligence Publications, with which 
all radio intelligence units were supplied. The R.I.P. gave, however, only 
the PA code list, leaving the onerous reconstruction of the current K2 
transposition to the cryptanalyst. The half-dozen or so dispatches, plus  
some in LA, reached Woodward about 1:30 or 2 p.m. Friday, and he 
immediately began the first of a series of 12- and 14-hour days to read 
them. He had no difficulty with the LA messages, which were translated 
into English by Marine Corps Captain Alva Lasswell, but these yielded 
"nothing but junk ." The K2, however, eluded him, and he worked on it far 
into the night. 
 
In Tokyo it was a little after 1 p.m. on Saturday, December 6. The 
Japanese reply to Hull's note of the 26th had recently been sent to the 
cable room of the Foreign Ministry for transmission to the embassy in 
Washington. Kazuji Kameyama, the cable chief, broke it into fourteen  
approximately equal parts to facilitate handling and ordered these 
enciphered on the 97-shiki O-bun In-ji-ki. He also enciphered a shorter 
" pilot " message from Togo alerting the embassy that the reply was on the 
way and instructing it "to put it in nicely drafted form and make every 
preparation to present it to the Americans just as soon as you receive 
instructions." At 8:30 p.m., the pilot message was telegraphed from the 
cable room to Tokyo's Central Telegraph Office, from where, 45 minutes 
later, it was radioed to the United States. Bainbridge Island intercepted it 
and relayed it to OP-20-G. By five minutes past noon on Saturday, 
December 6 (Washington time), OP-20-o had delivered the teletype copy 
to S.I.S., which promptly ran it through the PURPLE machine. By 2 p.m. 
Bratton had it, translated and typed. An hour later it was in the hands of 
the Army distributees. S.I.S. had officially closed at 1 p.m. and was not 
due to reopen until 6, when it was to go on 24-hour status. But this 
notification of the imminent receipt of the long-awaited reply to Hull's 
note of the 26th led to telephoning employees Mary J. Dunning and Ray 
Cave about 2:30 and asking them to report to work. By 4 both were 
there. 
In Tokyo, Kameyama had released the first 13 parts of the Japanese 
note to the Central Telegraph Office. Following the instructions of the 
American bureau, he retained the crucial 14th part, which broke off 
negotiations. Shortly after 10 p.m., commercial radio began sending the 
13 parts to Washington. Most of them took less than ten minutes to 
transmit, but even though two transmitters were used, it was not until 
two minutes before 2 a.m. that the tail of the last part had gone . 
Bainbridge, of course, was listening, and it picked the parts up in this 
order: 1, 2, 3, 4, 10, 9, 5, 12, 7, 11, 6, 13, 8. One batch arrived by 
teletype at OP-20-G at eleven minutes before noon, Saturday, December 
6, Washington time, and the other at nine minutes of 3 that afternoon. 
Though it was Saturday, December 6, an even date and hence an Army 
date of responsibility, the Navy handled the dispatches because it knew 
that S.I.S. was not expected to work that afternoon, and it considered the 
intercepts of great importance. Decryptment did not go very smoothly, 
however. Something seemed to be in error. GY knew the key, but it was 
producing garbles every few letters. The cryptanalysts tried to correct 
them. 
Meanwhile, a decode into Japanese of the long PA-K2 message that 
Yoshikawa had sent concerning Kuhn's visual-signal system for Hawaii 
was placed on the desk of Mrs. Edgers in GZ. "At first glance," she said, 
"this seemed to be more interesting than some of the other messages I 
had in my basket , and so I selected it and asked one of the other men, 
who were also translators working on other messages, whether or not 
this shouldn't be done immediately and was told that I should and then I 
started to translate it. Well, it so happened that there was some mistake 
in the message that had to be corrected and so that took some time. That 
was at 12:30 or perhaps it was a little before or after 12:30; whatever 
time it was, we were to go home. It being Saturday, we worked until 
noon. I hadn't completed it, so I worked overtime and finished it, and I 
would say that between 1:30 and 2 was when I finished my rough draft  
translation." Mrs. Edgers left it in the hands of Chief Yeoman Bryant. But 
the message was still not entirely clear, and she had not yet had enough 
experience for her translations to be sent out without further checking. 
Kramer, busy with the 13 parts, did not examine it in detail. 
To speed processing of the 13 parts, GY, learning that some people 
were in S.I.S., sent over parts 1 and 2. But when Major Doud of S.I.S. 
ordered Miss Cave to OP-20-G to help in the smooth typeups, the two 
parts were returned to GY for solution there, probably because of the 
garbles. But other messages also coming in were retained by S.I.S. 
At 3 o'clock, Kramer, in GZ, had checked with GY to find out whether 
any more Tokyo traffic had come in before releasing his translators for 
the day. Since the critical matter of a diplomatic note is often found in 
the last sentences , GY broke down the last part intercepted for him. The 
first part of the first line indicated in Japanese that this was part 8 of a 
14-part message. After about three lines of Japanese text in the 
preamble, the message came out in English, just as the Foreign Office 
had sent it. Kramer could let his translators go home. Interspersed 
throughout the English text were many of the three-letter codewords 
indicating punctuation, paragraphing, and numbering, but these posed 
no problem since they had been recovered long ago. 
At 4 o'clock, when Linn took over the GY watch, the garbles still had 
not been cleared. He decided to start from the very beginning, to check 
the key, find what was wrong , and redecrypt the messages rather than to 
try to guess at the garbled letters and possibly make serious errors that 
would distort the sense. Discarding all the previous work caused a 
serious jam on the Navy's one PURPLE machine, and about 6 p.m. GY 
again called on S.I.S. for help. Parts 9 and 10 were sent over; an hour 
later, the decrypts came back in longhand. By 7:30, the last of the 13 
parts was being decrypted. 
Not all the garbles had been scrubbed out. Part 3 had a 75-letter 
smudge that could not be read at all, Part 10 a 45-letter blur , and Part 
11 one of 50 letters. Part 13 went awry in two patches. One deciphered 
as andnd and the other as chtualylokmmtt; GY thought the first should be 
and as and the second China, can but.5
In the Japanese embassy, about a mile away, the code clerks had 
completed deciphering the first seven or eight parts of the message by 
dinnertime. Then they all repaired to the Mayflower Hotel for a farewell  
dinner for Hidenari Terasaki, head of Japanese espionage for the western 
hemisphere, who had been ordered to another post. 
 
While they were enjoying themselves, American code clerks at the 
Department of State were at work encoding a personal appeal for peace 
from the President of the United States to the Emperor of Japan. This 
had been off again, on again since October, Roosevelt apparently wishing 
to save it for a last resort . Now he decided that the time had come. The 
message was on its way by 9 o'clock. It traversed the 7,000 miles to 
Tokyo in an hour. 
But it took ten hours to get from the Central Telegraph Office to the 
American embassy. 
 
As the President was addressing a message of peace to the Emperor, 
the men of the Japanese strike force were listening to a message of war. 
Shortly before, Admiral Nagumo had topped off the fuel tanks of his 
combat ships for the final dash. His crews waved farewell to the slow-
moving tankers. Now the officers read a stirring message from Yamamoto 
to all hands: "The moment has arrived. The fate of the empire is at stake . 
Let every man do his best." Banzais rent the air. Up the mast of Akagi 
fluttered the very flag that had flown at Japan's great naval victory over 
Russia in 1905. It was a moment of great emotion. Nagumo altered 
course to due south and bent on 26 knots. Through a mounting sea, the 
battle force plunged toward its target. 
 
Lovely, peaceful, that target lay "open unto the fields, and to the sky," 
oblivious to the onrushing armada of destruction. And as it increased its 
speed, more information for its mission was starting on its way. The 
R.C.A. office was time-stamping "1941 Dec 6 PM 6 01" on a message from 
the consulate. It was signed "Kita" but it came from Yoshikawa. It was 
brief (only 44 groups) and cheap ($6.82), but it reported that "(1) On the 
evening of the 5th, the battleship Wyoming and one sweeper entered 
port. Ships at anchor on the 6th were: 9 battleships, 3 minesweepers, 3 
light cruisers, 17 destroyers. Ships in dock were: 4 light cruisers, 2 
destroyers. Heavy cruisers and carriers have all left. (2) It appears that 
no air reconnaissance is being conducted by the fleet air arm." 
Yoshikawa was, as usual, partly right and partly wrong. He mistook Utah 
for Wyoming. His figure on the battleships was correct, but in harbor that 
afternoon were 6 light and 2 heavy cruisers, 29 destroyers, 4 
minesweepers, 8 minelayers, and 3 seaplane tenders. With this message 
Yoshikawa completed his assignment. It was the last cable sent by the 
Japanese consulate in Hawaii for many years. 
 
[Codebreakers 050.jpg]
On the eve of Pearl Harbor, Takeo Yoshikawa  sends  his final message over Consul 
Kita's signature, using the PA-K2 code, to report that the U.S. fleet is still in port 
 
By 8:45 p.m. in Washington, the 13 parts had been typed in smooth 
copies and put up in folders. Kramer began telephoning the recipients to 
find out where they were so he could bring the MAGIC to them. He also 
called his wife , Mary, who agreed to chauffeur him during his deliveries. 
They reached the White House first, at about 9:15. The naval aide, 
Beardall, had told the President that some MAGIC would be delivered that 
evening, and at about 4 p.m. he had ordered his communications 
assistant, Lieutenant Lester R. Schulz , to stand by and bring it to the 
President. Schulz was waiting in Beardall's small office in the corner of 
the basement mail room in the White House when Kramer arrived. The 
Roosevelts had been entertaining at a large dinner party, but the 
President had excused himself. Schulz obtained permission to bring the 
MAGIC to the President, and an usher accompanied him to the oval study 
on the second floor and announced him. Roosevelt was seated at his 
desk. Only Harry Hopkins was with. him. Schulz unlocked the briefcase 
with the key that Beardall had given him, removed the sheaf of MAGIC, 
and handed it to the President. He read the 13 parts in about ten 
minutes while Hopkins paced slowly up and down. Then Hopkins read 
them. The  13th part rejected Hull's offer, and when Hopkins had passed 
the papers back to the President, Roosevelt turned to him and said, in 
effect, "This means war." Hopkins agreed, and for about five minutes they 
discussed the situation, the deployment of Japanese forces, the 
movement towards Indochina, and similar matters. The President 
mentioned his message to Hirohito . Hopkins remarked that it was too 
bad that the United States could not strike the first blow and prevent any 
kind of surprise in the inevitable war. 
"No," the President said in effect, "we can't do that. We are a 
democracy and a peaceful people." He raised his voice: "But we have a 
good record." He tried unsuccessfully to get Admiral Stark on the 
telephone, deciding against having him paged at the National Theater for 
fear of causing undue alarm . 
The President then returned the papers to Schulz and, about half an 
hour after he had entered the study, Schulz left. He found Kramer seated 
at one of the long tables in the mail room. Schulz gave him the pouch  
and soon thereafter went home. Kramer, however, continued to the 
Wardman Park Hotel, where Secretary Knox had a suite . For about 
twenty minutes, while Kramer chatted with Mrs. Knox and the acting  
manager of Knox's Chicago Daily News, the Secretary read the 13 parts. 
He agreed with Kramer, that, even incomplete, it pointed to a termination 
of negotiations. He went into another room to make some telephone calls, 
and when he came out he told Kramer to bring the latest MAGIC to a 
meeting that had been arranged for 10 a.m. the next morning with 
Stimson and Hull in the State Department. (Bratton had delivered the 13 
parts to the night duty officer at State at 10 p.m., admonishing him to 
get them to Hull at once.) Knox returned the intercepts to Kramer, who 
then went to the home of Rear Admiral Theodore S. Wilkinson , director of 
naval intelligence, where Beardall and Army intelligence chief Brigadier  
General Sherman Miles happened to be dinner guests. All three studied 
the intercept in a room away from the other guests, Beardall reading 
from an extra copy that Kramer had. They too seemed to feel that 
negotiations were coming to an end. 
It was after midnight when Kramer left the Wilkinson house. His wife 
drove him back to the Navy Department, where he put the MAGIC back in 
his safe in GZ and checked to see if the 14th part had yet come in. It had 
not. Finally he went home himself. 
In S.I.S., meanwhile, the new teletype that would expedite the 
forwarding of intercepts was being set up in the " cage ," the barred room 
where PURPLE traffic was processed. Monitor Post 2 was requested to send 
in some intercepts as a test. In San Francisco, Harold W. Martin, the 
noncom in charge, punched onto the teletype tape the intercepts that the 
post had picked up since airmailing in the bulk of the day's material, as 
well as the earlier ones. Among the later ones was Yoshikawa's final 
message, which thus became one of the first to move on the direct wire 
as a real, nontest item. S.I.S. received it a little after midnight. But PA-K2 
was a low-priority system, and the message had originated in a consular 
office. It was set aside to be worked on later. 
Besides , S.I.S. had more important things to worry about. Like OP-20-
O, it was going frantic in a search for the 14th part. Captain Robert E. 
Schukraft, head of the intercept section, and Frank B. Rowlett, the 
civilian cryptanalyst in charge of the Japanese diplomatic solutions, 
checked and rechecked to see whether one of the stations had picked it 
up and had somehow neglected to forward it. The message preambles 
had said that it existed, but they could find no trace of it. Neither 
suspected that the Japanese Foreign Office had deliberately held up 
transmission of this final conclusive part for security's sake. 
Neither did the code clerks at the Japanese embassy. They had 
returned from Terasaki's party about 9:30, and by midnight had 
completed deciphering of the 13 parts. While they waited for the final 
section, they busied themselves by disposing of the remnants of the 
cipher machine they had destroyed the night before. But they did 
nothing to fulfill the orders of the pilot message to prepare the dispatch 
for immediate presentation. 
Finally, fourteen hours after the last part of the previous 13 parts had 
been transmitted, the Foreign Office released the crucial 14th part that 
broke off negotiations. At 4 p.m., Tokyo time, it ordered it transmitted via 
both R.C.A. and Mackay Radio & Telegraph Company to ensure its 
correct reception . An hour and a half later, it wired to the Central 
Telegraph Office the coded message ordering the 1 p.m. delivery of the 
14-part note. This too was sent via the two companies. 
As usual, the indefatigable ear of Bainbridge Island detected the 
ethereal pulses of both messages. It picked up the Mackay transmission 
of the 14th part between 12:05 and 12:10 a.m., December 7, local time, 
and the even briefer one o'clock message between 1:28 and 1:37 a.m. It 
teletyped them to GY in a single transmission, the 14th part as serial No. 
380 of Station S, the one o'clock as No. 381. Brotherhood, who was GY 
watch officer, ran them through the PURPLE machine. He evidently had 
some trouble with the 14th part, for it took an hour to break. But by 4 
a.m. he had it in English. The three-letter codegroups were quickly 
translated into punctuation; the message would need little more than 
typing. The one o'clock message, however, turned out to be in Japanese. 
He sent it to S.I.S. for translation, knowing that translators were on duty 
because S.I.S. was beginning its round-the-clock tours. It was a little 
past 5 a.m., Washington time. 
In the embassy of Nippon, the code clerks who had waited all through 
the night for the 14th part were, on Counselor Iguchi's advice, being sent 
home. Just as they were climbing wearily into their beds, the naval 
attaché arrived and found the mailbox stuffed with cablegrams. The duty 
officer telephoned the clerks at their homes about 8 a.m. and ordered 
them back to work. 
 
A few hundred miles north of Oahu, the Japanese task force, bristling 
with guns , planes, and hate for Americans, bore down on the Pacific 
Fleet. A few hours earlier, a message had arrived from Tokyo that caused 
Commander Mitsuo Fuchida, the pilot who was to head the first wave of 
the air attack, to breathe a sigh of relief. It had been relayed from 
Yoshikawa, and it reported that no barrage balloons had yet been 
emplaced to protect the fleet from air attack. The same message also 
caused Commander Minoru Genda to sigh with relief. It stated that the 
battleships appeared not to be protected by torpedo nets . Genda had 
conceived the plan of shallow-water torpedo attack on the anchored 
American ships. 
A little more than an hour after the hands of Honolulu clocks had 
snipped off December 6 and opened out into the first hours of December 
7, the Pearl Harbor strike force received Tokyo's relay of Yoshikawa's 
final message. The American ships were still in harbor, awaiting the ax 
stroke with fat complacency. They were apparently not even protected by 
air search. Was it all a decoy? The strike force's radio officer, Commander 
Kanjiro Ono, listened intently to Honolulu's radio station KGMB for any 
inkling that the Americans knew of them. He heard only the soft  
melodies of the islands. On Hiryu, the flight deck officer slipped bits of 
paper between each plane 's radio transmitter key and its contact point to 
make sure that radio silence, so carefully preserved for almost two 
weeks, would not be accidentally broken in the last few hours to destroy 
the element of surprise. 
 
As Yoshikawa's final report was being decoded aboard Akagi, Kramer 
returned to the Navy Department he had left only seven hours before, 
and began working again. It was 7:30 on the morning of Sunday, 
December 7. 
Brotherhood's decryptment of the 14th part was on his desk when he 
arrived. It took him about half an hour to ready a smooth version, and at 
8 o'clock he delivered the neatly typed copy to McCollum. Other copies 
went to S.I.S. for its distribution. Kramer then worked on other traffic in 
his office, interrupting himself only once, at 8:45, to bring a copy of the 
14th part to naval intelligence chief Wilkinson on his arrival at the Navy 
Department. At 9:30 he set out to deliver the full 14 parts to the meeting 
of the three secretaries. He stopped at the office of the Chief of Naval 
Operations to make sure that Stark had been given the message, which 
he had, and then walked and trotted to the White House. He got there at 
about 9:45 and gave the MAGIC pouch to Beardall, who had assigned 
himself to duty that morning because he thought the 14th part of the 
message that be had seen at Wilkinson's house the night before might be 
coming in. 
Beardall brought the folder to the President, who was 
in his bedroom. Roosevelt said good morning to him, read the 
intercept, and commented that it looked like the Japanese were going to 
break off negotiations. Then he returned the MAGIC, and Beardall took it 
back to the Navy Department. 
Kramer, meanwhile, had hurried across the west lawn of the White 
House to the ugly , ornate State Department building, arriving at about 
ten minutes of 10. The Army courier appeared at almost the same 
moment with the MAGIC for Hull and Stimson. Three State Department 
officials who saw MAGIC—Hornbeck, Ballantine, and Hamilton —were 
shown the 14th part by Hull's aide, John Stone , and the group discussed 
the situation in general terms until the secretaries arrived a few minutes 
later. Kramer gave his pouch to Knox and headed back to the Navy 
Department. 
Meanwhile, the translation of the one o'clock message had come up 
from S.I.S. It was placed in Bratton's hands about 9 a.m. while he was 
reading the 14th part. It "immediately stunned me into frenzied activity 
because of its implications, and from that time on I was busily engaged 
trying to locate various officers of the general staff and conferring with 
them on the exclusive subject of this message and its meaning," he said 
later. He tried first to get in touch with Marshall, calling him at his 
quarters at Fort Myer, and was told by an orderly that the chief of staff 
had gone on his customary Sunday morning horseback ride . Bratton 
directed the orderly: 
"Please go out at once, get assistance if necessary, and find General 
Marshall, ask him to—tell him who I am and tell him to go to the nearest 
telephone, that it is vitally important that I communicate with him at the 
earliest practicable moment." The orderly said he would. Bratton called 
Miles, told him of the message, and urged him to come down to the office 
at once. Between 10 and 10:30, Marshall called Bratton back. The 
colonel offered to drive out at once with the one o'clock message, but 
Marshall told him not to bother, that he was coming down to his office at 
once. Bratton obeyed. 
Kramer arrived back in GZ at about 10:20, and found there the one 
o'clock message. It struck him as forcibly as it had Bratton. He at once 
had Yeoman Bryant prepare a new set of folders for immediate delivery of 
the intercept. Included in the new set were other messages which 
S.I.S. had decrypted, and on which Kramer had been working earlier 
in the morning: Tokyo serial No. 904, which directed the ambassadors 
not to use an ordinary clerk in preparing the 14-part ultimatum for 
presentation to the Secretary of State, so as to preserve maximum  
security; serial No. 909, thanking the two ambassadors for all their 
efforts; and serial No. 910, ordering destruction of the remaining cipher 
machine and all machine codes. 
Kramer was about to dart out again when Pering, the GY watch officer, 
brought in a message in plain-language Japanese, ending with the 
telltale STOP that indicated it was an INGO DENPO message: KOYANAGI 
RIJIYORI SEIRINOTUGOO 
ARUNITVKI HATTORI MINAMI KINEBUNKO SETURITU KIKINO 
KYOKAINGAKU SKYUU DENPOO ARITASI STOP TOGO. Kramer 
recognized KOYANAGI as the codeword for England, and HATTORI as a 
codeword whose meaning he did not recall. He consulted his code list 
and saw that it meant Relations between Japan and {name of country) are 
not in accordance with expectation. But in his haste he overlooked that 
the common Japanese word minami, which means "south," had an INGO 
DENPO meaning of U.S.A. He interpreted the message as "Please have 
director Koyagani send a wire stating the sum which has been decided to 
be spent on the South Hattori Memorial Library in order that this 
business may be wound up." Consequently, he dictated a decode that 
omitted United States: Relations between Japan and England are not in 
accordance with expectation. Yeoman Bryant inserted this and three 
other minor messages that had come over from the Army into the folders. 
Kramer meanwhile made a navigator's time circle that indicated that one 
o'clock in Washington was dawn in Hawaii and the very early hours of 
the morning in the Far East around Singapore and the Philippines, 
which everybody seemed to be watching. He shoved the folders into the 
briefcase and dashed out the door. 
He went first to Stark's office, where the officers were discussing the 
14th part, summoned McCollum, gave him the pouch that included the 
final code-destruction and one o'clock messages, and mentioned to him 
the significance of the latter's timing. McCollum grasped it at once and 
disappeared into Stark's office. Kramer wheeled and hurried down the 
passageway. He emerged from the Navy Department building and turned 
right on Constitution 
Avenue, heading for the meeting in the State Department three or four 
blocks away. The urgency of the situation washed over him again, and he 
began to move on the double. 
He half trotted, half walked to State, getting there at about 10:45. 
Hull, Knox, and Stimson were still meeting. Kramer saw them grouped 
around the conference table when the door to Hull's office was opened 
briefly . He gave the MAGIC messages to Stone, explaining to him how the 
one o'clock time of delivery of the ultimatum tied in with the movement of 
a big Japanese convoy down the coast of Indochina, and mentioning in 
passing that the time in Hawaii would be 7:30 a.m. The final code-
destruction message was self-explanatory. Kramer carried a MAGIC pouch 
to the White House, and then returned, perspiring, to the Navy 
Department, to busy himself with still more MAGIC. At about 12:30, he 
spotted the omission of United States from the INGO DENPO message. 
Because the one o'clock meeting was so close, he telephoned the 
recipients with the correction , a practice he had followed several times in 
the past, but reached only McCollum and Bratton. He told them that 
United States was to be inserted in file number 7148. The force of it had 
been considerably lessened by the one o'clock message, but Kramer, 
conscientious beyond the basic requirements of duty, nevertheless 
planned to send around a corrected version. 
Safford later estimated that OP-20-G handled three times as much 
material that weekend as on a normal one; the GY log shows at least 28 
messages in PURPLE alone handled that Sunday. And these messages 
were processed much more expeditiously than at any other time in the 
past, Kramer said. The cryptanalysts had done their duty, and had done 
it superbly. Events now passed out of their hands. 
 
In Tokyo, the President's message to the Emperor had finally been 
delivered to Grew after a delay of ten hours. The chief of the censorship 
office had ordered that all foreign cables be held up for five hours one 
day and ten hours the next. The order had been issued at the request of 
a lieutenant colonel on the general staff, who asked that this be done "as 
a precaution." The President's "triple priority" message arrived on one of 
the ten-hour days, was stalled for the required time, and was finally 
delivered at 10:30 p.m., Tokyo time. 
Grew immediately arranged for a meeting with Togo and, when the 
message had been decoded, drove to Togo's official residence at 12:15 
a.m. He requested—as is the right of all ambassadors—an audience with 
the head of state to present the message, then read it aloud to Togo and 
gave him a copy. Togo promised to present the matter to the Throne and, 
despite the lateness of the hour, telephoned the Lord Keeper of the Privy  
Seal for an audience. Ministers of state would be received at any hour, 
and the audience was arranged for 3 a.m. Togo began having the 
message translated. 
 
It was then about 5:30 a.m., December 7, in Hawaii. The Japanese 
task force was only 250 miles north of Pearl Harbor. More than 2,000 
Americans with less than three hours to live slept or played in blissful 
ignorance of that fact. The hands of clocks in the Foreign Office in Tokyo, 
in the code room at the Japanese embassy in Washington, in the War 
and Navy departments, in Pearl Harbor, circled around and around, but 
not so quickly as the spinning propellers of Nagumo's ships. At 5:30, two 
cruisers catapulted off a pair of scout planes to make sure the Americans 
were still there. 
 
The clerks at the embassy had straggled back to work between 9:30 
and 10. They began decoding the longer cables first, as experience had 
shown that these were usually the more important. At the same time, the 
embassy's first secretary, Katzuso Okumura, was typing up the first 13 
parts of the ultimatum. He had been chosen because the Foreign Office 
had forbidden the use of an ordinary typist in the interests of secrecy 
and he was the only senior official who could operate a typewriter at all 
decently. At about 11:30, code clerk Juichi Yoshida adjusted the 
Alphabetical Typewriter to the proper keys and typed out a short code 
message. To the consternation of the entire staff, it turned out to be an 
instruction to deliver the 14-part message to Secretary Hull at 1 p.m., 
Washington time. The 14th part had not even been decoded from the 
sheaf of incoming cables! And only one code machine was left to decipher 
all the messages! 
A few blocks away, General Marshall had just arrived at the War 
Department. On his desk was the MAGIC folder with the 14-part message 
on top and the one o'clock message under it. He began to read the 
ultimatum carefully, some parts several times. Bratton and Brigadier 
General Leonard T. Gerow, the war plans chief, tried to get him to look at 
the one o'clock message, but it is rather difficult for subordinates to 
interrupt a four- star general, and he finished the ultimatum before 
finding the time-of-delivery message. It struck him with the same sense 
of urgency that it had the others, and he picked up the telephone to call 
Stark to see if he wanted to join him in sending a warning message to 
American forces in the Pacific. 
At approximately the same time, Ambassador Nomura was calling 
Hull to request an appointment at 1 p.m. And 230 miles north of Hawaii, 
the first wave of Japanese planes was thundering off the flight decks of 
the carriers. 
Stark was at that moment discussing the significance of the one 
o'clock message with Captain R. E. Schuirman, Navy's liaison with State. 
He told Marshall that he felt that enough warnings had been sent and 
that more would just confuse the commanders. Marshall thereupon 
wrote out the dispatch he wanted sent: 
 
Japanese are presenting at one p.m. Eastern Standard Time 
today what amounts to an ultimatum also they are under orders to 
destroy their code machine immediately Stop Just what 
significance the hour set may have we do not know but be on alert 
accordingly Stop 
 
On his desk Marshall had a scrambler telephone with which he could 
have called Short in Hawaii. The scrambling apparatus stood in a room 
next to his office, thus obviating the possibility of tapping the 
conversation in unscrambled form, as was done in commercial cases. 
But Marshall knew that scramblers afforded protection merely against 
casual listeners; they could be penetrated by a determined eavesdropper 
with proper equipment. He had on several occasions warned the 
President about security on his transatlantic telephone conversations 
with Ambassador Bullitt in France and later with Churchill—a wise 
move, for, though he did not know it, the Nazis had already penetrated 
that scrambler. The Japanese had evidenced some interest in the San 
Francisco-Honolulu scrambler, and Marshall was acutely sensitive "that 
the Japanese would have grasped at most any straw" to suggest to the 
isola- 
tionists that the administration had committed an overt act that had 
forced the Japanese hand. Japanese interception of a scrambler warning 
might thus have sent the country to war divided . So Marshall shunned 
the scrambler telephone and relied on the slightly slower but much more 
secure method of enciphering a written message. 
As he was completing the message, Stark called him back. He had 
reconsidered and wanted Marshall to add the usual admonition to show 
the message to the naval opposites. Marshall added: "Inform naval 
authorities of this communication." Stark offered the Navy 
communication facilities, but Marshall said that the Army's could get the 
message out as quickly. 
Marshall gave the message to Bratton to take it to the War 
Department message center for transmission to the commanding 
generals in the Philippines, Hawaii, the Caribbean , and West Coast, after 
vetoing a suggestion that it be typed first. As Bratton was leaving, Gerow 
called out that if there was any question as to priority, to send it to the 
Philippines first. Bratton, greatly agitated, gave the message to Colonel 
Edward French in the message center and asked how long it would take 
to get it out. French told him that it would be encoded in three minutes, 
on the air in eight, and in the hands of the addressees in twenty. Bratton 
returned and reported to Marshall, who did not understand the 
explanation and sent him back for a clarification. He still was not sure 
and sent Bratton back a third time, after which he was finally satisfied 
with the answer. 
Meanwhile, French had had the message typed anyway and then 
ordered it encoded on a machine that was operated from a typewriter 
keyboard . During the few minutes that this took, he checked his 
Honolulu circuit, and found that since early morning interference had 
been so bad that the small 10- kilowatt War Department radio could not 
" bust " through it. He knew that R.C.A. in San Francisco had a 40-
kilowatt transmitter which would have no difficulty in getting through, 
and that Western Union in San Francisco had a tube running across the 
street from its office to this R.C.A. office. He had also learned on the 
previous day that R.C.A. was installing a teletype circuit from its office in 
Honolulu to Short's headquarters at Fort Shafter. French figured that 
this would therefore be his most expeditious route; after the message had 
been 
encoded, he personally carried it over to his bank of six Western 
Union teletypes and, at 12:01 p.m. December 7, sent it on its way. 
Western Union forwarded it at 12:17, and 46 minutes later it was 
received by R.C.A. in Honolulu. Local time was 7:33 a.m. The first wave 
of Japanese planes was then only 37 miles away—so close that the Army 
radar operators at Opana Point, who had tracked the flight for several 
hours and had been told to " Forget it" when they first reported it, were 
about to lose it in the dead zone of the nearby hills. But though the 
teletype connection for Fort Shatter had been completed the day before, 
it was not in operation pending tests on Monday. R.C.A. put Marshall's 
message in an envelope marked "Commanding General" for hand 
delivery. 
 
In Tokyo, Togo had been received by the Emperor. He read the text of 
Roosevelt's message, then a draft of the imperial reply that he and Tojo 
had prepared. It stated that the 14-part note was to be considered as 
Japan's response. Hirohito assented, and at 3:15 a.m. Togo withdrew 
from the Divine Presence. Deeply moved, he recalled, "I passed solemnly, 
guided by a Court official, down several hundred yards of corridors, 
stretching serene and tranquil. Emerging at the carriage entrance of the 
Sakashita Gate, I gazed up at the brightly shining stars , and felt bathed 
in a sacred spirit . Through the Palace plaza in utter silence, hearing no 
sound of the sleeping capital but only the crunching of the gravel 
beneath the wheels of my car, I pondered that in a few short hours would 
dawn one of the eventful days of the history of the world." Even as he 
pondered, Japanese planes were circling over Pearl Harbor. 
 
In stark contrast to the calm stillness of Tokyo was the hectic bustle 
of the Japanese embassy on Massachusetts Avenue. 
Soon after the one o'clock message had been decoded, Okumura 
finished typing the first 13 parts. But he decided that this rough draft 
did not suit the formality of a document to be delivered to the Secretary 
of State. He began retyping it from the very beginning, being assisted 
now by a junior interpreter, Enseki. His task was complicated by two 
messages sent up from the code room, one ordering the insertion of a 
sentence that had been accidentally 
dropped, one changing a word. This required the retyping of several 
pages, including one just completed with a great deal of trouble. At about 
12:30, the code room finally gave him the 14th part of the ultimatum, 
but Okumura was nowhere near finished with the first 13. Nomura kept 
poking his head in the door to hurry him on. A few minutes after one, 
when it was evident that the document would not be finished for some 
time, the Japanese called Hull to request a postponement to 1:45, saying 
that the document they wished to present was not yet ready. Hull 
acquiesced. 
At almost exactly the time that the call to Hull was being placed, 
Commander Fuchida and his flight of 51 dive bombers, 49 high-level 
bombers, 40 torpedo planes, and 43 fighters arrived over Pearl Harbor. 
He fired a "black dragon" from his signal pistol to indicate that the 
squadrons should deploy in the assault pattern for complete surprise. 
Nine minutes later, he wirelessed the message "To, to, to"—the first 
syllable of the Japanese word for "Charge!" and the signal to attack. As 
the planes moved into position for their runs, he felt so certain that he 
had achieved complete surprise that, at 7:53, two minutes before the 
first bomb even fell, he jubilantly radioed " TORA ! TORA! TORA!" (" Tiger ! Tiger! 
Tiger!")—the prearranged codeword that indicated surprise. On Akagi, 
Nagumo turned to a brother officer and grasped his hand in a long, silent 
handshake. At 7:55, the first bomb exploded at the foot of the seaplane 
ramp at the southern end of Ford Island in the middle of Pearl Harbor. 
Okumura was still typing. His fingers struggled with the keys as 
torpedoes capsized Oklahoma, as bombs sank West Virginia, as 1,000 
men died in the searing inferno of  Arizona . At 1:50 p.m. Washington 
time, 25 minutes after the attack had started, he reached the end of his 
typing marathon. The two ambassadors, who were waiting in the 
vestibule, started for the State Department as soon as it was handed to 
them. 
 
The Japanese envoys arrived at the Department at 2:05 and went to 
the diplomatic waiting room [Hull wrote]. At almost that moment the 
President telephoned me from the White House. His voice was steady but 
clipped. 
He said, "There's a report that the Japanese have attacked Pearl 
Harbor." 
"Has the report been confirmed?" I asked. 
He said, "No." 
While each of us indicated his belief that the report was probably 
true, I suggested that he have it confirmed, having in mind my 
appointment with the Japanese Ambassadors. . . . 
Nomura and Kurusu came into my office at 2:20. I received them 
coldly and did not ask them to sit down. 
Nomura diffidently said he had been instructed by his Government to 
deliver a document to me at one o'clock, but that difficulty in decoding 
the message had delayed him. He then handed me his Government's 
note. 
I asked him why he had specified one o'clock in his first request for an 
interview . 
He replied that he did not know, but that was his instruction. 
I made a pretense of glancing through the note. I knew its contents 
already but naturally could give no indication of this fact. 
After reading two or three pages, I asked Nomura whether he had 
presented the document under instructions from his Government. 
He replied that he had. 
When I finished skimming the pages, I turned to Nomura and put my 
eye on him. 
"I must say," I said, "that in all my conversations with you during the 
last nine months I have never uttered one worth of untruth. This is borne 
out absolutely by the record. In all my fifty years of public service I have 
never seen a document that was more crowded with infamous falsehoods 
and distortions— infamous falsehoods and distortions on a scale so huge 
that I never imagined until today that any Government on this planet  
was capable of uttering them." 
Nomura seemed about to say something. His face was impassive, but I 
felt he was under great emotional strain . I stopped him with a motion of 
my hand. I nodded toward the' door. The Ambassadors turned without a 
word and walked out, their heads down. 
The warlords' hopes of shaving the warning time to the closest 
possible margin had quite literally gone up in the smoke of attack, and 
Japan had 'started hostilities without giving prior notification. Later, this 
failure to declare war would be made part of the charges on which the 
Japanese war criminals were tried—and convicted, some of them paying 
with their lives . Togo would try to exonerate himself by throwing the 
blame on the embassy personnel for neglecting to decipher the cables 
promptly and to type the ultimatum at once. Perhaps some lawyer 's 
talking point might have been salvaged if the ambassadors had grabbed 
Okumura's original copy, no matter how messy, and taken it to Hull at 1 
p.m., or if they had taken the first few pages of the fair copy at 1 p.m. 
and directed the embassy staff to rush the other pages over as 
completed. But even if the entire document had been delivered on time, 
the 25 minutes that remained until the attack would not have been 
sufficient time for all the steps needed to prevent surprise: reading the 
document, guessing that a military attack was intended, notifying the 
War and Navy departments, composing, enciphering, transmitting, and 
deciphering an appropriate warning, and alerting the outpost forces. This 
was just what the shoguns intended. But just as a multitude of human 
errors on the part of Americans, cascading one atop the other, helped 
make tactical surprise perfect , so a series of similar human errors on the 
part of the Japanese deprived them of their last vestige of legality. 
Shortly after the attack commenced, Tadao Fuchikama, a messenger 
for the Honolulu office of R.C.A., picked up a batch of cables for delivery. 
He knew that the war had started and that it was the Japanese who were 
attacking the ships in the harbor, but he felt he had his job to do 
anyway. He glanced at the addresses on the envelopes, including the one 
marked "Commanding General," and planned an efficient route. Shafter 
was well down the list. His motorcycle progressed slowly through the 
jammed traffic; once he was stopped by National Guardsmen who had 
almost taken him for a paratrooper. At 11:45, almost two hours after the 
last attackers had vanished, Marshall's warning message was delivered 
to the signal officer. It got to the decoding officer at 2:40 that afternoon 
and to Short himself at 3. He took one look at it and threw it into the 
wastebasket, saying that it wasn't of the slightest interest. 
In Tokyo, Grew was awakened at 7 a.m. by the tele- 
phone , summoning him to a meeting at 7:30 with Togo. On Grew's 
arrival, the Foreign Minister gave him the Emperor's reply to the 
President. He thanked Grew for his cooperation and saw him off at the 
door. Four hours had elapsed since the attack had begun, but Togo 
never mentioned it. Shortly thereafter, Grew learned of the outbreak of 
hostilities from an extra of the Yomiuri Shimbun hawked outside his 
window. The Japanese soon closed the embassy gates . 
The Japanese in Washington destroyed their last machine and codes 
after encoding a final message that they were so doing—the last message 
sent on the Washington-Tokyo circuit, and read, of course, by the 
American codebreakers. But in Honolulu, police guarding the consulate 
after the attack smelled papers burning and saw smoke coming from 
behind a door. Fearing a conflagration, they broke in and found the 
consulate staff burning its remaining documents in a washtub on the 
floor. The police confiscated what proved to be the telegraph file plus five 
burlap sacks full of torn papers. These reached Rochef ort's unit that 
evening. Woodward was still working long hours in an attempt to break 
the PA-K2 messages that Mayfield had brought. Since the attack, the fear 
of sabotage had swelled to enormous proportions. "Nothing coming to 
light," his notes read, "so it was decided to reverse the process of 
deciphering, allowing for the encoding party to have either purposely 
encrypted the messages in this manner or possibly to have made an error 
in using the system employed due to confusion. This netted results." 
At about 2 a.m. on December 9, he cracked one of the messages 
picked up in the consulate. It was one sent from the Foreign Ministry to 
Kita on the 6th: "Please wire immediately re the latter part of my #123 
any movements of the fleet after the 4th." With this, he was soon able to 
unlock the other PA-K2 messages—including the long one setting up 
Kühn's light-signaling system. At about the same time in OP-20-oz, 
Kramer, who had been too busy with the 13 parts on Saturday to work 
on this message, was breaking out charts of Oahu and Maui to help in 
de-garbling the message, which was finally reduced to plaintext by 
Thursday. Marshall later said that it was the first message that clearly 
indicated an attack on Pearl to him— but this was, of course, after the 
fact.  
 
From:   Tokyo 
To:        Washington 
7 December 1941 
#902           Part 14 of 14 
 
(Note: In the forwarding instructions to the radio station 
handling this part, appeared the plain English phrase 
“VERY IMPORTANT”) 
 
7. Obviously it is the intention of the American 
Government to conspire with Great Britain and other countries 
to obstruct Japan’s efforts toward the establishment of peace 
through the creation of a New Order in East Asia, and especially 
to preserve Anglo-American rights and interests by keeping Japan 
and China at war.  This intentiona has been revealed clearly 
during the course of the present negotiations.  Thus the earnest 
hope of the Japanese Government to adjust Japanese-American 
relations and to preserve and promote the peace of the Pacific 
through cooperation with the American Government has finally 
been lost. 
 
The Japanese Government regrets to have to notify hereby 
the American Government that in view of the attitude of the 
American Government it cannot but consider that it is impossible 
to reach an agreement through further negotiations. 
 
JD-1:7143         SECRET     (M)  Navy trans. 7 Dec 1941 (S-TT) 
 
The fourteenth part of the Japanese ultimatum, as distributed to MAGIC recipients 
 
The information from it was immediately passed to counterintelligence 
units in Hawaii, where invasion was thought highly probable. Their 
agents interrogated residents in the neighborhood of the houses  
mentioned in the dispatch and listened to recordings of KGMB want ads, 
but found that the signal system had never been used. They arrested 
Kühn, who confirmed this. He was convicted on espionage charges and 
imprisoned at Leavenworth Penitentiary until after the war, when he was 
paroled to leave the country. 
On December 7, while Honolulu was still reeling from the devastation 
of the attack, F.C.C. monitors there picked up a Japanese-language news 
broadcast from station jzi in Japan. The announcer boasted of a " death -
defying raid" at Pearl, reported other events, and, about halfway through 
the broadcast, declared: " Allow me to especially make a weather forecast 
at this time: west wind clear."  
 
-11- 
 
and China at war. This intention has been revealed clearly 
during the course of the present negotiation. Thus, the 
earnest hope of the Japanese Government to adjust Japanese-
American relations and to preserve and promote the peace of 
the Pacific through cooperation with the American 
Government has finally been lost. 
The Japanese Government regrets to have to notify hereby 
the American Government that in view of the attitude of the 
American Government it cannot but consider that it is 
impossible to reach an agreement through further 
negotiations* 
     December 7, 1941. 
 
The last page of the Japanese note as typed by First Secretary Katzuso Okwnura and 
handed to Secretary of State Cordell Hull while Pearl Harbor was being attacked 
 
The O.N.I. translator noted that "as far as I can recollect, no such 
Weather forecast has ever been made before" and that "it may be some 
sort of code." It was the long-awaited winds code execute, apparently 
sent indicating war with Britain to make sure that some Japanese 
outpost that had not reported destroying its codes by the codeword 
HARUNA Would burn them. 
Shortly after noon in Washington on the day after the attack, the 
President of the United States stood before a stormily applauding joint  
session of Congress and opened a black looseleaf notebook. When the 
cheers had subsided into a hushed solemnity, he began to speak : 
 
Yesterday, December 7, 1941—a date which will live in infamy—
the United States of America was suddenly and deliberately 
attacked by naval and air forces of the Empire of Japan. 
 
He alluded to the fatal Japanese delay in delivering the ultimatum: 
 
The United States was at peace with that nation and, at the 
solicitation of Japan, was still in conversation with its Government 
and its Emperor looking toward the maintenance of peace in the 
Pacific. In deed, one hour after Japanese air squadrons hac 
commenced bombing in Oahu, the Japanese Ambas sador to the 
United States and his colleague delivered to the Secretary of State 
a formal reply to a recen American message. While this reply stated 
that i seemed useless to continue the existing diplomats 
negotiations, it contained no threat or hint of war 01 armed attack. 
 
The war was on. The most treacherous onslaught it history had 
succeeded. Japan had cloaked the strike fores in absolute secrecy. She 
had dissembled with diplomatic conversations and with jabs toward the 
south. She had—ir a precaution whose wisdom she but dimly realized— 
swathed her plans in a communications security so all enveloping that 
not a whisper of them ever floated ont But if the cryptanalysts had no chance to warn of th American lives before the war, they foum ample opportunities to exert 
their subtle and pervasivr talents during the struggle. In the 1,350 days 
of conflici in which an angry America turned Japan's tactical victory at 
Pearl Harbor into total strategic defeat, the cryptanalysts, in the words of 
the Joint Congressional Committee, "contributed enormously to the 
defeat of the enemy, greatly shortened the war, and saved many 
thousands of lives." 
That, however, is another story. 
 
3.  The First 3,000 Years 
 
ON A DAY  nearly 4,000 years ago, in a town called Menet Khufu 
bordering the thin ribbon of the Nile, a master scribe sketched out the 
hieroglyphs that told the story of his lord's life—and in so doing he 
opened the recorded history of cryptology. His was not a system of secret 
writing as the modern 
world knows it; he used no fully developed code of hieroglyphic 
symbol substitutions. His inscription, carved about 1900 B.C. into the 
living rock in the main chamber of the tomb of the nobleman 
Khnumhotep II, merely uses some unusual hieroglyphic symbols here 
and there in place of the more ordinary ones. Most occur in the last 20 
columns of the inscription's 222, in a section recording the monuments 
that Khnumhotep had erected in the service of the pharaoh Amenemhet 
II. The intention was not to make it hard to read the text. It was to 
impart a dignity and authority to it, perhaps in the same way that a 
government proclamation will spell out "In the year of Our Lord One 
thousand eight hundred and sixty three" instead of just writing "1863." 
The anonymous scribe may also have been demonstrating his knowledge 
for posterity. Thus the inscription was not secret writing, but it 
incorporated one of the essential elements of cryptography: a deliberate 
transformation of the writing. It is the oldest text known to do so. 
As Egyptian civilization waxed, as the writing developed and the 
tombs of the venerated dead multiplied, these transformations grew more 
complicated, more contrived, and more common. Eventually the scribes 
were replacing the usual hieroglyphic form of a letter, like the full-face 
mouth representing /r/, by a different form, like a profiled mouth. 
Sometimes they used new hieroglyphs whose first sound represented the 
letter desired, as a picture of a pig, "rer," would mean /r/. Sometimes the 
sounds of the two hieroglyphs differed but their images resembled one 
another. The horned asp, representing HI, was replaced by the serpent , 
representing /z/. And sometimes the scribes used a hieroglyph on the 
rebus principle, as in English a picture of a bee might represent b; thus a 
sailboat, "khentey," stands for another Egyptian word khentey, which 
means "who presides at"—this latter being part of a title of the god Amon , 
"he who presides at Karnak." These procedures °f acrophony and the 
rebus are essentially those of ordinary Egyptian writing; it was through 
them that the hieroglyphics originally acquired their sound values. The 
Egyptian transformations merely carry them further, elaborate them, and 
make them more artificial . 
The transformations occur in funerary formulas, in a hymn to Thoth, 
in a chapter of the Book of the Dead, on the sarcophagus of the pharaoh 
Seti I, in royal titles dis- 
played in Luxor, on the architrave of the Temple of Luxor, on stele, in 
laudatory biographic inscriptions. There is nothing meant to be 
concealed in all this; indeed, many of the statements are repeated in 
ordinary form right next to the altered ones. Why, then, the 
transformations? Sometimes for essentially the same reason as in 
Khnumhotep's tomb: to impress the reader. Occasionally for a 
calligraphic or decorative effect; rarely, to indicate a contemporary 
pronunciation ; perhaps even for a deliberate archaism as a reaction 
against foreign influence. 
But many inscriptions are tinctured, for the first time, with the 
second essential for cryptology—secrecy. In a few cases, the secrecy was 
intended to increase the mystery and hence the arcane magical powers of 
certain religious texts. But the secrecy in many more cases resulted from 
the understandable desire of the Egyptians to have passersby read their 
epitaphs and so confer upon the departed the blessings written therein. 
In Egypt , with its concentration upon the afterlife, the number of these 
inscriptions soon • proliferated to such an extent that the attention and 
the goodwill of visitors flagged. To revive their interest, the scribes 
deliberately made the inscriptions a bit obscure . They introduced the 
cryptographic signs to catch the reader's eye, make him wonder, and 
tempt him into unriddling them — and so into reading the blessings. It 
was a sort of Madison Avenue technique in the Valley of the Kings . But 
the technique failed utterly. Instead of interesting the readers, it 
evidently destroyed even the slightest desire to read the epitaphs, for 
soon after the funerary cryptography was begun, it was abandoned. 
 
[Codebreakers 070.jpg]
 
The addition of secrecy to the transformations produced 
cryptography. True, it was more of a game than anything else—it sought 
to delay comprehension for only the shortest possible time, not the 
longest —and the cryptanalysis was, likewise, just a puzzle. Egypt's was 
thus a quasi cryptology in contrast to the deadly serious science of today. 
Yet great things have small beginnings, and these hieroglyphs did 
include, though in an imperfect fashion, the two elements of secrecy and 
transformation that comprise the essential attributes of the science. And 
so cryptology was born. 
 
In its first 3,000 years, it did not grow steadily. Cryptology arose  
independently in many places, and in most of them it died the deaths of 
its civilizations. In other places, it survived, embedded in a literature , 
and from this the next generation could climb to higher levels. But 
progress was slow and jerky . More was lost than retained. Much of the 
history of cryptology of this time is a patchwork, a crazy quilt of 
unrelated items, sprouting, flourishing, withering. Only toward the 
Western Renaissance does the accreting knowledge begin to build up a 
momentum . The story of cryptology during these years is, in other words, 
exactly the story of mankind. 
 
China, the only high civilization of antiquity to use ideographic 
writing, seems never to have developed much real cryptography—
perhaps for that reason. In one case known for military purposes, the 
11th -century compilation , Wu-ching tsung-yao ("Essentials from Military 
Classics"), recommended a true if small code. To a list of 40 plaintext 
items, ranging from requests for bows and arrows to the report of a 
victory, the correspondents would assign the first 40 ideograms of a 
poem . Then, when a lieutenant wished, for example, to request more 
arrows, he was to Write the corresponding ideogram at a specified place 
on an ordinary dispatch and stamp his seal on it. 
In China's great neighbor to the west, India, whose civilization 
likewise developed early and to high estate , several forms of secret 
communications were known and, aPparently, practiced. The Artha-
sastra, a classic work on statecraft attributed to Kautilya, in describing 
the espionage service of India as practically riddling the country with 
sPies, recommended that the officers of the institutes of £spionage give 
their spies their assignments by secret writ - 
ing. Perhaps most interesting to cryptologists, amateur or 
professional, is that Vatsyayana's famous textbook of erotics, the  Kama -
sutra,  lists secret writing as one of the 64 arts , or yogas, that women 
should know and practice. The fourth great civilization of antiquity, the 
Mesopo-tamian, rather paralleled Egypt early in its cryptographic 
evolution , but then surpassed it. Thus, in the last period of cuneiform 
writing, in colophons written at Uruk (in present-day Iraq ) under the 
Seleucid kings in the last few score years before the Christian era, 
occasional scribes converted their names into numbers. The 
encipherment—if such it be—may have been only for amusement or to 
show off. 
 
The Holy Scriptures themselves have not escaped a touch of 
cryptography—or protocryptography, to be precise, for the element of 
secrecy is lacking. 
Hebrew tradition offers at least two such conversions in the Old 
Testament (none are recorded for the New). In Jeremiah 25:26 and 51:41, 
the form SHESHACH appears in place of Babel ("Babylon"). The second 
occurrence strikingly demonstrates the lack of a secrecy motive, since 
the phrase with SHESHACH is immediately followed by one using 
"Babylon": 
How is Sheshach taken! And the praise of the whole earth seized! How 
is Babylon become an astonishment Among the nations! 
Confirmation that SHESHACH is really a substitute for Babel and not a 
wholly separate place comes from the Septuagint and the Targums, the 
Aramaic paraphrases of the Bible , which simply use "Babel" where the 
Old Testament version has SHESHACH. The second transformation, at 
Jeremiah 51:1, puts LEB KAMAI (" heart of my enemy") for Kashdim 
("Chaldeans"). 
Both transformations resulted from the application of a traditional  
substitution of letters called "atbash," in which the last letter of the 
Hebrew alphabet replaces the first, and vice versa; the next-to-last 
replaces the second, and vice versa; and so on. It is the Hebrew 
equivalent of a = z, b — Y, c = x,. . . , z = A. 
 
[Codebreakers 073.jpg] 
 
Consequently, in Babel, the repeated b, or  beth , the second letter of the 
Hebrew alphabet, became the repeated SH, or  SHIN , the next-to-last letter, 
in SHESHACH.  Similarly , the /, or lamed, became the hard CH, or KAPH. The 
kaph of Kashdim reciprocally became the LAMED of LEB KAMAI. In this 
determination, the Hebrew letters sin and shin, which differ only by 
where a dot is placed, are regarded as the same letter. The only letters in 
Hebrew are consonants and two silent letters, aleph and ayin; vowels are 
represented by dots or lines, usually below the letters. What is a final i in 
the English LEB KAMAI is a letter YOD in Hebrew, whose atbash reciprocal 
is mem. The word "atbash," incidentally, derives from the very procedure 
it denotes, since it is composed of aleph, taw, beth, and shin—the first, 
last, second, and next-to-last letters of the Hebrew alphabet. 
Both SHESHACH and LEB KAMAI have considerably embarrassed biblical 
commentators. They have devised numerous ingenious explanations for 
why so odd a result as LEB KAMAI would be desired, or why secrecy was 
wanted. Some have even thought Sheshach the name of a Babylonian 
district. But the idea of simple scribal manipulation, which would mean 
that such desires never even existed, and which is advanced by modern 
authorities and bolstered by the similar examples from other cultures  
and by the predilection of scribes for amusing themselves with word and 
alphabet games , seems the best explanation. 
 
" Queen Anteia, Proetus's wife, had fallen in love with the handsome  
youth ," the "incomparable Bellerophon . . . who was endowed with every 
manly grace , and begged him to satisfy her passion in secret." So Homer  
begins the story in the  Iliad  that includes the world's first conscious  
reference to—as distinct from use of—secret writing. 
"But Bellerophon was a man of sound principles and refused. So 
Anteia went to King Proetus with a lying tale . 'Proetus,' she said, 
'Bellerophon has tried to ravish me. Kill him—or die yourself.' The king 
was enraged when he 
heard this infamous tale. He stopped short of putting Bellerophon to 
death—it was a thing he dared not do—but he packed him off to Lycia 
with sinister credentials from himself. He gave him a folded tablet on 
which he- had traced a number of devices with a deadly meaning, and 
told him to hand this to his father -in-law, the Lycian king, and thus 
ensure his own death." 
The Lycian king feasted Bellerophon for nine days. "But the tenth day 
came, and then, in the first rosy light of Dawn, he examined him and 
asked to see what credentials he had brought him from his son-in-law 
Proetus. When he had deciphered the fatal message from his son-in-law, 
the king's first step was to order Bellerophon to kill the Chimera," a fire -
breathing monster with a lion's head, a goat's body , and a serpent's tail. 
Bellerophon did. The Lycian king then tried one ruse after another to 
carry out the surreptitious instructions, but Bellerophon successively 
battled the Solymi, defeated the Amazons, and slew the best warriors of 
Lycia, who had ambushed him. In the end the Lycian king relented, 
realizing that the youth stood under the divine protection of the gods, 
and gave him his daughter and half his kingdom. 
This is the only mention of writing in the Iliad. Homer's language is 
not precise enough to tell exactly what the markings on the tablets were. 
They were probably nothing more than ordinary letters—actually 
substitution of symbols for letters seems too sophisticated for the era of 
the Trojan War. But the mystery that Homer throws around the tablets 
does suggest that some rudimentary form of concealment was used, 
perhaps some such allusion as "Treat this man as well as you did 
Glaucus," naming someone whom the king had had assassinated. The 
whole tone of the reference makes it fairly certain that here, in the first 
great literary work of European culture, appear that culture's first f aint 
glimmerings of secrecy in communication. 
A few centuries later, those glimmerings had become definite beams of 
light. Several stories in the Histories of Herodotus deal specifically with 
methods of steganography (not cryptography). The Father of History tells 
how one of the most important messages in the history of Western 
civilization was transmitted secretly. It gave to the Greeks the crucial 
information that Persia was planning to conquer them. According to 
Herodotus, 
 
The way they received the news was very remark - bale . 
Demaratus, the son of Ariston, who was an exile in Persia, was 
not, I imagine —and as is only natural to suppose —well disposed  
toward the Spartans; so it is open to question whether what he did 
was inspired by benevolence or malicious pleasure . Anyway,  as 
soon as news reached him at Susa that Xerxes had decided upon 
the invasion of Greece , he felt that he must pass on the 
information to Sparta . As the danger of discovery was great, there 
was only one way in which he could contrive to get the message 
through: this was by scraping the wax off a pair of wooden folding 
tablets, writing on the wood underneath what Xerxes intended to 
do, and then covering the message over with wax again. In this way 
the tablets, being apparently blank, would cause no trouble with 
the guards along the road . When the message reached its 
destination, no one was able to guess the secret until, as I 
understand, Cleomenes' daughter Gorgo , who was the wife of 
Leonidas, discovered it and told the others that, if they scraped the 
wax off, they would find something written on the wood 
underneath. This was done; the message was revealed and read, 
and afterwards passed on to the other Greeks. 
 
The rest is well-known. Thermopylae, Salamis, and Plataea ended the 
danger that the flame of Western civilization would be extinguished by an 
Oriental invasion. The story is not without a certain bitter irony, 
however, for Gorgo, who may be considered the first woman cryptanalyst, 
in a way pronounced a death sentence on her own husband : Leonidas 
died at the head of the heroic band of Spartans who held off the Persians 
for three crucial days at the narrow pass of Thermopylae. 
It was the Spartans, the most warlike of the Greeks, who established 
the first system of military cryptography. As early as the fifth century 
B.C., they employed a device called the "skytale," the earliest apparatus 
used in cryptology and one of the few ever devised in the whole history of 
the science for transposition ciphers. The skytale consists of a staff of 
wood around which a strip of papyrus or leather or parchment is 
wrapped close-packed. The secret message is written on the parchment 
down the length of the staff; the parchment is then unwound and sent on 
its way. The dis- 
connected letters make no sense unless the parchment is rewrapped 
around a baton of the same thickness as the first; then words leap from 
loop to loop, forming the message. 
Thucydides tells how it enciphered a message from the ephors, or 
rulers, of Sparta, ordering the too-ambitious Spartan prince and general 
Pausanius to follow the herald back home from where he was trying to 
ally himself with the Persians, or have war declared against him by the 
Spartans. He went. That was about 475 B.C. About a century later, 
according to Plutarch, another skytale message recalled another Spartan 
general, Lysander, to face charges of insubordination. 
Another Greek writer , Polybius , devised a system of signaling that has 
been adopted very widely as a cryptographic method. He arranged the 
letters in a square and numbered the rows and columns. To use the 
English alphabet, and merging / and /' in a single cell to fit the alphabet 
into a 5 X 5 square: 
 
  1 2  3 4 5 
1 a b  c  d e 
2 f  g  h ij k 
3 l  m n o p 
4 q r  s  t  u 
5 v w x y z 
 
Each letter may now be represented by two numbers—that of its row and 
that of its column. Thus e = 15, v = 51. Polybius suggested that these 
numbers be transmitted by means of torches—one torch in the right 
hand and five in the left standing for e, for example. This method could 
signal messages over long distances. But modern cryptographers have 
found several characteristics of the Polybius square, or "checkerboard," 
as it is now commonly called, exceedingly valuable—namely, the 
conversion of letters to numbers, the reduction in the number of different 
characters, and the division of a unit into two separately manipulable 
parts. Polybius' checkerboard has therefore become very widely used as 
the basis of a number of systems of encipherment. 
Polybius and others never said whether any of the substitution 
ciphers they described were actually used, and so the first attested use of 
that genre in political affairs come 
j>v\j\j   j A^r 
from the Romans — and from the greatest Roman of them all. Julius 
Caesar thus impressed his name permanently into cryptology. 
Suetonius , the gossip columnist of ancient Rome, says that Caesar 
wrote to Cicero and other friends in a cipher in which the plaintext 
letters were replaced by letters standing three places further down the 
alphabet, D for a, E for b, etc. Thus, the message  Omnia   Gallia  est divisa 
in partes tres would be enciphered (using the modern 26-letter alphabet) 
to RPQLD JDOOLD HVW GLYLVD LQ SDUWHV WUHV. To this day, any 
cipher alphabet that consists of the standard sequence, like Caesar's: 
 
Plain 
a b c d e f g h I j k l m 
Cipher  D E F G H I J K L M N O P 
Plain 
n o p q r s t u v w x y z 
Cipher  Q R S T U V W X Y Z A B O 
 
is called a Caesar alphabet, even if it begins with a letter other than D. 
It must be that as soon as a culture has reached a certain level, 
probably measured largely by its literacy , cryptography appears 
spontaneously — as its parents, language and writing, probably also did. 
The multiple human needs and desires that demand privacy among two 
or more people in the midst of social life must inevitably lead to 
cryptology wherever men thrive and wherever they write. Cultural  
diffusion seems a less likely explanation for its occurrence in. so many 
areas, many of them distant and isolated. 
The Yezidis, an obscure sect of about 25,000 people in, northern Iraq, 
use a cryptic script in their holy books because they fear persecution by 
their Moslem neighbors. Tibetans use a kind of cipher called "rin-spuns" 
for official correspondence; it is named for its inventor Rin-c'(hhen-) 
spuns(-pa), who lived in the 1300s. The Nsibidi secret society of Nigeria 
keeps its pictographic script from Europeans as much as possible 
because it is used chiefly to express love in rather direct imagery, and 
samples appear to be at least as pornographic as they are cryptographic. 
The cryptography of Thailand developed under Indian influence. An 
embryonic study of the subject even appears in a grammatical work 
entitled Poranavakya by Hluang Prasot Aksaraniti (Phe). One system, 
called "the erring Siamese," substitutes one delicate Siamese letter for 
another. In an- 
other system, consonants are divided into seven groups of five letters; 
a letter is indicated by writing the Siamese number of its group and 
placing vertical dots under it equal in number to the letter's place in its 
group. A system called "the hermit metamorphosing letters" writes the 
text backwards. 
 
[Codebreakers 078.jpg]
 
In the Europe of the Latin alphabet—from which modern cryptology 
would spring—cryptography flickered weakly. With the collapse of the 
Roman empire, Europe had plunged into the obscurity of the Dark Ages . 
Literacy had all but disappeared. Arts and sciences were forgotten , and 
cryptography was not excepted. Only during the Middle Ages occasional 
manuscripts, with an infrequent signature or gloss or "deo gratias" that a 
bored monk put into cipher to amuse himself, fitfully illuminate the 
cryptologic darkness , and, like a single candle guttering in a great 
medieval hall, their feeble flarings only emphasize the gloom. 
The systems used were simple in the extreme. Phrases 
were written vertically or backwards; dots were substituted for vowels; 
foreign alphabets, as Greek, Hebrew, and Armenian , were used; each 
letter of the plaintext was replaced by the one that follows it; in the most 
advanced system, special signs substituted for letters. For almost a 
thousand years, from before 500 to 1400, the cryptology of Western 
civilization stagnated. 
 
During all these years, cryptology was acquiring a taint that lingers 
even today—the conviction in the minds of many people that cryptology 
is a black art, a form of occultism whose practitioner must, in William F. 
Friedman's apt phrase, "perforce commune daily with dark spirits to 
accomplish his feats of mental jiu- jitsu ." 
In part it is a kind of guilt by association. From the early days of its 
existence, cryptology had served to obscure critical portions of writings 
dealing with the potent subject of magic—divinations, spells, curses, 
whatever conferred supernatural powers on its sorcerers. Another 
important factor was the confusion of cryptology with the Jewish 
kabbalah. 
But, important as all these were, the view that cryptology is black 
magic in itself springs ultimately from a superficial resemblance between 
cryptology and divination. Extracting an intelligible message from 
ciphertext seemed to be exactly the same thing as obtaining knowledge 
by examining the flight of birds , the location of stars and planets, the 
length and intersections of lines in the hand, the entrails of sheep, the 
position of dregs in a teacup. In all of these, the wizard-like operator  
draws sense from grotesque, unfamiliar, and apparently meaningless 
signs. He makes known the unknown. 
All this stained cryptology so deeply with the dark hues of esoterism 
that some of them still persist, noticeably coloring the public image of 
cryptology. People still think cryptanalysis mysterious. Book dealers still 
list cryptology under "occult." And in 1940 the United States conferred 
upon its Japanese diplomatic cryptanalyses the codename MAGIC. 
 
In none of the secret writing thus far was there any sustained 
cryptanalysis. Occasional cases, yes. But of any science of cryptanalysis, 
there was nothing. Only cryptography existed. And therefore cryptology, 
which involves 
both cryptography and cryptanalysis, had not yet come into being so 
far as all these cultures—including the Western —were concerned. 
Cryptology was born among the Arabs. They were the first to discover 
and write down the methods of cryptanalysis. The people that exploded 
out of Arabia in the 600s and flamed over vast areas of the known world 
swiftly engendered one of the highest civilizations that history -had yet 
seen. Science flowered. Arab medicine and mathematics became the best 
in the world—from the latter, in fact, comes the word "cipher." Practical  
arts flourished. Administrative techniques developed. The exuberant 
creative energies of such a culture, excluded by its religion from painting 
or sculpture, and inspired by it to an explication of the Holy Koran , 
poured into literary pursuits. Storytelling , exemplified by Sheherazade's 
Thousand and One Nights, word-riddles, rebuses, puns, anagrams, and 
similar games abounded; grammar became a major study. And included 
was secret writing. 
The Arabic knowledge of cryptography was fully set forth in the 
section on cryptology in the Subh al-a 'sha, an enormous, 14-volume 
encyclopedia written to afford the secretary class a systematic survey of 
all the important branches of knowledge. It was completed in 1412 and 
succeeded in its task. Its author, who lived in Egypt, was Shihab al-DIn 
abu '!-'Abbas Ahmad ben 'Ali ben Ahmad 'Abd Allah al-Qalqashandi. The 
cryptologic section, "Concerning the concealment of secret messages 
within letters," has two parts, one dealing with symbolic actions and 
allusions, the other with invisible inks and cryptology. Qalqashandi 
attributed most of his information on cryptology to the writings of Taj ad-
Din 'All ibn ad-Duraihim ben Muhammad ath-Tha' alibi al-Mausill, who 
lived from 1312 to 1361 and held various teaching and official posts 
under the Mamelukes in Syria and Egypt. Except for a theological 
treatise , none of his writings is extant, but he is reported to have 
authored two works on cryptology. 
After explaining that one may write in an unknown language to obtain 
secrecy, Ibn ad-Duraihim, according to Qalqashandi, gave seven systems 
of ciphers. This list encompassed, for the first time in cryptography, both 
transposition and substitution ciphers. Moreover , one system is the first 
known cipher ever to provide more than one substitute for a plaintext 
letter. Remarkable and important 
as this is, however, it is overshadowed by what follows— the first 
exposition on cryptanalysis in history. 
It appeared in full maturity in Qalqashandi's paraphrase of Ibn ad-
Duraihim, but its beginnings are probably to be found in the intense and 
minute scrutiny of the Koran by whole schools of grammarians in Basra, 
Kufa, and Baghdad to elucidate its meanings. Among other studies, they 
counted the frequency of words to attempt a chronology for the chapters 
of the Koran, certain words being considered as having been used only in 
the later chapters. Lexicography advanced this. In making a dictionary, 
considerations of letter-frequency and of which letters go or do not go 
together virtually thrust themselves upon the lexicographer. For 
example, the Arabs recognized early that za' was the rarest letter in 
Arabic and, contrariwise, that the omnipresence of the definite article "al-
" made alif and lam the most common letters in normal style. 
The Ibn ad-Duraihim—Qalqashandi exposition begins at the 
beginning: the cryptanalyst must know the language in which the 
cryptogram is written. Because Arabic, "the noblest and most exalted of 
all languages ," is "the one most frequently resorted to" (in that part of the 
world), there follows an extensive discussion of its linguistic 
characteristics. Lists are given of letters that are never found together in 
one word, of letters that rarely come together in a word, of combinations 
of letters that are not possible ("Thus tha' may not precede shin."), and 
so on. Finally, the exposition gives a list of letters in order of "frequency 
of usage in Arabic in the light of what a perusal of the Noble Koran 
reveals." The writers even note that "In non-Koranic writings, the 
frequency may be different from this." Following which, Qalqashandi 
explains lucidly the principles of cryptanalysis and demonstrates with 
two examples. But this knowledge vanished in the Arab decline. 
The technique of cryptanalysis rests on two phenomena. One is that 
all letters are not used equally in any language. In other words, the first 
26 letters of say, the Gettysburg Address do not contain one a, one b, one 
c, so on. Rather, some letters occur more often than others. The second 
phenomenon is that the proportions in which the letters occur remain 
constant . If 1,000 letters of the Gettysburg Address are counted and 
compared with 1,000 letters of a military dispatch and 1,000 of a sports  
story, the counts will show that in all three texts certain letters—always 
the 
same letters—will appear frequently. Other Jetters will appear very 
rarely in all three texts, and some letters will appear occasionally. Since 
these texts are all English, e will be the most frequent letter. The vowels 
a, o, i, and the consonants t, n, r, s, and h will also be of high frequency, 
while /', k, q, x and z will be of low frequency. This constancy suggests 
that a frequency count of the next text will show the same letters with 
the same frequencies—everi if that text happens to be concealed by a 
cipher system. The cryptanalyst can utilize the known frequencies to 
dislodge the text from the cipher. 
In other words, given a monoalphabet substitution whose plaintext he 
knows to be in English, the cryptanalyst will count the number of letters 
in the ciphertext. If he finds that, say, L is the most frequent, he knows 
by the nature of the cipher that it must stand for the most frequent letter 
in the hidden plaintext. Since that is English, he can expect that that 
letter is e. Consequently, he can assume that L represents e. This is the 
basic process of cryptanalysis. 
The process of identification continues through other letters. Usually 
in English t is the second most frequent letter, and it might well 
represent the second most frequent ciphertext letter. But frequency 
characteristics are not limited to individual letters. They extend to letter 
combinations. Thus in English the vowels a, i, and o associate relatively 
seldom with one another. The cryptanalyst, examining his statistics and 
finding three high-frequency letters that avoid one another, could 
assume that they represent the vowels. Then, seeing a ciphertext letter 
that follows vowels four-fifths of the time and precedes them only one-
fifth, he could guess that that letter stands for n, which behaves in just 
that way. Again, to spot  h he can use the fact that the combinations th 
and he are among the most common while ht and eh are relatively rare . 
Then he exploits these identifications to make others by deciphering 
as much of the message as he can with his equivalents and then 
guessing what the missing letters might be. Suppose that he has 
recovered e, t, and h. Inserting these values at one point he finds the 
partial plaintext the?e. He can assume that the missing letter is probably 
r or s and can test these assumptions at other points in the cryptogram. 
The one that yields intelligible plaintext is the correct one. Thus he 
continues until the entire cryptogram is solved. 
Monoalphabetic substitution is today a trivial form of cipher. But the 
technique of its solution lies at the heart of the cryptanalysis of nearly all 
more sophisticated substitution ciphers. Their solution consists in large 
measure of breaking down the cipher until the method for solving 
monoalphabetic substitutions can be applied. That method is therefore of 
fundamental importance. 
 
4.  The Rise of the West 
 
MODERN WESTERN cryptology emerged directly from the flowering of 
modern diplomacy. The ambassadors' reports were sometimes opened 
and read, and, if necessary, crypt-analyzed. By the end of the century, 
cryptology had become important enough for most states to keep full-
time cipher secretaries occupied in making up new keys, enciphering and 
deciphering messages, and solving intercepted dispatches. Sometimes 
the cryptanalysts were separate from the cipher secretaries and were 
called in only when needed. Perhaps the most elaborate organization was 
Venice's. It fell under the immediate control of the Council of Ten, the 
powerful and mysterious body that ruled the republic largely through its 
efficient secret police. Venice owed her preeminence largely to Giovanni  
Soro, who was perhaps the West's first great cryptanalyst. Soro, 
appointed cipher secretary in 1506 , enjoyed remarkable success in 
solving the ciphers of numerous principalities. His solution of a dispatch 
of Mark Anthony Coloana, chief of the army of the Holy Roman Emperor 
Maximilian I, requesting 20,000 ducats or the presence of the emperor 
with the army, gave an insight into Colonna's problems. So great was 
Soro's fame that other courts sharpened their ciphers, and as early as 
1510 the papal curia was sending him ciphers that no one in Rome could 
solve. But Venice had no monopoly . 
 
In 1589, Henry of Navarre , who was destined to become the most 
popular king in the history of France (he coined the slogan "A chicken in 
every peasant's pot every Sunday"), ascended to the throne as Henry IV 
and found himself embroiled still more fiercely in his bitter contest 
with the Holy League, a Catholic faction that refused to concede that a 
Protestant could wear the crown. The League, headed by the Duke of 
Mayenne, held Paris and all the other large cities of France, and was 
receiving large transfusions of men and money from Philip of Spain . 
Henry was tightly hemmed in, and it was at this juncture that some 
correspondence between Philip and two of his liaison officers, 
Commander Juan de Moreo and Ambassador Manosse, fell into Henry's 
hands. 
It was in cipher, but he had in his government at the time one 
Francois Viete , the seigneur de la Bigotiere, a 49-year-old lawyer from 
Poitou who had risen to become counselor of the parlement, or court of 
justice, of Tours and a privy counselor to Henry. Viete had for years 
amused himself with mathematics as a hobby—"Never was a man more 
born for mathematics," said Tallement des Reaux. As the man who first 
used letters for quantities in algebra , giving that study its characteristic 
look, Viete is today remembered as the Father of Algebra. A year before, 
he had solved a Spanish dispatch addressed to Alessandro Farnese, the 
Duke of Parma , who headed the Spanish forces of the League. Henry 
turned the new intercepts over to him to see if Viete could repeat his 
success. 
He could and did. The plaintext of the long letter from Moreo, in 
particular, was filled with intimate details of the negotiations with 
Mayenne: ". . . Your Majesty having 66,000 men in those states [the 
Netherlands], it would be nothing to allot 6,000 to so pressing a need. 
Should your refusal become known, all will be lost. ... I said nothing 
about that to the Duke of Parma. . . . The Duke of Mayenne stated to me 
that it was his wish to become king; I could not hold back my surprise. . 
. ." The message was couched in a new nomenclator that Philip had 
specially given Moreo when he departed for France; it consisted of the 
usual alphabet with homophonic substitutions, plus a code list of 413 
terms represented by groups of two or three letters (LO = Spain; PUL = 
Navarre; POM = King of Spain) or of two numbers, either underlined (64 = 
confederation) or dotted (94 = Your Majesty). A line above a two-digit 
group indicated a null. 
Moreo's letter had been dated October 28, 1589, and despite Viete's 
experience and the quantity of text, it was not until March 15 of the 
following year that Viete was 
able to send Henry the completed solution, though he had previously 
submitted bits and pieces. What Viete did not know was that, 110 miles 
from Tours, Henry had defeated Mayenne's superior force at Ivry west of 
Paris the day before, making the solution somewhat academic. 
Any chagrin that Viete felt did not deter him from extending his 
cryptanalytic successes. As he wrote to Henry in the letter forwarding the 
Moreo solution: "And do not get anxious that this will be an occasion for 
your enemies to change their ciphers and to remain more covert. They 
have changed and rechanged them, and nevertheless have been and 
always will be discovered in their tricks." It was an accurate prediction, 
for Viete continued to read the enciphered messages of Spain and of 
other principalities as well. But his pride led him straight into a trap in 
which a shrewd diplomat drew confidential information from him as 
deftly as he elicited the secret meaning from elegant and mysterious 
symbols. Giovanni Mocenigo, the Venetian ambassador to France, said 
that he was talking one day with Viete at Tours: 
 
He [Viete] had just told me that a great number of letters in 
cipher of the king of Spain as well as of the [Holy Roman] Emperor 
and of other princes had been intercepted, which he had 
deciphered and interpreted. And as I showed a great deal of 
astonishment, he said to me: 
"I will give your government effective proofs of it." He 
immediately brought me a thick packet of letters from the said 
princes which he had deciphered, and added: 
"I want you also to know that I know and translate your cipher." 
"I will not believe it," I said, "unless I see it." And as I had three 
kinds of cipher—an ordinary which I used, a different one which I 
did not use, and a third, called dalle Caselle—he showed me that 
he knew the first. Then, to better probe so grave an affair, I said to 
him, 
"You undoubtedly know our dalle Caselle cipher?" "For that, 
you have to skip a lot," he replied, meaning that he only knew 
portions of it. I asked him to let me   see   some   of   our   
deciphered   letters,   and   he promised to let me, but since then 
he has not spoken 
further about it to me, and, having left, I have not seen him any 
more. 
 
Mocenigo was reporting to the Council of Ten, and it was after hearing 
his remarks that they so promptly replaced their existing keys. 
Meanwhile, Philip had learned, from his own interceptions of French 
letters, that Viete had broken a cipher that the Spanish—who apparently 
knew little about cryptanaly-sis—had thought unbreakable. It irritated 
him, and thinking that he would cause trouble for the French at no cost 
to himself, told the pope that Henry could have read his ciphers only by 
black magic. But the tactic boomeranged. The pope, cognizant of the 
ability of his own cryptologist, Giovanni Batista Argenti, and perhaps 
even aware that papal cryptanalysts had themselves solved one of 
Philip's ciphers 30 years before, did nothing about the Spaniard's 
complaint; all Philip got for his effort was the ridicule and derision of 
everyone who heard about it. 
At about the same time, England's first great cryptanalyst helped to 
execute a sentence of death on that most romantic and tragic of royal 
ladies , Mary, Queen of Scots . 
He was Thomas Phelippes. Son of London's collector of customs, he 
traveled widely in France in his mid-twenties. As early as 1538, while in 
Paris, he had begun cryptanalyzing messages for Sir Francis 
Walsingham, Queen Elizabeth 's Satanic-looking minister in charge of 
espionage. Back in England, Phelippes became one of Walsingham's 
most confidential assistants. He was an indefatigable worker , 
corresponding tirelessly in his calligraphic hand with Walsingham's 
numerous agents. His letters show a fair acquaintance with literary 
allusions and classical quotations, and he appears to have been able to 
solve ciphers in Latin, French, and Italian and, less proficiently, in 
Spanish. The only known physical description of him comes from the pen 
of Mary of Scots herself , who describes Phelippes, whose hair and beard  
were blond, as "of low stature, slender every way, eated in the face with 
small pocks, of short sight , thirty years of age by appearance." 
Mary's unflattering comments betrayed her suspicions about 
Phelippes—suspicions that were well founded. For Phelippes and his 
master, Walsingham, were casting a jaundiced eye on Mary for reasons 
that, in their turn, were 
equally well founded. Mary was the heir apparent to the throne of 
England. She was also nominally queen of Scotland , though she had 
been ejected in a tangled series of - events and had been prevented from 
returning by the opposition of the strong Protestant party there to her 
indiscretions. She was a remarkable woman: beautiful, possessed of 
great personal charm , commanding the loyalty of her subordinates, 
courageous, unshakably devoted to her religion, but also unwise, 
stubborn, and capricious. Various Catholic factions had schemed more 
than once to seat her on the throne of England and so restore the realm 
to the Church . The chief result had been to confine Mary to various 
castles in England and to alert Walsingham to seek an opportunity to 
extirpate once and for all this cancer that threatened to destroy his own 
queen, Elizabeth. 
The opportunity arose in 1586. A former page of Mary's, Anthony 
Babington, began organizing a plot to have courtiers assassinate 
Elizabeth, incite a general Catholic uprising in England, and crown Mary. 
A conspiracy that involved the overthrow of the government naturally 
had ramifications all over the country, and Babington also gained the 
support of Philip II, who promised to send an expedition to help, once 
Elizabeth was safely dead. But the plan depended ultimately on the 
acquiescence of Mary, and to obtain this Babington had to communicate 
with her. 
This was no easy task. Mary was then being held incommunicado 
under house arrest at the country estate of Chartley. But a handsome 
former seminarian named Gilbert Gifford, recruited by Babington as a 
messenger, discovered a way of smuggling Mary's letters into Chartley in 
a beer keg. It worked so well that the French ambassador gave Gifford all 
the correspondence that had been accumulating for Mary for the past 
two years. 
Much of it was enciphered. But this was only part of the care that 
Mary took to ensure the security of her communications. She insisted 
that important letters be written within her suite and read to her before 
they were enciphered. Dispatches had to be sealed in her presence. The 
actual encipherment was usually performed by Gilbert Curll, her trusted 
secretary, less often by Jacques Nau, another secretary. Mary not 
infrequently ordered changes in her nomenclators, which were much 
smaller and flimsier than the diplomatic ones. 
What neither Mary nor Babington knew was that, despite 
their elaborate precautions, their correspondence was being delivered 
to Walsingham and Phelippes as quickly as they wrote it. Gilbert Gifford 
was a double-agent, a ne'er-do-well who had offered his services to 
Walsingham. Walsingham, seeing an unparalleled opportunity to 
insinuate his antennae into Mary's circles, employed Gifford to turn over 
to him all Mary's letters, which he copied and then passed on. It included 
the two-year backlog entrusted to Gifford by the French ambassador, 
and the rapidly growing volume of traffic generated by Babington's 
festering plot. These enciphered missives were being solved by Phelippes 
almost as quickly as he got his hands on them. As the conspiracy 
reached a crescendo of preparation in the middle of July, he was 
sometimes reading two or more in a day: two letters from the queen bear  
notations "decifred 18 July 1586," two others are marked as deciphered 
July 21, and there are still other cipher letters in the same packet in the 
records that bear no notations. 
During these three months, Walsingham cannily made no arrests, but 
simply let the plot develop and the correspondence accumulate in the 
hope that Mary would incriminate herself. His expectations were fulfilled. 
Early in July, Babington specified the details of the plan in a letter to 
Mary, referring to the Spanish invasion, her own deliverance, and "the 
dispatch of the usurping competitor." Mary considered her reply for a 
week and, after composing it carefully, had Curll encipher it; she sent it 
off to Babington on July 17. It was to prove fatal, for in it Mary 
acknowledged "this enterprise" and advised Babington of ways "to bring 
it to good success." Phelippes, on solving it, immediately endorsed it with 
the gallows mark. 
But Walsingham still lacked the names of the six young courtiers who 
were to commit the actual assassination. So when the letter reached 
Babington, it bore a postscript that was not on it when it left Mary's 
hands; in it Babington was asked for "the names and qualities of the six 
gentlemen which are to accomplish the designment." Both the forgery 
and the encipherment in the correct key seem to be the work of 
Phelippes. 
It proved unnecessary. Babington needed to go abroad to organize the 
invasion; at Walsingham's suggestion, there was a mixup in the 
passports. Babington, suspecting nothing, boldly came to the minister 
for help in cutting the red tape.  
 
[Codebreakers 089.jpg]
 
While he was dining at the nearby tavern with one of Walsingham's 
men, a note came, calling for his arrest. He caught a glimpse of it and, 
saying he was going to pay the bar bill and leaving his cloak and sword  
on the back of his chair , he slipped out and escaped. The hue and cry set 
up by his pursuers panicked the six young men. They fled for their lives, 
but within a month both they and Babington were caught and 
condemned to death after a two-day trial . Before they were executed, the 
authorities prudently extracted from Babington the cipher alphabets he 
had used with Mary. 
These, and Mary's letters, served as thoroughly incriminatory 
evidence in the Star Chamber proceedings that convicted her of high 
treason. Mary received the announcement that Elizabeth had signed her 
death warrant with majestic tranquillity, and at eight on the morning of 
February 8, 1587 , after eloquently reiterating her innocence and praying  
aloud for her church, for Elizabeth, for her son, and for all her enemies, 
mounted the platform with solemn dignity, knelt, and received the 
axeman's three strokes with the courage that had marked every other 
action of her life. Thus did Mary, Queen of Scots, exit this transient life 
and enter the more enduring one of legend, as her motto had prophesied: 
"In my end is my beginning." There seems little doubt that she would 
have died before her time, the politics of the day being what they were. 
But there seems equally little doubt that cryptology hastened her 
unnatural end. 
 
5.   On The Origin  of a  Species 
 
" DATO  and I were strolling in the Supreme Pontiff's gardens at the Vatican  
and we went from topic to topic marveling at the ingenuity that men 
showed in various enterprises , till Dato gave expression to his warm  
admiration for those men who can exploit what are called 'ciphers.' " 
So wrote Leon Battista Alberti near the beginning of the succinct but 
suggestive work that earned him the title of Father of Western 
Cryptology. Alberti was the first of a group of writers who, element by 
element, developed a type of cipher to which most of today's systems of 
cryptography belong. The species is polyalphabetic substitution. 
It was the amateurs of cryptology who created the species. The 
professionals, who almost certainly surpassed them in cryptanalytic 
expertise, concentrated on the down-to-earth problems of the systems 
that were then in use but are now outdated. The amateurs, unfettered to 
these realities, soared into the empyrean of theory. There were four 
whose thought took wings : a famous architect, an intellectual cleric, an 
ecclesiastical courtier, and a natural scientist . 
The architect was Alberti, a man who, perhaps better than anyone 
except Leonardo da Vinci, epitomizes the Renaissance ideal of the 
universal man. Born in 1404, the illegitimate but favored son of a family 
of rich Florentine merchants, Alberti enjoyed extraordinary intellectual 
and athletic aptitudes. He painted, composed music, and was regarded 
as one of the best organists of his day. Writings poured from his pen. His 
De Re Aedificatoria, the first printed book on architecture, written while 
Gothic churches were still being built, helped shape the thoughts of 
those who built such utterly non-Gothic structures as St. Peter's Basilica 
in Rome. Jacob Burckhardt, author of the classic The Civilization of the 
Renaissaance in  Italy , singled out Alberti as one of the truly all-sided 
men who tower above their numerous many-sided contemporaries. And 
another great Renaissance scholar, John Symonds, declared that "He 
presents the spirit of the 15th century at its very best." 
Among his friends was the pontifical secretary, Leonardo Dato, one of 
the learned men of his age, who during that memorable stroll in the 
Vatican gardens brought the conversation around to cryptology. "You've 
always been interested in these secrets of nature," Dato said. "What do 
you think of these decipherers? Have you tried your hand at it, as much 
as you know how to?" 
Alberti smiled. He knew that Date's duties included ciphers (it was 
before the curia had a separate cipher secretary). "You're the head of the 
papel secretariat," he teased. "Could it be that you had to use these 
things a few times in matters of great importance to His Holiness?" 
"That's why I brought it up," Dato replied candidly. "And because of 
the post I have, I want to be able to do it myself without having to use 
outside interpreters. For when they bring me letters in cipher intercepted 
by spies, it's no joking matter. So please—if you've thought up any new 
ideas having to do with this business, tell me about them." So Alberti 
promised that he would do some work on it so that Dato would see that 
it was profitable to have asked him, and the result was the essay that he 
wrote in 1466 or early 1467, when he was 62 or 63. 
He implied that he thought up the idea of frequency analysis all by 
himself, but the conception that he set forth is far too matured for that. 
Nevertheless, his remarkably lucid Latin essay, totaling about 25 
manuscript pages, constitutes the West's oldest extant text on 
cryptanalysis. 
Only after he had explained how ciphers are solved did he proceed to 
ways of preventing solution. He capped his work with a cipher of his own 
invention that he called "worthy of kings" and, like all inventors, claimed 
was unbreakable. This was the cipher disk that founded poly -
alphabeticity. With this invention, the West, which up to this point had 
equaled but had never surpassed the East in cryptology, took the lead 
that it has never lost. 
"I make two circles out of copper plates . One, the larger, is called 
stationary, the smaller is called movable. The diameter of the stationary 
plant is one-ninth greater than that of the movable plate. I divide the 
circumference of each circle into 24 equal parts. These parts are called 
cells. In the various cells of the larger circle I write the capital letters, one 
at a time in red, in the usual order of the letters, A first, B second, c third, 
and then the rest, omitting H and K [and Y] because they are not 
necessary." This gave him 20 letters, since j, u, and w were not in his 
alphabet, and in the remaining four spaces he inscribed the numbers 1 
and 4 in black. (The red and black seem to signify only that Alberti liked 
colors.) In each of the 24 cells of the movable circle he inscribed "a small 
letter in black, and not in regular order like the stationary characters, 
but scattered at random .  
 
Codebreakers 092.jpg
 
Thus we may suppose the first of them to be a, the second g, the third 
q, and so on with the rest until the 24 cells of the circle are full; for there 
are 24 characters in the Latin alphabet, the last being et [probably 
meaning "&"]. After completing these arrangements we place the smaller 
circle upon the larger so that a needle driven through the centers of both 
may serve as the axis of both and the movable plate may be revolved 
around it." 
The two correspondents—who, Alberti carefully pointed out, must 
each have identical disks—agree upon an index letter in the movable 
disk, say k. Then, to encipher, the sender places this prearranged index 
letter against any letter of the outer disk. He informs his correspondent 
of this position of the disk by writing, as the first letter of the ciphertext, 
this letter of the outer ring. Alberti gave the example of k being placed 
against B. "From this as a starting point all the other characters of the 
message will acquire the force and sounds of the stationary characters 
above them."* So far nothing remarkable had happened. But in his next 
sentence Alberti placed cryptography's feet on the road to its modern 
complexity. "After writing three or four words, I shall change the position 
of the index in our formula by turning the circle, so that the index k may 
be, say, under D. So in my message I shall write a capital D, and from this 
point on [ciphertext] k will signify no longer B but D, and all the other 
stationary letters at the top will receive new meanings." 
There is the crucial point: "new meanings." Each new position of the 
inner disk brings different letters opposite one another in the inner and 
outer rings. Consequently, each shift means that plaintext letters would 
be replaced with different ciphertext equivalents. For example, the 
plaintext word NO might be enciphered to fc at one setting and to ze at 
another. Equally, at each shift a given cipher-text letter would stand for a 
different plaintext letter than it did at the previous setting. Thus, the fc 
that formerly represented NO might, at the new setting, stand for 
plaintext TU. This shift in both plain and cipher equivalents dif- 
*In Alberti's disk, the outer capital letters are the plaintext and the 
inner lower-case letters are the ciphertext. This contradicts the 
convention of this book, and is being used in the section on Alberti only 
to avoid altering his text. The difference is signalized by not using italic 
for the lower case. 
1 
ferentiates polyalphabetic from homophonic or polyphonic 
substitution. 
Each new setting of Alberti's disk brought into play a new cipher 
alphabet, in which both the plaintext and the ciphertext equivalents are 
changed in regard to one another. There are as many of these alphabets 
as there are positions of his disk, and this multiplicity means that Alberti 
here devised the first polyalphabetic cipher. 
This achievement—critical in the history of cryptology —Alberti then 
adorned by another remarkable invention: enciphered code. It was for 
this that he had put numbers in the outer ring. In a table he permuted 
the numbers 1 to 4 in two-, three-, and four-digit groups, from 11 to 
4444, and used these as 336 codegroups for a small code. "In this table, 
according to agreement, we shall enter in the various lines at the 
numbers whatever complete phrases we please, for example, 
corresponding to 12, 'We have made ready the ships which we promised 
and supplied them with troops and grain.' " These code values did not 
change, any more than the mixed alphabet of the disk did. But the digits 
resulting from an encoding were then enciphered with the disk just as if 
they were plaintext letters. In Alberti's words, "These numbers I then 
insert in my message according to the formula of the cipher, representing 
them by the letters that denote these numbers." These numbers thus 
changed their ciphertext equivalents as the disk turned. Hence 341, 
perhaps meaning "Pope," might become mrp at one position and fco at 
another. This constitutes an excellent form of enciphered code, and just 
how precocious Alberti was may be seen by the fact that the major 
powers of the earth did not begin to encipher their code messages until 
400 years later, near the end of the 19th century, and even then their 
systems were much simpler than this. 
Alberti's three remarkable firsts—the earliest Western exposition of 
cryptanalysis, the invention of polyalphabetie substitution, and the 
invention of enciphered code—make him the Father of Western 
Cryptology. But although his treatise was published in Italian in a 
collection of his works in 1568, and although his ideas were absorbed by 
papal cryptologists and perhaps influenced the science's development, 
they never had the dynamic impact that such prodigious 
accomplishments ought to have produced. Symonds' evaluation of his 
work in general may both explain why 
and summarize the modern view of his cryptological contributions: 
"This man of many-sided genius came into the world too soon for the 
perfect exercise of his singular faculties. Whether we regard him from the 
point of view of art, of science, or of literature, he occupies in each 
department the position of precursor, pioneer , and indicator. Always 
original and always fertile, he prophesied of lands he was not privileged 
to enter, leaving the memory of dim and varied greatness rather than any 
solid monument behind him." 
Polyalphabeticity took another step forward in 1518, with the 
appearance of the first printed book on cryptology, written by one of the 
most famous intellectuals of his day. This was Johannes Trithemius, a 
Benedictine monk whose dabbling in alchemy and other mystic powers 
made him one of the most revered figures in occult science, while his 
more solid scholarship won him the title of "Father of Bibiliography." In 
1518, a year and a half after his death, his Polygraphiae libri sex, loannis 
Trithemii abbatis Peapolitani, quondam Spanheimensis, ad Maximilianum 
Caesarem ("Six Books of Polygraphy, by Johannes Trithemius, Abbot at 
Wurzburg, formerly at Spanheim, for the Emperor Maximilian") was 
published. By far the bulk of the volume consists of the columns of 
words printed in large Gothic type that Trithemius used in his systems of 
cryptography. But in the work's Book V appears, for the first time, the 
square table, or tableau. This is the elemental form of polyalphabetic 
substitution, for it exhibits all at once all the cipher alphabets in a 
particular system. These are usually all the same sequence of letters, but 
shifted to different positions in relation to the plaintext alphabet, as in 
Alberti's disk the inner alphabet assumed different positions in regard to 
the outer alphabet. The tableau sets them out in orderly fashion—the 
alphabets of the successive positions laid out in rows one below the 
other, each alphabet shifted one place to the left of the one above. Each 
row thus offers a different set of cipher substitutes to the letters of the 
plaintext alphabet at the top. Since there can be only as many rows as 
there are letters in the alphabet, the tableau is square. 
The simplest tableau is one that uses the normal alphabet in various 
positions as the cipher alphabets. Each cipher alphabet produces, in 
other words, a Caesar substitution. 
This is precisely Trithemius' tableau, which he called his " tabula  
recta." Its first and last few lines were: 
 
abcdefghiklmnopqrstuxyzw  
bcdefghiklmnopqrstuxyzwa  
cdefghiklmnopqrstuxyzwab  
defghiklmnopqrstuxyzwabc  
efghiklmnopqrstuxyzwabcd 
........................ 
zwabcdefghiklmnopqrstuxy  
wabodefghiklmnopqrstuxyz  
 
Trithemius used this tableau for his polyalphabetic encipherment, and in 
the simplest manner possible. He enciphered the first letter with the first 
alphabet, the second with the second, and so on. (He gave no separate 
plaintext alphabet, but the normal alphabet at the top can serve.) Thus a 
plaintext beginning Hunc caveto virum . . . became HXPF GFBMCZ FUEiB. ... 
In this particular message, he switched to another alphabet after 24 
letters, but in another example he followed the more normal procedure of 
repeating the alphabets over and over again in groups of 24. 
The great advantage of this procedure over Alberti's is that a new 
alphabet is brought into play with each letter. Alberti shifted alphabets 
only after three or four words. Thus the ciphertext would mirror the 
obvious pattern of repeated letters of a word like  Papa  ("Pope"), or in 
English, attack, and the cryptanalyst could seize upon this reflection to 
break into the cryptogram. The letter-by-letter encipherment obliterates 
this clue. 
 
If the first two steps in polyalphabeticity were made by men who were 
giants in their time, the third was taken by a man who was so 
unexceptional that he left almost no traces. This is Giovan Batista 
Belaso; the sum total of knowledge about him consists of the facts that 
he came from Brescia of a noble family, served in the suite of one 
Cardinal Carpi, and, in 1553 , brought out a little booklet entitled La cifra 
del. Sig. Giovan Bastista Belaso. In this he proposed the use of a literal, 
easily remembered, and easily changed key—he called it a 
"countersign"—for a poly-alphabetic cipher. Wrote Belaso: "This 
countersign may consist of some words in Italian or Latin or any other 
language, and the words may be few or many as desired. Then we take 
the words we wish to write, and put them 
on paper, writing them not too close together. Then over each of the 
letters we place a letter of our countersign in this form. Suppose, for 
example, our countersign is the little versetto VIRTUTI OMNIA PARENT . 
And suppose we wish to write these words: Larmata Turchesca partira a 
cinque di Luglio. We shall put them on paper in this manner: 
 
VIRTUTI OMNIA PARENT VIRTUTI OMNIA PARENT VI  
larmata turch escapa rtiraac inque dilugl io" 
 
The keyletter that is paired with a given plaintext letter indicates the 
alphabet of the tableau that is to be used to encipher that plaintext 
letter. Thus, / is to be enciphered by the V alphabet, a by the I alphabet, 
and so on. The system permits great flexibility: no longer did all 
messages have to be enciphered with one of a relatively few standard 
sequences of alphabets, but different ambassadors could be given 
individual keys, and, if it were feared that a key had been stolen or 
solved, a new one could be substituted with the greatest of ease. Keys 
caught on at once, and the Belaso invention laid the foundation for 
today's exceedingly complex arrangements, in which not one but several 
keys are employed and are varied at odd intervals. Moreover, in 
combining the best of his two predecessors—the mixed alphabet of 
Alberti and the letter-by-letter encipherment of Trithemius—with his own 
brilliant idea of a literal key, he created the modern concept of 
polyalphabetic substitution. 
 
It is clear that a key that changes with each message provides more 
security than one that is used over and over for several messages. The 
ultimate , of course, is a key that changes with each message. Several 
men devised an exceedingly clever way to ensure this change: use the 
message itself as its own key. This is called an "autokey." 
The comedy of errors and neglect that constitutes so much of the 
historiography of cryptology reached a climax of irony when it came to 
the inventor of the first really acceptable autokey system. It ignored this 
important contribution and instead named a regressive and elementary  
cipher for him though he had nothing to do with it. And so strong is the 
grip of tradition that, despite modern scholarship, the name of Blaise de 
Vigenere remains firmly attached to what has become the archetypal 
system of 
polyalphabetic substitution and probably the most famous cipher 
system of all time. 
Vigenere was born in the village of Saint-Pourcain, about halfway 
between Paris and Marseilles, on April 5, 1523. At 24, he entered the 
service of the Duke of Nevers, to whose house he remained attached the 
rest of his life, except for periods at court and as a diplomat. In 1549, at 
26, he went to Rome on a two-year diplomatic mission. 
It was here that he was first thrown into contact with cryptology, and 
he seems to have steeped himself in it. He read the books of Trithemius, 
Belaso, and other writers, and the unpublished manuscript of Alberti. He 
evidently conversed with the experts of the papal curia, for he tells 
anecdotes that he could have heard only in the shoptalk of these 
cryptologists. At 47, Vigenere quit the court, turned over his annuity of 
1,000 livres a year to the poor of Paris, married the much younger Marie 
Vare, and devoted himself to his writing. His Traicte des Chiffres, which 
was written in 1585 despite the distraction of a year-old baby daughter, 
appeared, elegantly rubricated, in 1586, and was reprinted the following 
year. His autokey system used the plaintext as the key. It provided a 
priming key. This consisted of a single letter, known to both encipherer 
and decipherer, with which the decipherer could decipher the first 
cryptogram letter and so get a start on his, work. With this, he would get 
the first plaintext letter, then use this as the key to decipher the second 
cryptogram letter, use that plaintext as the key to decipher the third 
cryptogram letter, and so on. 
 
key      DA      UNO      MD      ELETERNE  
plain    au      nom      de      léternel  
cipher   XI      AHG      UP      TMLSHIXT  
 
The system works well and affords fair guarantees of security; it has 
been embodied in a number of modern cipher machines. 
In spite of Vigenere's clear exposition of his technique, it was entirely 
forgotten and only entered the stream of cryptology late in the 19th 
century after it had been reinvented. Writers on cryptology then added 
insult to injury by degrading Vigenere's system into one much more 
elementary. 
The cipher now universally called the Vigenere employs 
only standard alphabets and a short repeating keyword—a system far 
more susceptible to solution than Vigenere's autokey. Its tableau 
consists of a modern tabula recta: 26 standard horizontal alphabets, 
each slid one space to the left of the one above. These are the cipher 
alphabets. A normal alphabet for the plaintext stands at the top. Another 
normal alphabet, which merely repeats the initial letters of the horizontal 
ciphertext alphabets, runs down the left side. This is the key alphabet. 
Both correspondents must know the keyword. The encipherer repeats 
this above the plaintext letters until each one has a keyletter. He seeks 
the plaintext letter in the top alphabet and the keyletter in the side. Then 
he traces down from the top and in from the side. The ciphertext letter 
stands at the intersection of the column and the row. The encipherer 
repeats this process with all the letters of the plaintext. To decipher, the 
clerk begins with the keyletter, runs in along the ciphertext alphabet 
until he strikes the cipher letter, then follows the column of letters 
upward until he emerges at the plaintext letter at the top. For example: 
 
key          TYPETYPETYPET  
plain        nowisthetimef  
cipher       OMLMLRWIMGBIY  
key          YPETYPETYPET  
plain        orallgoodmen  
cipher       MGEEJVSHBBIG  
 
Polyalphabetic ciphers were, when used with mixed alphabets and 
without word divisions, unbreakable to the cryptanalysts of the 
Renaissance. Why, then, did the nomenclator reign supreme for 300 
years? Why did cryptographers not use the polyalphabetic system 
instead? 
Apparently because they disliked its slowness and distrusted its 
accuracy. Encipherment in a polyalphabetic system, with its need to 
keep track of which alphabet was in use at every point and to make sure 
that the ciphertext letter was taken from that alphabet, could not 
compare in speed with a nomenclator encipherment. The well-informed 
author of an anonymous 17th -century "Traitte de 1'art de deschiffrer" in 
the Royal Archives at Brussels stated that chancelleries do not use 
polyalphabetics because it takes too long to encipher them and because 
the dropping of a single ciphertext letter garbles the message from that 
point on. In 1819, William Blair , in a superb encyclopedia article 
  abcdefghiJklmnopqrstuvwxyz 
 
A ABCDEFGHIJKLMNOPQRSTUVWXYZ 
B BCDEFGHIJKLMNOPQRSTUVWXYZA 
C CDEFGHIJKLMNOPQRSTUVWXYZAB 
D DEFGHIJKLMNOPQRSTUVWXYZABC 
E EFGHIJKLMNOPQRSTUVWXYZABCD 
P FGHIJKLMNOPQRSTUVWXYZABCDE 
Q GHIJKLMNOPQRSTUVWXYZABCDEF 
H HIJKLMNOPQBSTUVWXYZABCDEFQ 
I IJKLMNOPQHSTUVWXYZABCDEFGH 
J JKLMNOPQBSTUVWXYZABCDEFGHI 
K KLMNOPQBSTUVWXYZABCDEFGHIJ 
L LMNOPQRSTUVWXYZABCDEFGHIJK 
M MNOPQRSTUVWXYZABCDEFGHIJKL 
N NOPQRSTTUVWXYZABCBEFGHIJKLM 
O OPQRSTUVWXYZABCDEFGHIJKLMN 
P PQBSTUVWXYZABCDEFGHIJKLMNO 
Q QRSTUVWXYZABCDEFGHIJKLMNOP 
R BSTUVWXYZABCDEFGHIJKLMNOPQ 
S STUVWXYZABCDEFGHIJKLMNOPQB 
T TUVWXYZABCDEFGHIJKILMNOPQK 
U UVWXYZABCDEFGHIJKLMNOPQRST 
V VWXYZABCDEFGHIJKLMNOPQRSTU 
W WXYZABCDEFGHIJKLMNOPQBSTUV 
X XYZABCDEFGHIJKLMNOPQRSTUVW 
Y YZABCDEFGHIJKLMNOPQBSTUVWX 
Z ZABCDEFGHIJKLMNOPQBSTUVWXY 
The modern Vigenere tableau 
on cryptology, likewise argued that polyalphabetic substitution 
" requires too much time" and that "by the least mistake in writing is so 
confounded , that the confederate with his key shall never set it in order 
again." 
One might think that cipher clerks might have corrected such garbles 
by trial and error, especially in those more leisurely days. But they were 
not cryptanalysts and may not have known, or have wanted to know, 
how to make the necessary trials. Serious garbles would thus render the 
dispatch unreadable until a courier went out and returned with a 
correction; thus the cipher would have prevented communication instead 
of safeguarding it. 
 
6.  The Era of the Black Chambers 
 
REALMONT was under siege . The royal army, under Henry II of Bourbon, 
Prince of Conde, had invested it at dawn Wednesday, April 19, 1628. But 
the Huguenots, inside the battlements of the little town in southern 
France, were putting up a stiff defense. They cannonaded Conde from a 
tower and contemptuously rejected his demands that they surrender, 
saying that they would die instead. Conde brought up five big cannon  
from Albi, a dozen miles away, and on Sunday ranged them in an 
ominous line facing Realmont. 
That same day his soldiers captured an inhabitant of the town who 
was trying to carry an enciphered message to Huguenot forces outside. 
None of Conde's men could unriddle it, but during the week the prince 
learned that it might be solved by the scion of a leading family of Albi 
who was known to have an interest in ciphers. 
Conde sent him the cryptogram. The young man solved it on the spot. 
It revealed that the Huguenots desperately needed munitions and that, if 
they were not supplied, they would have to yield. This was news indeed, 
for despite the destruction of a number of houses by the Catholic 
batteries, the town was continuing to resist stoutly with no sign of 
surrender. Conde returned the cryptogram to the inhabitants, and on 
Sunday, April 30, 1628, though its fortifications were still unbreached 
and its defenses still apparently adequate for a long siege, Realmont 
suddenly and unexpectedly capitulated. With this dramatic success 
began the career of the man who was to become France's first full-time 
cryptologist: the great Antoine Rossignol . 
When word of the incident reached Cardinal Richelieu , the astute and 
able Gray Eminence of France, he at once attached this useful talent to 
his suite. Rossignol proved his worth almost immediately. The Catholic 
armies under Richelieu surrounding the chief Huguenot bastion of La 
Rochelle intercepted some letters in cipher, which the young codebreaker 
of Albi read with ease. He told His Eminence that the starving citizens 
were eagerly awaiting 
help that the English had promised to send by sea. When the fleet 
arrived, the primed guardships and forts so intimidated it that it stood 
off the port's entrance and made no serious attempt to force a passage . A 
month later, the city capitulated in full sight of the English vessels—and 
the great French tradition of expertise in cryptology had been founded. 
Rossignol very quickly established himself in the royal service. By 
1630, his solutions had made him rich enough to build a small but 
elegant chateau at Juvisy, 12 miles south of Paris, later surrounding it 
with a charming informal garden designed by Le Notre, the gardener of 
Versailles. Here Louis XIII stopped to visit the young crypt-analyst in 
1634, 1635 and 1636 on his returns to Paris from Fontainebleau. 
In the swashbuckling court of that monarch , and then in the 
resplendent one of Louis XIV, Rossignol served with an extraordinary 
facility. The stronghold of Hesdin surrendered a week sooner than it 
otherwise would have because he solved an enciphered plea for help, and 
then composed a reply in the same cipher telling the townspeople how 
futile their hopes were. How many other towns he compelled to 
surrender, how many diplomatic coups he made possible, how many 
betrayals he uncovered among the great nobles in those days of shifting 
allegiances, he never discussed. This reticence caused some at the court 
to charge that he never actually solved a single cipher, and that the 
cardinal spread inflated rumors about his abilities to discourage would-
be conspirators. But in fact Richelieu was frequently telling his 
subordinates such things as, "It is necessary to make use, in my opinion, 
of the letters of the man who has been arrested by the civil authorities at 
Mezieres, that is to say, have them put into Rossignol's hands to see if 
there is something important in them." Or, eight years later, in 1642, 
writing to Messieurs de Noyers and de Chavigny: "I saw, in some 
extracts, that Rossignol sent me, a truce negotiation of the King of 
England with the Prince of Orange; I do not think that it can have any 
effect, but ... it is up to you, gentlemen, to keep your eyes peeled." 
Rossignol's work gave him access to some of the greatest secrets of 
the state and the court, and consequently made him a figure of some 
prominence in the glittering court of Louis XIV. He appears in some of 
the major memoirs 
of that period. Tallement des Reaux tells some unflattering stories 
about him and calls him "a poor species of man" in his Historiettes. But 
the Duke of Saint- Simon , whose Memoires are a monument of French 
literature, wrote that Rossignol was "the most skillful decipherer of 
Europe. . . . No cipher escaped him; there were many which he read right 
away. This gave him many intimacies with the king, and made him an 
important man." Rossignol also became the first person to have his 
biography written solely because of his cryptologic abilities. Charles 
Perrault, who is better known as the formulator of the Mother Goose 
tales , included a two-page sketch of Rossignol's life, complete with 
engraved portrait , in his "Illustrious Men Who Have Appeared in France 
During This Century," in the company of such as Richelieu. Mazarin 
regarded his good will as important enough to write a letter of regret in 
1658 for some injury done to Rossignol at Paris—and to follow it up two 
months later with a note to a court official pressing him to do justice to 
the cryptanalyst "for the insult and violence that has been done him." A 
more particular sign of importance appears in the largesse that the king 
showered upon him: 14,000 ecus in 1653, 150,000 livres in 1672, and 
an annuity, late in his life, of 12,000—to name just some of his 
payments .* 
As he grew old, Rossignol retired to his country home at Juvisy 
though he reportedly continued to perform his special magic to the end 
of his life. His last days were brightened by an unmistakable 
demonstration of royal esteem: the Sun King made a detour in a progress 
back to Fon-tainebleau to visit him at Juvisy—this in an age when 
courtiers vied for the privilege of removing the king's pajamas at grand  
and petit levees each morning! Rossignol died soon after, in December of 
1682, only a few days short of his 83rd birthday on January 1. 
* One story about Rossignol should be deflated, however. This is that 
his solutions were made "in a fashion so marvelous to his 
contemporaries that the device with which a lock is opened when the key 
has been lost is still called in French a rossignol." While the fact of the 
current usage is true, its implied origin is false. Unfortunately for so 
charming an etymology, this particular use of the term rossignol appears 
as criminal argot in police documents as early as 1406 —almost two 
centuries before the cryptologist was born. Since the word also means 
"nightingale," it may be possible that the thieves adopted it as slang for a 
picklock because its nighttime solos of clicks and rasps were music to 
their ears . 
He had been the cryptologist of France in that incomparable moment 
when Moliere was her dramatist, Pascal her philosopher, La Fontaine her 
fabulist, and the supreme autocrat of the world her monarch. Rossignol 
was, like them, a superlative practitioner of his art at the foremost court 
of Europe in the very splendor of its golden age. 
 
Black chambers were common during the 1700s, but that of Vienna —
the Geheime Kabinets-Kanzlei—was reputed to be the best in all Europe. 
It ran with almost unbelievable efficiency. The bags of mail for delivery 
that morning to the embassies in Vienna were brought to the black 
chamber each day at 7 a.m. There the letters were opened by melting 
their seals with a candle. The order of the letters in an envelope was 
noted and the letters given to a subdirector. He read them and ordered 
the important parts copied. All the employees could write rapidly, and 
some knew shorthand. Long letters were dictated to save time, 
sometimes using four stenographers to a single letter. If a letter was in a 
language that he did not know, the subdirector gave it to a cabinet 
employee familiar with it. Two translators were always on hand. All 
European languages could be read, and when a new one was needed, an 
official learned it. Armenian, for example, took one cabinet polyglot only 
a few months to learn, and he was paid the usual 500 florins for his new 
knowledge. After copying, the letters were replaced in their envelopes in 
their original order and the envelopes re-sealed, using forged seals to 
impress the original wax. The letters were returned to the post office by 
9:30 a.m. 
At 10 a.m., the mail that was passing through this crossroads of the 
continent arrived and was handled in the same way, though with less 
hurry because it was in transit . Usually it would be back in the post by 2 
p.m., though sometimes it was kept as late as 7 p.m. At 11 a.m., 
interceptions made by the police for purposes of political surveillance 
arrived. And at 4 p.m., the couriers brought the letters that the 
embassies were sending out that day. These were back in the stream of 
communications by 6:30 p.m. Copied material was handed to the 
director of the cabinet, who excerpted information of special interest and 
routed it to the proper agencies, as police, army, or railway 
administration, and sent the mass of diplomatic material 
to the court. All told, the ten-man cabinet handled an average of 
between 80 and 100 letters a day. 
Astonishingly, their nimble fingers hardly ever stuffed letters into the 
wrong packet, despite the speed with which they worked. In one of the 
few recorded blunders, an intercepted letter to the Duke of Modena was 
erroneously re-sealed with the closely similar signet of Parma. When the 
duke noticed the substitution, he sent it to Parma with the wry note, "Not 
just me—you too." Both states protested, but the Viennese greeted them 
with a blank stare, a shrug, and a bland profession of ignorance. Despite 
this, the 
j existence of the black chamber was well known to the various 
delegates to the Austrian court, and was even tacitly acknowledged by 
the Austrians. When the British 
'ambassador complained humorously that he was getting copies 
instead of his original correspondence, the chancellor replied coolly, 
"How clumsy these people are!" 
Enciphered correspondence was subjected to the usual cryptanalytic 
sweating process. The Viennese enjoyed remarkable success in this work. 
The French ambassador, who was apprised of its successes from papers 
sold him by a masked man on a bridge , remarked in astonishment that 
"our ciphers of 1200 [groups] hold out only a little while against the 
ability of the Austrian decipherers." He added that though he suggested 
new ways of ciphering and continual changes of ciphers, "I still find 
myself without secure means for the secrets I have to transmit to 
Constantinople, Stockholm , and St. Petersburg ." 
The Viennese owed at least some of their success to their progressive 
personnel policies. Except in emergencies, the cryptanalysts worked one 
week and took off one week— apparently to keep them from cracking 
under the intense mental strain of the work. Though the pay was not 
high, substantial bonuses were given for solutions. For example, bonuses 
totalling 3,730 florins were disbursed between March 1, 1780, and 
March 31, 1781, for the solution of 15 important keys. Perhaps the most 
important incentive was the prestige accorded to the cryptanalysts by 
direct royal recognition of their value . Karl VI personally handed the 
cryptanalysts their bonuses and thanked them for their work. Empress 
Maria Theresa conferred frequently with the officials of the black 
chamber about the cipher service and the cryptanalytic ability of other 
countries; that remarkable woman demonstrated her grasp of the 
principles 
1 
involved by inquiring whether any of her ambassadors had 
corresponded too much in a single nomenclator and ought to be given a 
new key. The cryptanalysts sometimes even got paid for not solving a 
cipher: if a key was stolen from an embassy, the codebreakers would get 
a kind of unemployment compensation because they had no opportunity 
to win their bonus. In 1833, for example, the cabinet got three fifths of 
the solution bonus when the key of the French envoy was stealthily 
removed, copied, and replaced in a cupboard in the bedroom of the 
secretary of the French legation within a single night. 
A good glimpse into the achievements of the Geheime Kabinets-
Kanzlei is afforded by the letters of one of its best directors, Baron Ignaz 
de Koch , who served from 1749 to 1763 with the cover-title of secretary 
to Maria Theresa. On September 4, 1751, he sent to the Austrian 
ambassador in France some cryptanalyzed correspondence which 
"makes one see more and more the main principles that direct the 
cabinet in France." Two weeks later, in referring to some other 
cryptanalyses, he wrote, "This is the eighteenth cipher that we have got 
through during the course of the year; ... we are regarded, unhappily, as 
being too able in this art, and this thought makes the courts that fear 
that we can engross their correspondence change their keys at every 
instant , so to speak, each time sending ones more difficult and more 
laborious to decipher." Among letters solved during its existence were 
those of Napoleon , Talleyrand , and a host of lesser diplomats. These 
solutions were often made the basis of Austrian strategy . 
 
England, too, had its black chamber. It began with the cryptanalytic 
endeavors of John Wallis, the greatest English mathematician before 
Newton . After his death, it descended through his grandson to reach, on 
May 14, 1716, Edward Willes, a 22-year-old minister at Oriel College, 
Oxford. 
Willes embarked at once upon a career unique in the annals of 
cryptology and the church. He not only managed to reconcile his 
religious calling with an activity once condemned by churchly 
authorities, but also went on to become the only man in history to use 
cryptanalytic talents to procure ecclesiastical rewards. Within two years, 
he had been named rector of Barton, Bedfordshire, for solving more than 
300 pages of cipher that exposed Sweden 's 
attempt to foment an uprising in England. He virtually guaranteed his 
future when he testified before the House of Lords in 1723 . Here, Francis 
Atterbury, Bishop of Rochester, was being tried by his peers for 
attempting to set a pretender on the English throne. 
The pretender's cause exhorted the allegiance of many in England, 
and the nation's attention focused on Atterbury's trial. Most of the facts 
about the alleged conspiracy had come from his intercepted 
correspondence, and the most inculpatory evidence had been extracted 
from the portions in cipher by Willes and by Anthony Corbiere, a former 
foreign service official in his mid-thirties who had also been appointed a 
Decypherer in 1719. The Lords "thought it proper to call the Decypherers 
before them, in order to their being satisfied of the Truth of the 
Decyphering." To demonstrate this, Willes and Corbiere deposed, 
 
That several Letters, written in this Cypher, had been 
decyphered by them separately, one being many Miles distant in 
the Country, and the other in Town; and yet their Decyphering 
agreed; 
That Facts, unknown to them and the Government at the Time 
of their Decyphering, had been verified in every Circumstance by 
subsequent Discoveries; as, 
particularly, that of H------'s Ship coming in Ballast 
to fetch O------- to England which had been so de-cyphered by 
them Two Months before the Government had the least Notice of 
Halstead's having left England; 
That a Supplement of this Cypher, having been found among 
Dennis  Kelly's Papers the latter End of July, agreed with the Key 
they had formed of that Cypher the April before; 
That the Decyphering of the Letters signed  Jones lllington and 
1378, being afterwards applied by them to others written in the 
same Cypher, did immediately make pertinent Sense, and such as 
had an evident Connexion and Coherence with the Parts of those 
Letters that were out of Cypher, though the Words in Cypher were 
repeated in different Paragraphs, and differently combined. 
 
The two Decypherers appeared before the Lords on several occasions 
to swear to their solutions. Attenbury twice 
objected and was twice overruled. But on May 7, as Willes was 
testifying to the cryptanalysis of the three most incriminatory letters of 
all, and the bishop felt the noose tightening around him, he persisted in 
questioning Willes on the validity of the reading though the House had 
supported Willes' refusal to answer. He raised such a commotion that he 
and his counsel were ordered to withdraw, and the Lords voted upon the 
proposition , "that it is the Opinion of this House that it is not consistent 
with the public Safety , to ask the Decypherers any Questions, which may 
tend to discover the Art or Mystery of Decyphering." It was resolved in 
the affirmative, the solutions were accepted, and Atterbury, largely on 
this evidence, was found guilty, deprived of office, and banished from the 
realm. 
Willes, on the other hand, became Canon of Westminster the next 
year. His salary more than doubled to £500. He succeeded to ever more 
important posts every four or six years thereafter, and finally, in 1742, 
when the oldest of his three sons , Edward, Jr., obtained a patent as a 
Decypherer, he was created Bishop of St. David's, being translated the 
next year to the more prestigious see of Bath and Wells . The bishop and 
his son shared the substantial salary of £1,000 a year. In 1752, he 
brought another son, William, into the business at an eventual £200, 
and six years later a third son, Francis, who for some reason served 
without pay. 
Bishop Willes died in 1773 and was buried in Westminster Abbey . His 
sons Edward, Jr., and Francis inherited a large share of his fortune and 
landed property and, living as wealthy squires at Barton and Hampstead, 
continued their cryptanalytic work. Their brother William had retired in 
1794, but his three sons, Edward, William, and Francis Willes joined the 
Decyphering Branch in the 1790s. 
Though the Willes family dominated the cryptanalytic branch, others 
worked in it. Corbiere was paid through such sinecures as his 
appointment as naval officer at Jamaica, though he never stirred from 
England, and as Commissioner of Wines Licenses, which sounds like the 
cushiest of posts. He rose to Under Secretary of the Post Office but 
continued his cryptanalytic work, which ended after 24 years only with 
his death in 1743, when he was receiving £800. The other cryptanalysts 
at various times were James Rivers , Frederick Ashfield, John Lampe , 
f       George Neubourg, John Bode, Jr., one Scholing, and a 
Boelstring. 
\           These men received their foreign interceptions from the 
:' Secret Office and their domestic ones from the Private - Office, both 
subdivisions of the Post Office. The Secret Office was quartered in three 
rooms adjoining the Foreign Office and entered privately from Abchurch 
Lane . Fire and candles burned constantly in one room; the staff lodged in 
the others. It included men who made their life's work the specialty of 
unsealing diplomatic packets with such, deftness that they could be 
resealed without evidence of tampering; one such opener was J. E. Bode, 
father of John Bode, Jr. He regularly spent three hours on the dispatches 
of the King of Prussia, opening them and then re-sealing them with 
special wax and carefully counterfeited seals. Perhaps surprisingly in a 
bastion of human rights, its interceptions enjoyed full legality. The 
statute of 1657 that established the postal service declared outright that 
the mails were the best means of discovering dangerous and wicked 
designs against the commonwealth . Leases of 1660 and 1663, confirmed 
by the Post Office Act of 1711 , permitted government officials to open 
mail under warrants that they themselves issued. They sidestepped this 
bothersome procedure by promulgating all-inclusive general warrants.* 
The Secret Office sent interceptions en clair to the king and those in 
cipher to the cryptanalysts. 
They were known collectively as the Decyphering Branch. Unlike the 
Secret Office, the branch had no specific location. Its tiny staff of experts 
worked largely at home, receiving their material by special messenger. 
Nor had it any formal organization, the senior Decypherer being merely 
first among equals. More secret than the Secret Office, the branch's 
funds came from secret-service money issued to the Secretary of the Post 
Office from Parliament's surplus revenue . Security was tight—in all of 
England probably only 30 people knew what diplomatic correspondence 
was being read at any given moment. Nevertheless, most men of affairs 
were aware of the practice of opening 
*This activity forms the legal precedent for the modern tapping of 
telephones, at least in Britain. Significantly, however, the source of the 
power to intercept communications has never been determined. The 
Crown simply exercised it and, despite occasional debate, has continued 
to do so, presumably with the tacit approval of the public as necessary 
for the safety of the state. 
private letters, and they often enciphered their correspondence or 
entrusted it to private messengers when secrecy was essential. 
After the Elector of Hanover succeeded to the English throne as 
George I in 1714, retaining the rule of the German state, the Decyphering 
Branch collaborated with the black chamber maintained at Nienburg by 
the Hanoverian government. Cryptanalysts Bode, Lampe, and Neubourg 
had even been imported from there—an ironic development in view of a 
refusal of Wallis to divulge his technique to Hanover a few years earlier. 
Mail opening became habitual. George and his successors took a 
constant personal interest in the work, often encouraging talent with 
royal bounty . Correspondence was closely watched for cribs that were 
passed to the Decyphering Branch. 
During the 1700s, the branch's output averaged two or three 
dispatches a week, and sometimes one a day. Its cryptanalysts solved the 
dispatches of France, Austria, Saxony and other German states, Poland , 
Spain, Portugal , Holland , Denmark , Sweden, Sardinia, Naples and other 
Italian states, Greece, Turkey , Russia, and, later, the United States. The 
record of French interceptions covers two centuries and comprises five 
volumes of intercepts totaling 2,020 pages plus three volumes of keys. 
Perhaps more typical is the Spanish dossier—three volumes of intercepts 
from 1719 to 1839 totaling 872 pages. Not all of the messages were 
solved at the time of their interception. Many were held either until 
enough had accumulated for a successful attack or until a need arose for 
their solution. 
The solutions were read by the king and a few of the top ministers. 
They warned the government of the intrigues of foreign rulers and 
ambassadors and of impending war. An intercepted message between the 
Spanish ambassadors in London and Paris clearly suggested that Spain 
had allied herself with France against England in the Seven Years' War. 
It was read at the British cabinet meeting of October 2, 1761 . The Great 
Commoner, William Pitt the Elder , cited it as support for his proposal 
that England take the initiative, declare war before Spain did, and 
capture the fleet of treasure ships then transporting gold to Spain from 
her American possessions. His counsel was rejected, and he resigned. 
The war came anyway—after the immense cargo of bullion had been 
unloaded at Cadiz. 
In the 1840's, political gales blew down a great deal of 
the remaining absolutism and the totalitarian agencies that propped it 
up. Europe's new birth of freedom tolerated no government opening of 
mail. In England, a tremendous public and parliamentary outcry over the 
surreptitious opening of letters forced the government to discontinue the 
interception of diplomatic correspondence in June of 1844 . That October 
the government dissolved the Decyphering Branch, pensioning off Willes 
and Lovell. In Austria, the Geheime Kabinets-Kanzlei closed its doors in 
1848. In France, the Cabinet Noir, which had been withering ever since 
the Revolution, passed away as well in that convulsive year. And in that 
same decade, the same vast social forces that ended the era of the black 
chambers simultaneously fostered an invention that transformed 
cryptography. 
 
7.  The Contribution of the Dilettantes 
 
THE TELEGRAPH made cryptography what it is today. Samuel F. B. Morse 
sent "What hath God wrought!" in 1844. The next year his lawyer and 
promotional agent, Francis O. J. Smith, published a commercial code 
entitled The Secret Corresponding Vocabulary; Adapted for Use to Morse's 
Electro -Magnetic Telegraph, in whose preface he declared that "secrecy in 
correspondence, is far the most important consideration ." This was 
provided by a super-encipherment. 
As the most exciting invention of the first half of the century, the 
telegraph stirred as much interest in its day as Sputnik did in its. The 
great and widely felt need for secrecy awakened the latent interest in 
ciphers that so many people seem to have, and kindled a new interest in 
many others. Dozens of persons attempted to dream up their own 
unbreakable ciphers. Their contributions enriched it with dozens of new 
cipher systems. 
As businessmen and the public used the telegraph more and more, 
they found that their fears about lack of privacy were exaggerated. The 
clerks dealt impersonally with the messages. The telegraph companies 
respected their confidentiality. And commercial codes like Smith's, which 
replaced words and phrases by single codewords or code- 
numbers to cut telegraph tolls, afforded sufficient security for most 
business transactions by simply precluding an at-sight comprehension of 
the meaning. The brokers and traders soon realized that the main 
advantage of these codes was their economy. 
Government ministries used the telegraph, too. At first they must 
have encoded with their nomenclators. But although secrecy was 
paramount for them, they liked the telegraphic economy of a large code—
especially as they telegraphed more and more. So when the time arrived 
to compile a new nomenclator, they abandoned that form, copied the 
commercial form, and produced a full-fledged code. The nomenclators 
had had their 1,- or 2,000 code-numbers in mixed order, but the war 
and foreign ministries balked at the expense of drawing up a 50,000-
entry code in two parts, and they had no professional cryptanalysts to 
warn them of the danger of the one-part format. They relied for security 
upon small editions, big safes, extensive lexicon (large codes are harder 
to break than small ones, other things being equal), and 
superencipherment, retaining codenumbers to facilitate this instead of 
switching to codewords. This evolution was essentially complete by the 
1860s. The large, one-part code had replaced the small, two-part 
nomenclator in high-level military and diplomatic cryptography. 
Meanwhile, the telegraph, author of this development, was creating 
something new in war—signal communications, or voluminous command 
and reconnaissance messages. Of course such messages had existed 
before, with torches, pigeons, and couriers, but in so rarefied a form that 
they were not even called "signal communications." The telegraph 
enabled commanders, for the first time in history, to exert instantaneous 
and continuous control over great masses of men spread over large 
areas. 
These tactical messages required protection: telegraph wires could be 
tapped. Neither the old nomenclator nor the new code would do. They 
were too easy to capture in combat, too hard to reissue quickly and 
frequently to the numerous and widespread telegraph posts. Signal 
officers turned away from them. They looked instead to that neglected 
child of cryptography, the cipher. Ciphers could be printed cheaply on a 
single sheet of paper and distributed with ease. Secrecy was based upon 
variable keys, so capture of the general system and even of one of the 
keys would not compromise all an army's secret messages. Solutions 
would be prevented by rapid key changes. Ciphers were ideal for battle-
zone messages, and the first of the modern wars , the American Civil War, 
used them for just that. Thus was born a new genre in cryptography: the 
field cipher. 
The first one was waiting in the wings. This was poly-alphabetic 
substitution, in the form of the straight-alphabet Vigenere with short 
repeating keyword. The old objections to its use, which boiled down to 
the impossibility of correcting a garbled dispatch quickly enough, 
vanished with the telegraph. It fulfilled the requirements of noncom-
promisability of the general system and of ease of key changes. Moreover, 
it had the reputation of being unbreakable—which, if its cryptograms 
were not divided into words, it largely was. The military adopted it at 
once. 
Then, in 1863, a retired Prussian infantry major discovered the 
general solution for the periodic polyalpha- betic substitution. At one 
stroke he demolished the only impregnable structure in cryptography. 
Signal officers, compelled to provide secure communications, hunted 
frantically for new field ciphers. They found many good ideas in the 
writings of the dilettante cryptographers who had proposed ciphers for 
the protection of private messages. Soon some of these systems were 
serving in the various armies of Europe and the Americas. More ideas 
came from army officers who had studied cryptography in the courses in 
signal communication that the national military academies, such as St. 
Cyr, had added in the mid-1800s. Inevitably, cryptanalysts—who were 
either amateurs or soldiers with a professional interest, for full 
professionals there were none—replied with new techniques for breaking 
the new ciphers. From the slow crawl of nomenclator days, when the 
introduction of a special group meaning Disregard the preceding group 
would constitute a remarkable technical advance, the race between 
offense and defense in cryptology acclerated to its modern pace . 
The history of cryptology from the decade that saw both the death of 
the black chambers and the birth of the telegraph to World War I is thus 
a story of internal development. Without Rossignols or Willeses, and 
without major wars or diplomatic struggles, cryptology could not 
influence world events, and, except for one or two unusual cases, it did 
not. The telegraph launched this evolution 
of cryptology. It broke the monopoly of the nomenclator. The 
nomenclator had reigned for 450 years as a general, all-purpose system, 
but it could not meet the new requirements either of high-level 
diplomatic or military communications or of low-level signal 
communications, which the telegraph had engendered. Each called for its 
own kind of cryptosystem, a specialized one. Signal officers ranked these 
systems in a hierarchy, rising from the simple and flexible and easily 
solved to the extensive and hard to solve. The telegraph thus stimulated 
the invention of many new ciphers and, by reaction, many new methods 
of crypt-analysis, and compelled their arrangement in a scale of 
complexity. 
Many of these ciphers and techniques have become classic and are in 
use today. Moreover, cryptography still functions through a hierarchy 
and employs a multitude of special systems. The telegraph thereby 
furnished cryptography with the structure and the content that it still 
has. It made it what it is today. 
 
All these things have antecedents, and just as the telegraph itself did, 
so were there precursors of the cryptographic systems that it 
engendered. 
One cipher system invented before the telegraph was so far ahead of 
its time, and so much in the spirit of the later inventions , that it deserves 
to be classed with them. Indeed, it deserves the front rank among them, 
for this system was beyond doubt the most remarkable of all. So well 
conceived was it that today, more than a century and a half of rapid 
technological progress after its invention, it remains in active use. 
But then it was invented by a remarkable man, a well-known writer, 
agriculturalist, bibliophile, architect, diplomat, gadgeteer, and statesman 
named Thomas Jefferson . He called it his " wheel cypher," and it seems 
likely that he invented it either during 1790 to 1793 or during 1797 to 
1800. 
 
Turn a cylinder of white wood of about 2. Inches diameter & 6. 
or 8. I. long, bore through it's center a hole sufficient to receive an 
iron spindle or axis of Vs or 1A I. diam. divide the periphery into 
26. equal parts (for the 26. letters of the alphabet) and, with a 
sharp point, draw parallel lines through all the points 
of division from one end to the other of the cylinder, & trace 
those lines with ink to make them plain, then cut the cylinder 
crosswise into pieces of about V6 of an inch thick, they will 
resemble back-gammon men with plane sides , number each of 
them, as they are cut off, on one side, that they may be 
arrangeable in any order you please, on the periphery of each, and 
between the black lines, put all the letters of the alphabet, not in 
their established order, but jumbled & without order, so that no 
two shall be alike, now string them in their numerical order on an 
iron axis, one end of which has a head, and the other a nut and 
screw ; the use of which is to hold them firm in any given position 
when you chuse it. they are now ready for use, your correspondent 
having a similar cylinder, similarly arranged. 
Suppose I have to cypher this phrase. "Your favor of the 22d is 
received." 
I turn the 1" wheel till the letter y. presents itself 
I turn the 2* & place it's    .    .   o. by the side of the y. of the !•' wheel 
I turn the 3d & place it's    .    .   u. by the side of the o. of the 2a
4th.....r. by the side of the u. of the 3d
5">.....f. by the side of the r. of the 4th
6th.....a. by the side of the f. of the 5th
and so on till I have got all the words of the phrase arranged in 
one line, fix them with the screw, you will observe that the cylinder 
then presents 25. other lines of letters, not in any regular series, 
but jumbled, & without order or meaning, copy any one of them in 
the letter to your correspondent, when he receives it, he takes his 
cylinder and arranges the wheels so as to present the same 
jumbled letters in the same order in one line, he then fixes them 
with his screw, and examines the other 25. lines and finds one of 
them presenting him these letters: "yourfavorofthe 22isreceive d." 
which he writes down, as the others will be jumbled & have no 
meaning, he cannot mistake the true one intended, so proceed 
with every other portion of the letter, numbers had better be 
represented by letters with dots over them; as for instance by the 
6. vowels & 4. liquids, because if the periphery were divided into 
36. instead of 26. lines for the numerical, as well as alphabetical 
characters, 
it would increase the trouble of finding the letters on the wheels. 
When the cylinder of wheels is fixed , with the jumbled 
alphabets on their peripheries, by only changing the order of the 
wheels in the cylinder, an immense variety of different cyphers may 
be produced for different correspondents, for whatever be the 
number of wheels, if you take all the natural numbers from unit to 
that inclusive, & multiply them successively into one another, their 
product will be the number of different combinations of which the 
wheels are susceptible, and consequently of the different cyphers 
they may form for different correspondents, entirely unintelligible 
to each other. . . . 
 
Jefferson went on to say that if the cylinder be six inches long ("which 
probably will be a convenient length, as it may be spanned between the 
middle finger & thumb of the left hand, while in use") the number of 
wheels would total 36, and the number of ways in which they can be 
strung on the spindle to form different ciphers for different 
correspondents would come to 36 factorial, or 1 X 2 X 3 X ... X 35 X 36, 
which Jefferson calculated almost exactly as "372 with 39 cyphers [zeros] 
added to it." In fact, 36 factorial is 
371,993,326,789,901,217,467,999,448,150,835, 200,000,000. 
Had the President recommended his own system to Secretary of State 
James Madison, he would have endowed his country with a method of 
secret communication that would almost certainly have withstood any 
cryptanalytic attack of those days. Instead he appears to have filed and 
forgotten it. It was not rediscovered among his papers in the Library of 
Congress until 1922, coincidentally the year the U.S. Army adopted an 
almost identical device that had been independently invented. Later, 
other branches of the American government used the Jefferson system, 
generally slightly modified, and it often defeated the best efforts of the 
20th-century cryptanalysts who tried to break it down! To this day the 
Navy uses it. This is a remarkable longevity. So important is his system 
that it confers upon Jefferson the title of Father of American 
Cryptography. 
 
[Codebreakers 117.jpg]
 
Charles Wheatstone had a remarkably fertile mind. He constructed an 
electric telegraph before Morse did, invented 
 
the concertina, improved the dynamo , studied underwater telegraphy, 
produced some of the first stereoscopic drawings, published half a dozen 
papers on acoustics, discussed phonetics and hypothetical speaking 
machines in print, conducted numerous electrical experiments, and 
popularized a method for the extremely accurate measurement of 
electrical resistance now in frequent use and called the "Wheatstone 
bridge." His work was highly enough regarded for him to be elected a 
fellow of the Royal Society and to be knighted. He was nominally 
professor of experimental 
philosophy at King's College, London, but was so excessively shy that 
he hardly ever actually lectured. 
Another of his inventions was a cipher for secrecy in telegraphy, 
which, however, carries the name of his friend Lyon Playfair, first Baron 
Playfair of St. Andrews. A scientist and public figure of Victorian 
England, Playfair was at one time or another deputy speaker of the 
House of Commons, postmaster general, and president of the British 
Association for the Advancement of Science. 
Playfair demonstrated what he called "Wheatstone's newly-discovered 
symmetrical cipher" at a dinner in January, 1854, given by the president 
of the governing council, Lord Granville. One of the guests was Queen 
Victoria's husband, Prince Albert ; another was the Home Secretary and 
future Prime Minister, Lord Palmerston. Playfair explained the system to 
him, and, while in Dublin a few days later, received two short letters in 
the cipher from Palmerston and Granville, showing that both had readily 
mastered it. 
The cipher is the first literal one in cryptologic history to be 
digraphic*—that is, to encipher two letters so that the result depends 
upon both together. Wheatstone recognized that the cipher would work 
as well with a rectangle as with a square, but it soon petrified into the 
latter form. Playfair thus constructed a square based on PALMERS-TON, 
with the remaining letters of the alphabet following, to illustrate the 
cipher at Granville's dinner: 
PALME R S T O N B C D F G H IJ K Q U V W X Y Z 
To encipher, the plaintext is divided into pairs . Double letters 
occurring together in a pair must be separated with an x, so that balloon 
would be enciphered as ba Ix lo on; i and / are regarded as identical, so 
that adjacent will be enciphered as if it were adjiacent. Now the letters of 
each pair may stand in only three relationships to one another within the 
square: the two may appear in the same row, in the same column, or in 
neither. Letters that fall in the 
*An earlier author's digraphic table used not letters but signs. 
same row are each replaced by the letter to its right. Thus, am = LE, hi 
= IK, os = NT. Each row is considered cyclical, so that the letter to the 
right of the last letter in a row is the first letter at the left of that row. 
Thus, le = MP, ui — HK. Letters that appear in the same column are each 
replaced by the letter beneath it; the cyclical provision holds. Thus, ac = 
sj (or si, as the encipherer wishes); of = FQ, wi — AW, br = HB. 
If the plaintext letters appear in neither the same row nor the same 
column, each is replaced by the letter that lies in it's own row and stands 
in the column occupied by the other plaintext letter. For example, to 
encipher sq, the encipherer first locates them in the square. Then he 
runs across the row of the first plaintext letter (s) until he meets the 
column in which the second plaintext letter (q) stands: 
.     M    . 
R    S    T    O    N 
.      .       .     F     . 
.      •      •     Q     • 
.     Y     . 
The letter at the junction of row and column (o) becomes the first 
cipher letter. Then the encipherer traces across the row of the second 
plaintext letter (q) until he intersects the column in which the first 
plaintext letter stands: 
.     A     ... 
5     ... 
.     C     .      .      . 
H    IJ    K    Q    U 
.    W     . 
The letter at the intersection (i) becomes the second cipher letter. 
Thus sq = 01. Other encipherments are af = MC, at = LS, ed — LG. The 
letter in the row of the first plaintext letter is always taken first to 
preserve the order of the letters, so that cl — DA and not AD, which would 
stand for le, and \ve = ZA. 
Decipherment in this is precisely the same as encipher- ment : if ow = 
SY, then sy — ow. In the other two cases, the plaintext letters are found 
to the left or above the ciphertext letters. Thus, using the same square, a 
ciphertext reduces as follows: 
MT   TB   BN   ES   WH   TL   MP   TA   LN   NL   NV 
lo    rd   gr   an    vi    Ix    le    si    et    te    rz 
The z at the end is a null to complete the final digraph. 
Wheatstone and Playfair explained the cipher to the Under Secretary 
of the Foreign Office, no doubt pointing out its chief advantage—that two 
plaintext pairs that have a letter in common may not display the slightest 
resemblance in ciphertext, as le and te above were enciphered to MP and 
NL. Further, once mastered, it rolls along with remarkable ease and 
rapidity. When the Under Secretary protested that the system was too 
complicated, Wheatstone volunteered to show that three out of four boys  
from the nearest elementary school could be taught it in 15 minutes. The 
Under Secretary put him off. "That is very possible," he said, "but you 
could never teach it to attaches." 
Playfair, reasoning that this reflected more on the diplomats than on 
the cipher, remained enthusiastic about it. There were good grounds for 
enthusiasm . In the first place, the cipher's being digraphic obliterates the 
single-letter characteristics—e, for example, is no longer identifiable as 
an entity. This undercuts the usual monographic methods of frequency 
analysis. Secondly, encipherment by digraphs halves the number of 
elements available for frequency analysis. A 100-letter text will have only 
50 cipher digraphs. In the third place, and most important, the number 
of digraphs is far greater than the number of single letters, and 
consequently the linguistic characteristics spread over many more 
elements and so have much less opportunity to individualize themselves. 
There are 26 letters but 676 digraphs; the two most frequent English 
letters, e and t, average frequencies of 12 and 9 per cent; the two most 
frequent English digraphs, th and he, reach only 31/* and 2V2 per cent. 
In other words, not only are there more units to choose among, the units 
are less sharply differentiated. The difficulties are doubly doubled. 
These properties elevated the cipher above most of its contemporaries 
purely on cryptographic considerations; it was, properly, regarded as 
unbreakable. Its many practical excellences—no tables or apparatus 
required, a keyword that could easily be remembered and changed, great 
simplicity of operation—commended it as a field cipher. Play-fair 
suggested that it be used as just that in the impending 
Crimean War when he brought it up at the dinner with Prince Albert. 
No evidence exists that it was used then, but there are reports that it 
served in the Boer War. Britain's War Office apparently kept it secret 
because it had adopted the cipher as the British Army's field system. 
Playfair's unselfish proselytizing for his friend's system unwittingly 
cheated Wheatstone of his cryptographic heritage; though Playfair never 
claimed the invention as his own, it came to be known in the War Office 
as Playfair's Cipher, and his name has stuck to it to this day. 
 
Five years later, an American who at the time was working for a stove 
and foundry firm glanced briefly at cryp-tology and produced a single 
short piece of work. It opened important new vistas into untrodden 
lands—and then sank immediately into a cryptologic obscurity. 
The inventor was Pliny Earle Chase , then 39, who, after entering 
Harvard as a prodigy at 15, taught in Philadelphia for seven years until 
his health forced him into less tiring work in business. In 1861 he 
resumed teaching, becoming professor of natural science and then 
professor of philosophy and logic at Haverford College near Philadelphia. 
He was an absorbing lecturer, particularly in astronomy, and he 
collaborated on an arithmetic textbook with Horace Mann. But perhaps 
his most notable accomplishment was his writing more than 250 articles 
for scholarly magazines. Among them was the one that he penned in 
1859 which covered barely three pages in the new Mathematical Monthly, 
but which constitutes the first published description of fractionating, or 
tomographic, cipher systems. 
The basis of these ciphers stretches back across the millennia to 
Polybius, the Greek historian of the second century B.C. who distributed 
the alphabet in what is even today sometimes called a "Polybius square," 
but more often a "checkerboard." Numbers at the side and top indicate 
the row and the column of a given letter. Similar systems have cropped 
up throughout cryptography. Some replace the alphabet by three 
symbols in groups of three (a = 111, b — 112, c — 113, d — 121, etc.), 
some by two in groups of five (a = 00000 , b = 00001, c = 00010, etc.). But 
no one seems to have seen the symbols as manipulable entities instead 
of just as an unalterable part of the whole. 
Until Chase. He severed the coordinates from one another and 
subjected the resulting fractions to various crypto- 
graphic treatments. He began with a checkerboard filled out to ten 
columns with Greek letters: 
                             
                           6  
                             
                             
Chase wrote his coordinates vertically, so that his sample plaintext, 
Philip, appeared like this: 
133131 959899 
He then multiplied the lower line by 9, obtaining the result: 
133131 8639091 
This he restored to literal form by resubstituting back in his 
checkerboard, 8 (by itself) = L, j, or T, then 16 = N, 33 = s, 39 = i, and so 
on, with the final ciphertext 
LNSl4>IX. 
Chase proposed other means of transforming the bottom row, such as 
adding a repeating key or giving the logarithm of the row, and pointed 
out that even more intricate processes might be used. "But the simpler 
cypher, provided it is effectual, is the better," he wisely concludes. The 
Chase systems grant a fairly hermetic security; they are, besides, 
relatively simple to operate. Yet cryptologic history shows no one ever 
having used them, even though they are far superior to many systems 
that have seen service. 
 
Of the man who did explode the bomb that gouged new channels for 
cryptology, little more is known than the bare outline provided by his 
service record. This is complete if not detailed, for Friedrich W. Kasiski 
spent his entire professional career as an officer in East Prussia's 33rd 
Infantry Regiment. Born November 29, 1805, in what was then 
Schlochau, West Prussia, and is now Czluchow, Poland, he enlisted in 
the regiment at 17. He won his commission as a second lieutenant three 
years later, in 1825—and did not budge out of that rank for 14 years. 
But he remained a 
first lieutenant only three years before he was promoted to captain 
and company commander, a post he held for nine years. He retired in 
1852 with the rank of major, and though he served from 1860 to 1868 as 
the commander of a National Guard-like battalion, he found sufficient 
leisure to devote some to cryptology, for in 1863 his short but epochal 
book was published in Berlin by the respected house of Mittler & Sohn. 
Three quarters of Die Geheimschriften und die Dechif-frir- kunst  
concentrates on answering the problem that had vexed cryptanalysts for 
more than 300 years: how to achieve a general solution for 
polyalphabetic ciphers with repeating keywords. (One chapter zeroes in 
on "The Decipherment of French Writing"—a rather ominous portent in a 
book dedicated to the Count Albrecht von Roon, the Prussian minister of 
war who molded the army that humbled France only seven years later.) 
The polyalphabetic solution opened the doors to the cryptology of today. 
But the 95-page volume seems to have stirred almost no comment at the 
time. Kasiski himself lost interest in cryptology. He became an avid 
amateur anthropologist, joining the Natural Science Society of Danzig, 
unearthing prehistoric graves , and reporting on his work to learned 
journals. (One of his scholarly articles was cited in the Encyclopaedia 
Britannica.) Kasiski died on May 22, 1881, almost certainly without 
realizing that he had wrought a revolution in cryptology. 
That revolution began when Kasiski shrewdly noted a phenomenon: 
the conjunction of a repeated portion of the key with a repetition in the 
plaintext produces a repetition in the ciphertext: 
key          RTJNRTJNRUNRUNRTJNRUNRUNRTJNRtJNRUN 
plaintext tobeornot tobethatisthequestion ciphertext KIO v i E E i o K I o 
v NUB N v J N u VKHVMQZ I A 
Each time that the key RUNR engages the repeated plaintext to be, the 
repeated ciphertext tetragraph KIOV results. Like causes produce like 
effects . Similarly, when the repeated key-fragment UN operates upon the 
repeated th's, the ciphertext registers repeated NU'S. 
Clearly, the keyword must repeat one or more times for a given part of 
it to encipher two identical bits of plaintext several letters distant from 
one another. The number of letters between the two resultant ciphertext 
repetitions will 
 
itwv_uu inc numoer or times that the keyword has repeated. The 
count of the interval "between" the two repetitions actually includes 
repeated letters. Thus the interval between the first KIOV and the second 
is 9, figured like this: 5 letters not repeated and 4 that are. This interval 
of nine results from the fact that the keyword has three letters and has 
repeated three times. These repetitions betray the movements of the 
keyword beneath the surface of the cryptogram just as the ducking of a 
fishing cork tells of a nibble. Kasiski said to locate all repetitions in the 
cryptogram and then to "calculate the distance separating the repetitions 
from one another. . . . and endeavor to break up this number into its 
factors. . . . The factor most frequently found indicates the number of 
letters in the key." For example, an interval of 60 will show factors of 2 X 
2 X 3 X 5. If the factors of 2 X 3 occur in most of the calculations, the 
keyword probably has six letters in it. Now, knowledge of how many 
letters are in the keyword tells how many alphabets were used in the 
polyalphabetic encipher-ment. This information permits the cryptanalyst 
to sort the letters of the cryptogram so that all those enciphered with the 
first keyletter are brought together in one group, all those enciphered 
with the second keyletter in another group and so forth. Since all of the, 
say, e's in the first group were converted under the influence of a single 
key-letter to the same ciphertext, all of the a's to one ciphertext letter, 
and so on, each of these collections of letters constitutes a 
monoalphabetic substitution cipher and so can be solved like one. When 
he reassembles these, he will have the plaintext to an "unbreakable" 
cipher. 
 
It was France, however, that published one of cryptol-ogy's greatest 
books. La Cryptographic militaire first appeared as two installments in 
the  Journal  des Sciences militaires in January and February of 1883, 
being reissued later that year as a paperback book by the journal's 
publisher. It is the most concise book on cryptology ever written. Its 
author had the instinct for the cryptographic jugular, and he compressed 
into 64 pages virtually the entire known field of cryptology, including 
polyalphabetics with mixed alphabets, enciphered code, and cipher 
devices. The book is also one of the most scholarly on cryptology. Its 
footnotes cite most classical and many modern sources; comments such 
as "This is not the only historical or 
bibliographic error for which the Austrian writer must be reproached" 
show how carefully the author has studied those sources. 
Its author was born Jean- Guillaume -Hubert- Victor -Frangois-
Alexandre - Auguste Kerckhoffs von Nieuwenhof on January 19, 1835, at 
Nuth, Holland. After getting degrees in letters and in science from the 
University of Liege, he was hired in 1863 as an instructor in modern 
languages at the high school at Melun, a large town 25 miles southeast 
of Paris. The next year he married a girl from the area and in 1865, when 
he was 30, they had their only child, a daughter, Pauline . He stayed at 
Melun for 10 years, teaching English and German. 
By that time he had shortened his name to Auguste Kerckhoffs. 
Bearded, dignified, slow of speech , Kerckhoffs, despite an inability to 
maintain discipline in his classes and some eccentricities of character, 
was a "learned, zealous, capable" teacher who awoke his students' 
interest in their work; his superiors said "his students like him and work 
with success." Afterward, he worked as a private instructor in Paris. 
His busiest years followed the publication of La Cryptographic 
militaire. A new international language called Vola- piik ("World-Speak") 
had been invented by a German priest. About 1885, it caught on in 
France and flashed with express- train speed all over the country, not 
only among intellectuals but among all classes; it was even heard in the 
streets. From France it radiated throughout the world. The most active 
propagandist of Volapiik was Auguste Kerckhoffs, who, at the second 
Volapiik congress in Munich in 1887, was acclaimed director ("Dilekel," 
in Volapiik) of the International Academy of Volapiik. But at the third 
congress, held at Paris in May of 1889, with Kerckhoffs presiding, critical 
tensions within the movement mounted and finally broke it apart. 
Kerckhoffs was crushed by the collapse of an international dream that 
had seemed so needful and so certain. He created nothing else and, on 
August 9, 1903, died while on vacation in Switzerland. 
But his cryptologic ideas still nourish. For Kerckhoffs sought answers 
to the problems thrust upon cryptology by new conditions. "It is 
necessary to distinguish carefully between a system of encipherment 
envisioned for a momentary exchange of letters between several isolated 
people 
and a method of cryptography intended to govern the correspondence 
between different army chiefs for an unlimited time," he wrote. In that 
one sentence, Kerckhoffs differentiates pre-telegraphy military 
communications from post-. The sentence is pregnant with most of the 
requirements that have come to be demanded of systems of military 
cryptography, requirements such as simplicity, reliability , rapidity, and 
so on. This clear recognition of the new order constitutes Kerckhoffs' first 
great contribution to cryptology. 
The second was to reaffirm in a modern context the principle that only 
cryptanalysts can know the security of a cipher system. It is the form of 
judgment which is still used. 
From these two fundamental principles for selecting usable field 
ciphers, Kerckhoffs deduced six specific requirements: (1) the system 
should be, if not theoretically unbreakable, unbreakable in practice; (2) 
compromise of the system should not inconvenience the correspondents; 
(3) the key should be rememberable without notes and should be easily 
changeable; (4) the cryptograms should be transmissible by telegraph; (5) 
the apparatus or documents should be portable and operable by a single 
person; (6) the system should be easy, neither requiring knowledge of a 
long list of rules nor involving mental strain. 
These requirements still comprise the ideal which military ciphers aim 
at. They have been rephrased, and qualities that lie implicit have -been 
made explicit. But any modern cryptographer would be very happy if any 
cipher fulfilled all six. 
Of course, it has never been possible to do that. There appears to be a 
certain incompatibility among them that makes it impossible to institute 
all of them at once. The requirement that is usually sacrificed is the first. 
Kerckhoffs argued strongly against the notion of a field cipher that would 
simply resist solution long enough for the orders it transmitted to be 
carried out. This was not enough, he said, declaring that "the secret 
matter in communications sent over a distance very often retains its 
importance beyond the day on which it was transmitted." He was on the 
side of the angels , but a practical field cipher that is unbreakable was 
not possible in his day, nor is it today, and so military cryptography has 
settled for field ciphers that delay but do not defeat cryptanalysis. 
Perhaps the most startling requirement, at first glance, 
was the second. Kerckhoffs explained that by "system" he meant "the 
material part of the system; tableaux, code books, or whatever 
mechanical apparatus may be necessary," and not "the key proper." 
Kerckhoffs here makes for the first time the distinction, now basic to 
cryptology, between the general system and the specific key. Why must 
the general system "not require secrecy," as, for example, a codebook 
requires it? Why must it be "a process that. . . our neighbors can even 
copy and adopt"? Because, Kerckhoffs said, "it is not necessary to 
conjure up imaginary phantoms and to suspect the incorruptibility of 
employees or subalterns to understand that, if a system requiring 
secrecy were in the hands of too large a number of individuals, it could 
be compromised at each engagement in which one or another of them 
took part." This has proved to be true, and Kerckhoffs' second 
requirement has become widely accepted under a form that is sometimes 
called the fundamental assumption of military cryptography: that the 
enemy knows the general system. But he must still be unable to solve 
messages in it without knowing the specific key. In its modern 
formulation, the Kerckhoffs doctrine states that secrecy must reside  
solely in the keys. 
Had Kerckhoffs merely published his perceptions of the problems 
facing post-telegraph cryptography and his prescriptions for resolving 
them, he would have assured a place for himself in the pantheon of 
cryptology. But he did more. He contributed a technique of cryptanalysis 
that is of supreme importance today. Called "superimposition," it 
constitutes the most general solution for polyalphabetic substitution 
systems. With few exceptions, it lays no restrictions on the type or length 
of keys, as does the Kasiski method, nor on the alphabets, which may be 
interrelated or entirely independent. It wants only several messages in 
the same key. The cryptanalyst must align these one above the other so 
that letters enciphered with the same keyletter will fall into a single 
column. In the simplest case, that of a running key (a very long 
continuous text used as a key, as a novel ) that restarts with each 
message, he can do this simply by placing all the first letters in the first 
column, all the second letters in the next column, and so on. 
Kerckhoffs demonstrated this procedure with 13 short messages 
enciphered with a long key. He superimposed his first five cryptograms 
like this: 
  
3
1
1
1
                         0  21 4 15 
4  
11  3   . .  
Mess
Y
C
A
M 
age 1   J                                    T     
B  
F   M   . .  
Mess
W
I
L
R
age 2   J         P                           E     
B   W   . .  
Mess
W
M M G 
age 3                               T     J      
H  
V   . .  
Mess
V
C
W G 
age 4   r                                   H    . 
R  
W   E   .  
Mess
8
C
W V 
age 5                                       X    . 
H  
J   Z   .  
Now, since all these messages were enciphered with the same keytext, 
all the hidden plaintext letters in the first column were enciphered by the 
same keyletter, which means that they have been enciphered in the same 
cipher-text alphabet. Consequently, all the plaintext a's will have the 
same ciphertext equivalent, all the plaintext b's will likewise have their 
own unvarying ciphertext equivalent, and so on. Likewise, each 
ciphertext letter represents only one plaintext letter. This holds true for 
each column. Each column may thus be attacked as an ordinary 
monalpha-betic substitution, just as Kasiski did with identically 
enciphered letters in a periodic polyalphabetic. 
In cases where the key does not start over again with each message, 
the cryptanalyst may line up repetitions in several messages to obtain a 
proper superimposition. 
 
It is ironic that the most lasting work of a man whose ideals were as 
cosmopolitan as Kerckhoffs' should have had nationalistic results. Yet 
perhaps the most immediate consequence of La Cryptographic militaire 
was its giving France a commanding lead in cryptology. The flowering of 
cryptologic literature that it engendered there reflected that nation's 
profound understanding of the subject. And French solution of Italian 
and German diplomatic codes, which allowed her to read critical German 
messages on. the very eve of World War I, demonstrated her practical 
capabilities. The army at the same time prepared, through a Military 
Cryptography Commission, for the solution of enciphered German radio 
messages. These would be intercepted by the major fortress stations in 
the northeast that faced Germany. 
Of the other major countries of Europe, only Austria- Hungary had 
prepared cryptanalytically for the war. The Dual Monarchy began to 
intercept the radio messages of her arch -rival Italy in 1908. In 1911, with 
the Italo -Turkish conflict, Captain Andreas Figl became the chief of a 
newly 
formed cryptanalytic bureau that was to do remarkable work. Other 
nations remained ignorant . England, Germany, and Russia made no 
preparations whatsoever for military radio intelligence. It was about their 
only failure in readying for the expected conflict. Finally, in an obscure 
corner of the Balkans, someone helpfully slew an archduke, and the 
nations leaped recklessly into the bloody cockpit of war. 
 
8.  Room 40 
 
BEFORE DAWN on the morning of August 5, 1914, the first day of a world 
war that was to convulse country after country and to end the lives of 
millions, an equipment-laden ship slid quietly through the black and 
heaving waters of the North Sea. Off Emden, where the Dutch coast joins 
the German, she dropped some grappling gear overboard with a dull 
splash, and shortly there rose dripping from the sea great snakelike 
monsters, covered with mud and seaweed. Grunts of men, chopping 
sounds—and soon they were returned, severed and useless, to the 
depths. These were Germany's transatlantic cables, her chief 
communications lifelines to the world, and the vessel was the British 
cable ship Telconia. Though the Committee of Imperial Defence never 
dreamed of it when it planned the move in 1912, the cutting of these 
cables, England's first offensive action of the war, forged the first link in 
a chain that helped to end it. 
Germany was now forced to communicate with the World beyond the 
encircling Entente by radio or over cables controlled by her enemies. She 
thus delivered into the hands of her foes her most secret and confidential 
plans, provided only that they could remove the jacket of code and cipher 
in which Germany had encased them. It Was an opportunity for which 
England was unprepared, but of which she promptly availed herself. 
On that first day of the war, the director of naval intelligence, Rear 
Admiral Henry F. Oliver, walked to lunch With the only man at the 
Admiralty to take any interest in cryptology, the director of naval 
education, Sir Alfred 
p 
Ewing. A few months before, Ewing had devised what he later called a 
"futile" ciphering mechanism, and he had spoken to Oliver about new 
methods of constructing ciphers. Oliver mentioned that some naval and 
commercial radio stations were sending to the Admiralty some messages 
in code that they had picked up and that these were accumulating on his 
desk. The Admiralty had no department to deal with enemy cryptograms, 
he said. Ewing was at once interested, and when he saw the messages 
that afternoon he recognized that they were probably German naval 
signals and that their solution could be of great value. He promptly 
undertook the task. 
Ewing was then 59, a short, thickset Scot with blue eyes beneath 
shaggy eyebrows, a quiet voice, and the manner of a benign physician. 
He had been knighted three years before for his contributions to science, 
which included pioneering studies of Japanese earthquakes, of 
magnetism , and of mechanical lagging effects in stressed materials (now 
known by a word he coined, "hysteresis"), and for his public services, 
notably his naval education directorship. He was to become president of 
the British Association for the Advancement of Science and perhaps his 
country's greatest living expert on mechanical science. And now he was 
about to found a cryptanalytic bureau that was to become almost 
legendary and to exert a direct and noticeable effect upon the course of 
history. 
He began by boning up on ciphers in the stacks of the British 
Museum library and on the construction of codes at Lloyd's of London 
and at the General Post Office, where commercial codebooks were on file. 
He called in four teachers at the naval colleges at Dartmouth and 
Osborne , A. G. Denniston, W. H. Anstie, E. J. C. Green , and G. L. N. 
Hope, all friends of his with a good knowledge of German, and, sitting 
together around the table in his office, they inspected the 
incomprehensible lines of letters and numbers with only the feeblest 
general idea on how to begin. 
None of the small band of pioneers had had any real previous 
knowledge of cryptanalysis, and they made only antlike progress in those 
first weeks. But Ewing was exhilarated by the job, and it was not until 
October 25 that he took a Sunday off. By then, England had had a stroke 
of fortune that gave such an impetus to its cryptanalytic work that it 
remained far ahead of its enemies through the rest 
of the war. What happened has best been told in his own style by the 
minister who then headed the Admiralty, the First Lord, Winston  
Churchill: 
 
At the beginning of September, 1914, the German light cruiser 
Magdeburg was wrecked in the Baltic . The body of a drowned 
German under-officer was picked up by the Russians a few hours 
later, and clasped in his bosom by arms rigid in death, were the 
cypher and signal books of the German Navy and the minutely 
squared maps of the North Sea and Heligoland Bight. On 
September 6 the Russian Naval ATTACHÉ came to see me. He had 
received a message from Petrograd telling him what had happened, 
and that the Russian Admiralty with the aid of the cypher and 
signal books had been able to decode portions at least of the 
German naval messages. The Russians felt that as the leading 
naval Power, the British Admiralty ought to have these books and 
charts. If we would send a vessel to Alexandrov, the Russian 
officers in charge of the books would bring them to England. We 
lost no time in sending a ship, and late on an October afternoon 
Prince Louis [of Battenberg, First Sea Lord] and I received from the 
hands of our loyal allies these sea-stained priceless documents. 
 
The date was October 13. But even this astounding windfall—the 
luckiest in the whole history of cryptology—did not enable Ewing's team 
to read the German naval messages, for the four-letter codewords in that 
book did not appear in the dispatches. Finally, Fleet Paymaster Charles 
J. E. Rotter, a principal German expert, discovered that the code had 
been superenciphered with a monoalphabetic substitution. Solution of 
such a superencipherment is not too difficult a problem with the 
codebook in one's possession. As in ordinary plaintext, certain codewords 
recur more frequently than others and in familiar clusters, letters in one 
codeword reappear in others in different arrangements, and the 
codewords themselves possess some structural regularities: in the case 
of the German naval code, consonants alternated with vowels in the four-
letter codewords. When these characteristics are known, the crypt-
analyst can spot them almost as well as the more pro- 
 
nounced ones of ordinary language, and can exploit them to solve the 
superencipherment. 
So green were the British cryptanalysts that it took them almost three 
weeks before they began reading portions of some German naval 
messages. These, Churchill says, "were mostly of a routine character. 
'One of our torpedo boats will be running out into square 7 at 8 p.m.,' 
etc. But a careful collection of these scraps provided a body of 
information from which the enemy's arrangements in the Heligoland 
Bight [bordering the northwest German coast] could be understood with 
a fair degree of accuracy." 
By this time, Ewing's staff had grown to such an extent that they 
crowded his office, and they were continually irked by having to put their 
work out of sight when he had visitors on educational subjects . So about 
the middle of November the entire cryptanalytic group moved to Room 40 
in the Old Buildings of the Admiralty. This was a large room with a small 
room adjoining, with a camp bed for tired staffers. Room 40, O.B., had 
the advantage of being out of the main stream of Admiralty traffic, yet 
being relatively handy to the Operations Division, which received its 
output. Though the cryptanalysts were later designated as I.D. 25 
(section 25 of the Intelligence Division), "Room 40" was so convenient and 
so innocuous a name that it soon became the common identification for 
the organization. The name stuck even when I.D. 25 moved into larger 
quarters. 
Meanwhile, naval intelligence was building up activities concomitant 
to cryptanalysis. Major radio direction-finding stations were—largely 
thanks to Oliver's foresight—set up at Lowestoft, York, Murcar, and 
Lerwick; they fed their readings into Whitehall, where they proved of 
immense help in locating the German fleets and the movement of the U-
boats. There was no way of avoiding a fix except by maintaining radio 
silence. This fact was of course known to the Germans, and in view of it 
England made no attempt to keep its direction-finding activity secret, 
using it as a smokescreen for its less obvious and more valuable 
cryptanalytic work. Two other sources of radio intelligence were the 
identification of ships' radio call-signs and the recognition of a radio 
operator's "fist," or characteristic way of sending Morse code. 
After Jutland, the German emphasis on submarine warfare intensified 
Room 40's concentration on the U- boat  
messages. These were encoded in the four-letter code of the High Seas 
Fleet, but were superenciphered by columnar transposition. The 
Germans called the one for the regular U-boats " gamma epsilon " and 
that for the larger cruising submarines, whose keyword differed, "gamma 
u." Keywords changed often but not daily. Three or four staffers 
specialized in this; they became so adept that they usually managed not 
only to restore the scrambled codewords to their original form but even to 
recover the keyword for the transposition tableau. The solutions greatly 
assisted British operations, and eventually the Germans could no longer 
chalk off as coincidental the repeated apparitions of substantial British 
units athwart their course. In August of 1916, they changed their code. 
But Room 40's direction-finding and call-sign sections were so well oiled 
that they nevertheless maintained a fair flow of intelligence. More help 
came from divers who recovered codes from sunken U-boats. 
These finds helped the cryptanalysts in reading the increasing volume 
of enemy messages. Room 40 was now approaching the height of its 
power. Intercepts poured in through the pneumatic tube so fast that at 
times the discharge of its small containers sounded like a machine gun. 
(After the war it was estimated that from October, 1914, to February, 
1919, Room 40 had intercepted and solved 15,000 German secret 
communications.) Work went on round the clock on the naval messages, 
even during the Zeppelin bombings, when the lights were dimmed behind 
the close-fitting dark blinds. The staff was further increased by wounded 
officers and by German university scholars, many of whom were 
commissioned in the Royal Navy Volunteer Reserve so that they could 
wear uniforms to forestall icy looks from the public. Women were enlisted 
to free cryptanalysts from clerical tasks. 
The most important personnel change came with the retirement of 
Ewing and his replacement as immediate overseer of Room 40 by the 
director of naval intelligence. Captain William Reginald Hall, R.N., 
unforgettably impressed all who met him. A dapper, alert man with a 
perfectly domed, prematurely bald head and a large hooked nose , Hall, 
then in his middle forties, looked like a demonic Mr. Punch in uniform . 
The American ambassador, Walter Hines Page, summed him up best in a 
letter to President Woodrow Wilson : "Hall is one genius that the 
war has developed. Neither in fiction nor in fact can you find any such 
man to match him. Of the wonderful things that I know he has done, 
there are several that it would take an exciting volume to tell. The man is 
a genius—a clear case of genius. All other secret-service men are 
amateurs by comparison." 
 
At about half-past ten on the morning of January 17, 1917, the 
Reverend William Montgomery , a thin, gray-haired scholar of the early 
church fathers who was serving as a cryptanalyst in the diplomatic 
section of Room 40, came to tell Hall of what looked like an important 
message. Montgomery's instincts were right. The cryptogram that he and 
a youthful colleague, Nigel de Grey , had partially read was to become the 
single most far-reaching and most important solution in history. 
The message was a long one, consisting of about a thousand 
numerical codegroups. Dated at Berlin January 16, it was addressed to 
the German ambassador in the United States, Count Johann Heinrich 
Andreas von Bern -storff, and the two cryptanalysts recognized that it 
was encoded in a German diplomatic code known as 0075, upon which 
they had been working for six months. Room 40 knew from its analyses 
that 0075 was one of a series of two-part codes that the German Foreign 
Office designated by two zeros and two digits, the two digits always 
showing an arithmetical difference of 2. Among the others, some of which 
Room 40 had solved, were 0097, 0086, which was used for German 
missions in South America, 0064, used between Berlin and Madrid and 
perhaps elsewhere, 0053, and 0042. Code 0075 was a new code that the 
German Foreign Office had first distributed in July of 1916 to German 
missions in Vienna, Sofia , Constantinople, Bucharest, Copenhagen, 
Stockholm, Bern, Lugano, The Hague, and Oslo . Somehow the British 
obtained copies of enough of the telegrams in this code to enable 
Montgomery and de Grey, whose assignment it probably was, to make a 
start in breaking it. In November, Room 40 began intercepting messages 
to the German embassy in the United States in the same code, and if 
Hall guessed that the code and the keys to the superencipherment that it 
sometimes used had been sent across the Atlantic on the second voyage  
of the cargo U-boat  Deutschland , which 
docked at New London on November 1, 1916, he would have been 
right. 
Montgomery and de Grey could read only parts of the long message. 
But they could see that it was a double-decker, consisting of Berlin's 
messages Nos. 157 and 158 to Bernstorff. They could read the signature 
of the German Foreign Minister, Arthur Zimmermann. As far as they 
could extricate its sense on the basis of their partial solution of 0075, the 
second message read: 
 
Most secret for your Excellency's personal informa-, tion and to 
be handed on to the Imperial Minister in (? Mexico ) with Telegram 
No.  1  (...) by a safe route. 
We propose to begin on the 1st February unrestricted 
submarine warfare. In doing so, however, we shall endeavor to 
keep America neutral . (?) If we should not (succeed in doing so) we 
propose to (? Mexico) an alliance upon the following basis: 
[joint] conduct of the war. 
[joint] conclusion of peace. 
(...) 
Your Excellency should for the present inform the President [of 
Mexico] secretly (? that we expect) war with the U.S.A. (possibly) (. . 
.) (Japan) and at the same time to negotiate between us and Japan. 
(Please tell the President) that (. . .) or submarines (. . .) will compel 
England to peace in a few months. Acknowledge receipt. 
Zimmermann. 
 
Montgomery handed this fragmentary solution to Hall, who stared 
down at the phrases that seemed to jump off the page at him: 
"unrestricted submarine warfare," "war with the U.S.A.," "propose ... an 
alliance." He realized at once that here was a weapon of enormous 
potentiality. He urged Montgomery to hurry the solution, ordered all 
copies except the original message and a single solution burned, and, 
without a word to the Foreign Office, sat down by himself to contemplate 
the situation. 
It was as bleak as that winter's day. The war that everyone had 
expected would last only a few weeks had now dragged into its third year. 
Nor was there any prospect of an end. France had expended half a 
million lives at Verdun  
II 
and only succeeded in restoring the battle line to where it was ten 
months before. England, which had lost 60,000 men at the Somme in a 
single day, struggled to gain a few yards of shell -blasted earth, then fell 
back exhausted . The Hindenburg line remained unbreached. Rumania, a 
new ally, had been quickly overrun , and Russia, the colossus of the east, 
was virtually defeated. The stepped-up U-boat campaign increased the 
economic pressure on the Allies. Worst of all, despite the provocation of 
the Lusitania sinking and despite the tug of ancient common ties, the 
United States, guided by a President who had just won reelection on the 
slogan "He kept us out of war," remained obstinately neutral. 
Things were no better in Germany. Her initial offensive had stalled at 
the Marne and her gray-coated troops had been locked in the futile 
trench slaughter ever since. Civilians were living on potatoes—a result of 
the stranglehold of the British blockade. Fifteen -year-olds were being 
conscripted. Greece and Portugal had recently entered the war against 
her. Like the Allies, she could see no immediate hope for victory. 
Except one. 
Unleash the submarines, the generals cried, and England would soon 
be "gasping in the reeds like a fish ." The blockaders would become the 
blockaded. For months the generals had hammered away on this theme, 
and, as the signs of exhaustion multiplied, they finally prevailed. Foreign 
Minister Zimmermann, who had long opposed the idea, fell in line. But 
this big jolly bachelor, the first to break the Junker barrier in the higher 
regions of the Kaiser's officialdom, perceived that the repeated sinkings of 
American vessels would sooner or later torpedo American neutrality, and 
he bethought himself of a scheme to counter this danger. He proposed a 
military alliance with Mexico, then particularly hostile to the imperialistic 
Norte-americanos as a result of Pershing's punitive expedition into 
Mexican territory. He sweetened the proposition with an offer of money 
and the possibility of support from Japan, standing at America's back, 
and with still more anti- Yankee inducements. 
Unable to deal through the Mexican ambassador, who was in 
Switzerland, Zimmermann sent his proposal to his minister in Mexico, 
Heinrich J. F. von Eckardt, by way of Washington. To ensure that it 
would get there, he routed 
jt two ways, both monitored by Britain. The cruise  of Telconia was 
paying off. 
One way was called the " Swedish Roundabout" by the British. 
Sweden, which was neutral in favor of Germany, had since early in the 
war helped the German Foreign Office get messages past the British 
cable blockade by sending them as her own. British censorship detected 
this practice. When Sweden complained in the summer of 1915 that 
Britain was delaying her messages, Britain informed her that it had 
positive knowledge of the unneutral practice. • The Swedish government 
admitted this and promised that it would no longer send any German 
messages to Washington. It did not. Instead, it sent them to Buenos 
Aires. Here they were transferred from Swedish to German hands and 
then forwarded to Washington. This was a circuitous route of about 
7,000 miles, half of them in flat violation of the prerogatives of a 
nonbelligerent. 
But the cable from Stockholm to South America touched at England. 
Germany feared that British censorship might recognize the German 
codegroups in the Swedish messages and would stop the dispatches. So 
the German Foreign Office disguised the codegroups by enciphering 
them. This was done with Code 13040 in messages to Latin America and 
to Washington. Unfortunately for the Germans, the superencipherment 
did not obliterate all traces of the underlying code, which employed a 
distinctive mixture of 3-, 4-, and 5-digit codegroups. These traces 
aroused the suspicious of the ever-alert Room 40; it resolved the 
superencipherment, and Code 13040 reappeared. Room 40 then looked 
closely at other official Swedish messages. Many of them proved to be 
German as well; concealed under one superencipherment, for example, 
they found Code 0075. But this time England entered no protest. Hall 
perceived that it was more advantageous to listen to what the Germans 
were saying than to stop them from talking. 
The second route that Zimmermann used was of such simplicity, 
perfidy, and barefaced gall that it probably remains unequaled in the 
annals of diplomacy. It had its inception in the pompous mind of Colonel 
Edward M. House, President Wilson's alter ego and a major exponent of 
personal diplomacy. On one of his missions to Europe in 1915, House 
arranged to have coded reports from the embassies cabled directly to 
him, bypassing the State Department. When, on December 27, 1916, 
Ambassador 
Bernstorff discussed a new peace attempt by Wilson with House, he 
pointed out that the chances would be improved if his government could 
communicate directly with Wilson through House. House checked with 
the President. The next day Wilson permitted the German government to 
send messages in its own code between Washington and Berlin under 
American diplomatic auspices—an arrangement that was, at best, 
simpleminded, and that, furthermore, contravened the accepted 
international practice of requiring the messages to be submitted in clear 
for transmission in American code. 
Germany availed herself of this arrangement to make America seal her 
own doom by letters she herself bore. Under the aegis of American 
sovereignty, Zimmermann sent his message striking at that sovereignty. 
It was delivered to the American embassy in Berlin at 3 p.m. January 16. 
It could not go direct to Washington, but had to be sent first to 
Copenhagen—and then to London. Only from there could it go to 
Washington. Consequently Britain seized this copy as well. Room 40 was 
"highly entertained" at the sight of the German code in an American 
cable, but again did not protest. 
With two copies of the same text helping to eliminate garbles, 
Montgomery and de Grey rammed into the cryptogram. De Grey, though 
at 30 the younger of the two, had been in Room 40 the longer. Slightly 
built, rather handsome, with dark hair and brown eyes and chiseled, 
movie-star features , an Eton graduate, he was descended from the 
peerage as the grandson of the fifth Baron Walsingham (no relation to Sir 
Francis Walsingham). He had worked for the prestigious publishing 
house of William Heinemartn for seven years before the war, when he 
joined the Royal Naval Air Service. He came to Room 40 in 1915. 
Montgomery was 45 at the time of his work on the Zimmermann 
telegram. A Liverpool shipowner's son who studied in private schools or 
under tutors in England, France, and Germany, he took a bachelor of 
divinity degree at Presbyterian College, London. But his health prevented 
an active pastorate and he became a member of St. John's College at 
Cambridge University. He specialized in early church history, editing the 
Confessions of St. Augustine for the Cambridge Patristic Series and 
writing a study on the life and thought of the African father. His most 
memorable work, however, was as a translator. It was said of his 
translation of Albert Schweitzer 's The Quest of the Historical  Jesus  in 
1910 that "no German work has ever been rendered into English so 
idiomatically and yet so faithfully." A modest , reticent man, Montgomery 
entered the censor's office in 1916, and later that year moved to Room 
40. 
While in Room 40 his familiarity with Scripture unriddled a problem 
that had baffled most of the other staffers. A Sir Henry Jones had 
received a blank postcard from Turkey addressed to him at 184 King's 
Road, Tighna-bruaich, Scotland. Sir Henry knew that the card was from 
his son, who had been captured by the Turks, but Tighna-bruaich is a 
small village, with no King's Road and so few houses that no number 
would have been needed in any case. The card found its way to Room 40, 
where nobody seemed able to ascertain what Sir Henry's son was trying 
to tell him. Finally Montgomery suggested a reference to chapter 18, 
verse 4, of one of the books of Kings. Second Kings shed no light, but 
First Kings revealed that " Obadiah took a hundred prophets, and hid 
them fifty in a cave, and fed them with bread and water." Montgomery 
interpreted this to mean that Sir Henry's son was safe with other 
prisoners but in need of food—and this proved to be the case. 
But the solution of the Zimmermann telegram required more than a 
flash of inspiration. It demanded the reconstruction of Code 0075, a two-
part code of 10,000 words and phrases numbered from 0000 to 9999 in 
mixed order. Since a code is, in a sense, a gigantic monoalphabetic 
substitution, the establishment of plaintext equivalents is the "only" task 
involved. But where the cryptanalyst of cipher deals with only 26 such 
elements, the cryptanalyst of code must keep his eye on hundreds or 
thousands, whose characteristics, moreover, because of their reduced 
frequency, are much scantier and more diffuse than the sharply defined 
traits of letters. 
Solution usually begins with the identification of the groups meaning 
stop. Groups that recur near the end of telegrams are likely candidates. 
The identification of stop or period is often aided because often only a few 
of the many code equivalents are employed. Code clerks, referring 
frequently to stop, come to memorize one or two of its codegroups; they 
then simply use these groups in encoding instead of hunting up a 
different one in the codebook. 
Indeed, cryptanalysts familiar with a given embassy's messages can 
often tell when a new code clerk has been hired by the sudden 
efflorescence of new equivalents for stop! 
The identification of the stops outlines the structure of the message. 
In English messages, nouns , as the subjects of sentences, will often 
appear directly after stops. In German, where the predicate often comes 
at the end of the sentence, the codegroup immediately preceding a stop 
may be a verb . Other clues come from the stereotyped expressions that 
diplomats so love in their dispatches: "I have the honor to report to Your 
Excellency. ..." Collateral information is of very great value. 
The first tentative identifications are usually written in pencil for easy 
erasing, and such are called "pencil groups." Eventually, further traffic 
confirms them and they become "ink groups." Solution proceeds much 
more rapidly if a code is one-part. If codegroup 1234 represents a word 
beginning with d, then 5678 must represent one farther back in the 
alphabet; this both rules out some guesses and suggests others. 
Sometimes the meaning of a codegroup can be indicated rather precisely 
by its location between two ink groups. This is not possible with a two-
part code, where the code and plain equivalents are matched in an 
absolutely arbitrary fashion. Code 0075 was of this type. It required more 
traffic for its solution than a one-part code, and the identifications came 
more slowly and with greater difficulty. It had been in service on the 
Continent for only half a year—not a very long time for a diplomatic 
code—and portions of many messages remained unreadable. 
As more traffic came in (including now the messages to and from 
Bernstorff), Montgomery and de Grey, working night and day, filled in 
more and more groups, ever more rapidly. On January 28, de Grey 
brought Hall part of Bernstorffs protest against Zimmermann's plan of 
unrestricted submarine warfare, which, to the ambassador's dismay, had 
been announced to him in message No. 157, the first part of the double-
decker. Bernstorff argued vigorously against this plan, for he felt that it 
negated all his efforts to bring about a detente between the two countries 
and that it would drive the United States into the war on the side of the 
Allies. 
And in fact, on February 3 Wilson announced to Congress that he was 
breaking diplomatic relations with Germany, as he had said he would the 
previous April if 
Germany continued its course of submarine warfare. Though he 
added that "only actual overt acts" on Germany's part would make him 
believe that she really would sink neutral vessels on the high seas, it 
must have seemed to the war- weary Allies that now, at last, within a few 
days or a fortnight at most, the United States would enter the war. Day 
by day, they awaited the final inevitable step. 
While waiting, Room 40 continued its work on Code 0075. De Grey 
had taken to Hall Bernstorff's message giving details of his interview with 
Wilson severing relations. Recovered codegroups were substituted into 
the Zimmermann telegram, and on February 5 Hall was able to show a 
more fully solved version of it to Lord Hardinge at the Foreign Office. 
Hall had realized from the first day that Montgomery had brought him 
the first sketchy solution of the Zimmermann telegram that he had in it a 
propaganda weapon of titanic proportions. Exposure of this German plot 
directed against the United States would, in the present circumstances, 
almost certainly compel that nation to declare war on Germany. This was 
an immensely strong argument for showing it to the Americans. But for 
the moment, at least, even stronger considerations militated against it. 
First, Room 40 and its cryptanalytic capabilities was one of Britain's 
darkest secrets. How could she disclose the message without Germany's 
guessing that her codes were being read? Britain might minimize the risk 
by hinting that the plaintext had been stolen, but the danger would still 
remain that Germany would suspect the truth, change her codes, and 
deprive Britain of her most valuable intelligence. In the second place, to 
reveal the message, Britain would have to admit that it had been 
supervising the code telegrams of a neutral: Sweden. It would not require 
much wit for the Americans to surmise that England might also be 
supervising the code telegrams of another neutral: the United States, 
which, like Sweden, was working as a messenger boy for the Germans 
and had, in fact, transmitted this very message. This realization would 
both embarrass and anger the United States and would not conduce to 
pro-Allied feelings. In the third place, the solution was still not complete. 
The missing portions would inevitably raise doubts about the validity of 
the solution and so weaken its impact. Perhaps the British had failed to 
solve a word like "not" that would completely alter the sense, 
the arguments would run. Perhaps the British had not even correctly 
solved the portion that they were offering as evidence of German 
duplicity. Moreover, the gaps would shout "codebreaking," preventing 
any subterfuges about captured codes or a stolen message and exposing 
the very secret Britain sought to conceal. 
But the most powerful argument against disclosure of the German 
plot, with all the attendant difficulties, was that events might make it 
unnecessary. Relations had been severed between Germany and the 
United States. American public opinion seemed to be turning 
increasingly against Germany. Shipping dared not sail ; ports were 
congested; men were laid off; business languished. Bitterness was 
growing. It seemed only a matter of a short while until the declaration of 
war. And so the British continued to wait, and to hope. 
Hall, however, while waiting for events to dictate, did not remain idle. 
His job was only half done if he merely solved the Zimmermann telegram 
without making it ready for use by his government. Consequently, he 
conceived a plan that at one stroke might resolve the three difficulties 
connected with the telegram's exposure, in what still appeared the 
unlikely event that that might be necessary. He reasoned that the 
telegram as received in Mexico would differ in small but significant 
details from the telegram as sent from Berlin. The date would almost 
certainly be different, and probably the serial number as well. The 
preamble addressed to BernstorfF ordering him to forward the message 
would of course be omitted. If Hall could produce the copy from Mexico, 
perhaps the Germans would spot these slight variations and infer that 
the plaintext had been betrayed on the American continent and would 
not change their codes. Other collateral details might confirm a tale of a 
Mexican theft to the Americans. Moreover, Room 40 perhaps knew, from 
its numerous solutions of German messages via the Swedish 
roundabout, that the German mission in Mexico had not used Code 0075 
and probably did not hold it. Bernstorff might then have had to re-
encode the Zimmermann telegram in another code, which Room 40 
might have solved more completely than 0075 and which might therefore 
enable it to fill in the missing portions in its solution. 
On February 5, therefore, Hall began trying to get a copy of the 
Zimmermann telegram as received in Mexico. 
An English agent known only as T obtained from the Mexico City 
telegraph office a copy of the message that Bernstorff had sent to Eckardt 
by Western Union. Soon Hall had it. 
It proved him right in every one of his assumptions. Eckardt did not 
have Code 0075, and so Bernstorff had had to recede the dispatch in one 
that Eckardt did have. This was Code 13040, which was an older and 
simpler code than 0075 and whose superencipherment had led to the 
discovery of the Swedish roundabout. It had been distributed to German 
missions in Central and South America between 1907 and 1909 and to 
Washington, New York, Havana, Port-au-Prince, and La Paz in 1912. Its 
basic repertory contained about 25,000 plaintext elements with a fair 
number of homophones—Bernstorff's telegram alone employed six 
different groups for zu—and proper names took up a huge section of 
75,000 codenumbers. But Code 13040 was a cross between one-pa'rt 
and two-part codes. In the encoding section, blocks of several hundred 
code-numbers in numerical order stood opposite the alphabetized 
plaintext elements, but the blocks themselves were in mixed order. A 
skeleton code, made up from a few groups from Bernstorff's encoding, 
will illustrate this: 
encoding                              decoding 
13605 Februar                    5144 wenigen 
13732 fest                           5161 werden  
13850 fmanzielle                 5275 Anregung 
13918 folgender                  5376 Anwendung 
17142 Frieden                     5454 ar 
17149 Friedenschluss           5569 auf 
17166 fuhrung                    5905 Krieg 17214 Ganz geheim 17388 
Gebeit 
4377 geheim 
4458 Gemeinsame 
The solution of such a hybrid code stands midway in difficulty 
between the two pure types : harder than a one-part code but easier than 
a two-part. The large orderly segments considerably help the 
cryptanalyst, though his guesses are not as delimited as in a one-part 
code. For example, the cryptanalyst could not assume, as he could in a 
one-part solution, that a codegroup for Krieg will be 
higher in number than the codegroup for Februar. But if he knows 
that Februar is 13605 and  finanzielle  is 13850, he will know that the 
codegroup for fest must almost certainly fall somewhere between the two. 
His identifications thus come with greater speed and certainty. 
 
[Codebreakers 114.jpg]
The Zimmermann telegram as re-encoded in Washington into Code 
13040 and forwarded to Mexico 
 
Owing to this weakness, and to the fact that they had had all of the 
war to work on a great volume of messages, the codebreakers of Room 40 
had recovered most of Code 13040's commonly used groups. They could 
consequently read all or nearly all of Bernstorff's message to Eckardt, 
and in those few places where a rare proper name or syllable might have 
been used for the first time, the partial alphabetical arrangement 
afforded a strong check on their guesses. This eliminated the problem of 
having only a partial solution. In addition, it confirmed their almost- 
complete solution of the original Berlin-to-Washington message and 
added a few new values to their reconstruction of Code 0075. 
The cryptanalysts also found the slight changes in heading that Hall 
had foreseen. Bernstorff had deleted the Foreign Office preamble and 
substituted one of his own: "Foreign Office telegraphs January 16: No. 1. 
Most Secret. Decode yourself." He replaced the Berlin-Washington serial 
number with a Washington-Mexico City serial number, which was 3. And 
finally, his message was dated January 19, which, due to the numerous 
steps in the complicated transmission routes, differed from the January 
16 date that the original German text bore. 
Fairly early in February, it seems, Hall' was ready. With a stroke 
bordering on genius, he had done his job. His must stand as one of the 
most subtly dissembling moves in the whole history of espionage. It was 
now possible to give the message to the Americans, should that prove 
necessary, with as little risk as possible to Britain's intelligence sources. 
But though Hall had covered his tracks fairly well, it remained possible 
that the Germans might guess the truth. Events might yet make it 
unnecessary to chance this. So Britain held the message and waited. 
And waited. The days passed. On the Western Front the lifeblood of 
the Empire and of the French republic trickled into the earth. The armies 
shuddered in mortal combat. Still there came no sign that America was 
going to enter the war. Though it seemed that Germany's announcement 
of unrestricted torpedoings of American ships had made, as Bernstorff 
himself had warned in cables read by Room 40, "war unavoidable," the 
American President seemed unable to do what the British thought that 
honor, self-respect, and the whole course of recent actions made 
obligatory. Even Ambassador Page, a long-time friend of the President 
and a wholehearted sympathizer with the Allied cause, was irked enough 
to note in his diary , "The danger is that with all the authority he wants 
(short of a formal declaration of war) the President will again wait, wait, 
wait—till an American liner be torpedoed! Or till an attack is made on 
our coast by a German submarine!" Evidently Wilson was waiting for the 
"overt acts" that he had mentioned in his address to Congress. But 
perhaps Germany would not actually be so rash as to torpedo American 
ships and thereby—Britain thought—cut her own 
I 
throat . More days passed. The Germans did nothing. Tension 
mounted. The situation was, a British diplomat in America reported, 
"much that of a soda-water bottle with the wires cut but the cork 
unexploded." 
It exploded on February 22, 1917. Unable to wait any longer, the 
British gave the cork a push. Hall, with Foreign Office approval if not 
under its orders, showed the Zimmermann telegram to Edward Bell, a 
secretary of the American embassy who maintained liaison with the 
various intelligence offices of the British government. He read an 
astounding tale of German intrigue against his country: 
 
We intend to begin on the first of February unrestricted 
submarine warfare. We shall endeavor in spite of this to keep the 
United States of America neutral. In the event of this not 
succeeding, we make Mexico a proposal of alliance on the following 
basis: 
Make war together, make peace together, generous financial 
support, and an understanding on our part that Mexico is to 
reconquer the lost territory in Texas , New Mexico and Arizona. The 
settlement in detail is left to you. 
You will inform the President [of Mexico] of the above most 
secretly, as soon as the outbreak of war with the United States of 
America is certain and add the suggestion that he should, on his 
own initiative, invite Japan to immediate adherence and at the 
same time mediate between Japan and ourselves. 
Please call the President's attention to the fact that the ruthless  
employment of our submarines now offers the prospect of 
compelling England in a few months to make peace. 
Zimmermann. 
 
Bell did not believe it. The notion that anyone in his right mind would 
consider giving away a chunk of the continental United States was 
simply too preposterous. But Hall convinced him of its authenticity, and 
the two went over to Grosvenor Square. When Page saw the message, he 
realized at once that the entry into war on England's side, which he had 
so single-mindedly pursued and the 
President had so obstinately opposed, was at last delivered into his 
hands. Hall, Bell, Page, and Irwin Laughlin, first secretary of the 
embassy, spent the day trying to decide how best to instill confidence in 
the telegram's genuineness, to minimize incredulity, and to maximize its 
impact. They decided that the British government should officially 
present the telegram to Page, and in his room at the Foreign Office the 
next day Arthur Balfour, now secretary of state for foreign affairs, 
formally communicated it to Page in a moment that Balfour later 
confessed was "as dramatic a moment as I remember in all my life." 
Page worked all night to draft a covering message explaining how the 
telegram was obtained. At 2 a.m. February 24 he cabled, "In about three 
hours I shall send a telegram of great importance to the President and 
Secretary of State," but it was not until 1 p.m. that the Zimmermann 
telegram, with his explanation, was transmitted. He gave the President 
the collection of half- truths that Hall had given him—for Hall naturally 
withheld the deep secret of British cryptanalytic ability, particularly since 
it might start the Americans wondering whether Britain was reading their 
code messages as well: 
 
Early in the war the British government obtained possession of 
a copy of the German cipher code used in the above message and 
have made it their business to obtain copies of Bernstorffs cipher 
telegrams to Mexico, among others, which are sent back to London 
and deciphered here. This accounts for their being able to decipher 
this telegram from the German government to their representative 
in Mexico, and also for the delay from January 19th until now in 
their receiving the information. This system has hitherto been a 
jealously guarded secret and is only divulged to you now by the 
British government in view of the extraordinary circumstances and 
their friendly feeling toward the United States. They earnestly 
request that you keep the source of your information and the 
British government's method of obtaining it profoundly secret, but 
they put no prohibition on the publication of Zimmermann's 
telegram itself. 
 
Page's pilot telegram rattled the Morse sounders at the State 
Department at 9 a.m. Saturday, February 24, but 
the "telegram of great importance" did not arrive until 8:30 that 
evening. Frank L. Polk, counselor of the department and acting secretary 
in the absence of Secretary of State Robert L. Lansing, telephoned to ask 
the President to expect him and carried the four typewritten yellow 
sheets across the street to the White House. Wilson, Polk reported, 
showed "much indignation" on reading it, and wanted to make it public 
at once. But he agreed to Folk's suggestion to await Lansing's return 
from a long weekend. 
On Tuesday, February 27, Lansing came back from White Sulphur  
Springs. Polk told him about the Zimmer -mann telegram and showed 
him an exceptionally long cable of 1,000 codegroups that he had found 
in the State Department files. It had come for Bernstorff in an American 
cablegram of January 17 from Berlin and was, Polk felt, almost certainly 
the coded original. (It was, in fact, the double-decker, which included the 
Zimmermann telegram.) At 11 that morning, Lansing, armed with this, 
discussed the whole situation with the President, who, exclaimed "Good 
Lord!" several times at the outrageous German abuse of the cable 
privileges he had extended them. He consented to Lansing's plan to 
release the telegram through the press, which Lansing felt "would avoid 
any charge of using the document improperly and would attract more 
attention than issuing it openly." Accordingly, at 6 p.m. the next day, E. 
M. Hood of the Associated Press was called to Lansing's home, given the 
message and some background details, and pledged to secrecy on the 
greatest scoop of the war. 
The story broke in eight-column streamers in the morning papers of 
March 1. "Profound sensation," Lansing noted. The nation gasped. In 
Congress, the House orated patriotically and passed by 403 to 13 a bill to 
arm merchant ships. But the Senate, more deliberate, wondered whether 
the whole thing was not just a crude Allied plot. This reaction had been 
foreseen. Lansing had asked Page to "Please endeavor to obtain copy of 
German code from Mr. Balfour," but the British had told him that the 
code was "never used straight, but with a great number of variations 
which are known to only one or two experts here. They can not be spared 
to go to America." This was, of course, another half-truth—the 0075 
message was probably superenciphered (the "variations") but the 13040 
one was not Polk, meanwhile, exerted tremendous pressure on 
Newcomb Carlton, the president of Western Union, and finally 
managed to get a copy of BernstorfFs telegram to Eckardt despite a 
federal law protecting the privacy of. telegrams. Lansing appended this 
codetext to the wire he sent Page at 8 p.m. the day of the expose : 
 
Some members of Congress are attempting to discredit 
Zimmermann message charging that message was furnished to 
this government by one of the belligerents. This government has 
not the slightest doubt as to its authenticity but it would be of the 
greatest service if the British government would permit you or 
someone in the Embassy to personally decode the original message 
which we secured from the telegraph office in Washington, and 
then cable to Department German text. Assure Mr. Balfour that 
the Department hesitated to make this request but feels that this 
course will materially strengthen its position and make it possible 
for the Department to state that it had secured the Zimmermann 
note from our own people. 
 
The message, No. 4494, was received the next day, and by 4 p.m. 
Page cabled back: "Bell took the cipher text of the German messages 
contained in your 4494 of yesterday to the Admiralty and there, himself, 
deciphered it from the German code which is in the Admiralty's 
possession." In fact Bell wrote only a dozen or so plaintext groups before 
letting de Grey do the rest in his neat handwriting. Page then sent the 
German text as decoded by Bell and de Grey. But Lansing and the 
President had already sent up to the Senate a statement that the 
government possessed evidence establishing the telegram as genuine, 
and that no further information could be disclosed. 
Everyone already had his own pet theory of how the United States had 
gotten it. Most popular was the spy story. Most farfetched was that four 
American soldiers had found it on a German agent trying to cross into 
Mexico. Most plausible was that the telegram had been found among 
Bernstorff s effects when his baggage was searched at Halifax after his 
dismissal. Most amusing were the attacks by the British press on the 
inefficiency of their secret service and its inferiority to the American. (At 
least one of these was instigated by Hall himself to throw the theorizers 
off the scent .) 
 
[Codebreakers 150.jpg]
Nigel de Grey transcribes the Code 13040 version of the Zimmermann  telegram   into  
plaintext for  the  skeptical Americans 
Wilhelmstrasse , too, wondered where the leak had occurred. Though 
the message as published in the papers did not carry either BernstorfFs 
heading or his serial number, it did bear the significant date January 19. 
"Please cable in same cipher," the Foreign Office purred at a quivering 
Eckardt, who had already tried to blame Bernstorff for the betrayal, "who 
deciphered cable dispatches 1 [the Zimmermann telegram] and 11 
[ordering Eckardt to negotiate at once for the proposed alliance], how the 
originals and decodes were kept, and, in particular, whether both 
dispatches were kept in the same place." Six days later, it picked up the 
clue that Hall had carefully planted: "Various indications suggest that 
the treachery was committed in Mexico. The greatest caution is 
indicated. Burn all compromising material." 
Eckardt mustered impressive details to exculpate himself: "Both 
dispatches were deciphered, in accordance with my special instructions, 
by [Dr. Arthur von] Magnus [the legation's corpulent secretary]. Both, as 
is the case with everything of a politically secret nature, were kept from 
the knowledge of the chancery officials. . . . The originals in both cases 
were burned by Magnus and the ashes scattered. Both dispatches were 
kept in an absolutely secure steel safe, procured especially for the 
purpose and installed in the chancery building, in Magnus' bedroom, up 
to the time when they were burned." Three days later, he sent in his 
reserves: "Greater caution than is always exercised here would be 
impossible. The text of telegrams which have arrived is read to me at 
night in my dwelling house by Magnus, in a low voice. My servant, who 
does not understand German, sleeps in an annex. . . . Here there can be 
no question of carbon copies or waste paper." The shrieks of hilarity that 
this occasioned Hall, Page, and Room 40 were not heard in Berlin. Its 
last doubts swept away by the low voice, the steel safe, the scattered 
ashes, and the non-German-speaking servant, the Foreign Office 
capitulated. "After your telegram it is hardly conceivable that betrayal 
took place in Mexico. In face of it the indications which point in that 
direction lose their force. No blame rests on either you or Magnus." 
 
[Codebreakers 152.jpg] 
"Exploding in his Hands." Cartoon by  Rollin  Kirby in The [New York] World just after 
the Zimmermann telegram was made public 
 
Meanwhile, the problem of authenticity, which had so troubled the 
Anglo-American officials and stirred uneasy questions in the Senate and 
the press, had been eliminated by Zimmermann himself. Completely 
unexpectedly, he confessed: "I cannot deny it. It is true." Knowledge of 
the plot had been blandly disavowed by the Mexicans, the Japanese, and 
Eckardt, and to this day no one knows why Zimmermann admitted it. 
His acknowledgment buried the last doubts that the story might have 
been a hoax. 
Suddenly, Americans in the middle of the continent who could not get 
excited about the distant poppings of a European war jerked awake in 
the realization that the war was at their border. Texans blinked in 
astonishment: the 
Germans meant to give away their state! The Midwest, unmoved 
because untouched by the submarine issue , imagined a German-
officered army crossing the Rio Grande and swung over to the side of the 
Allies. The Far West blew up like a land mine at the mention of Japan. 
Within a month, public opinion crystallized. Wilson, who three months 
before had said that it would be a "crime against civilization" to lead the 
nation into war, decided that "the right is more precious than peace" and 
went up to Capitol Hill on April 2 to ask Congress to help make the world 
safe for democracy. He cited the Zimmermann telegram in his address: 
"That it [the German government] means to stir up enemies against us 
at our very doors, the intercepted note to the German minister at Mexico 
City is eloquent evidence. We are accepting this challenge of hostile 
purpose. ... I advise that the Congress declare the recent course of the 
Imperial German Government to be in fact nothing less than war against 
the government and people of the United States, that it formally accept 
the status of belligerent which has thus been thrust upon it." 
The Congress did. Soon the Yanks were coming. The fresh strength of 
the young nation poured into the trenches of the Western Front to rescue 
the exhausted Allies. And so it came about that Room 40's solution of an 
enemy message helped propel the United States into the First World War, 
enabling the Allies to win, and into world leadership , with all that that 
has entailed. No other single cryptanalysis has had such enormous 
consequences. Never before or since has so much turned upon the 
solution of a secret message. For those few moments in time, the code-
breakers held history in the palm of their hand. 
9.   A War of Intercepts 
RADIO, envisioned by its inventor as a great humanitarian  
contribution, was seized upon by the generals soon after its birth in 1895 
and impressed as an instrument of war. For it immeasurably magnified 
the chief military advantage of telegraphy: instantaneous and continuous 
control of an 
II 
entire army by a single commander. By eliminating the need for 
physical linkage by wire, radio speeded communication between 
headquarters, joined through the ether units that could not connect by 
wire because of distance, terrain, hostile forces, or rapid movement, 
opened communications with naval and air forces, and eased the 
economic burden of producing immense quantities of wire. But few 
blessings are unmixed. Just as the telegraph had made military 
communications much more effective but had also increased the 
possibility of interception over that of hand-carried dispatches, so radio's 
vast amplification of military communications was accompanied by an 
enormously greater probability of interception. The public, 
omnidirectional nature of radio transmissions, which makes wireless 
communication so easy to establish, makes it equally easy to intercept. It 
was no longer necessary to gain physical access to a telegraph line 
behind the enemy's front to eavesdrop upon his communications. A 
commander had only to sit in his headquarters and tune his radio to the 
enemy's wavelength. Radio thereupon introduced two revolutionary  
factors in the interception of communications: volume and continuity. 
Communications are intercepted, of course, so that they may be 
submitted to cryptanalysis. Now cryptanalysis has a potential that 
cryptography does not. Cryptanalysis can alter the status quo. 
Cryptography can at best conserve it. Cryptanalysis can bring countries 
into war, engender naval battles and win them, compel besieged cities to 
yield, condemn queens to death and exile priestly conspirators from their 
homeland. Cryptanalysis hammers upon the real world. Cryptography 
does not. 
Consequently, the telegraph, which affected only cryptography, had 
had a wholly internal influence upon cryptology. That a hierarchy of 
special systems had arisen to displace the nomenclator interested only 
cryptologists; it did not matter to generals or statesmen. And although 
the telegraph greatly increased the volume of communications, 
wiretapping could produce intercepts only at rare and irregular intervals. 
Cryptanalysis could exercise only transient and haphazard effects. Its 
potential remained largely unfulfilled. Kerckhoffs accurately regarded it 
as an auxiliary to cryptography, a means to the end of perfecting military 
codes and ciphers. Cryptanalysis during the telegraph years was 
interesting but inconsequential, intriguing but academic—an 
I' ideal topic to pass a Victorian tea-time, perhaps, but not 
I  much more. 
; -     The radio, however, turned over to the commander a 
i copy of every enemy cryptogram it conveyed. It furnished a constant 
stream of intercepts. And with these, cryptanaly-sis could bear 
continually upon operations, could be depended upon for information, 
could affect events decisively. The generals and the statesmen took 
notice. This was no longer a polite trifling discussion; this had become a 
weapon, a pursuit entailing all the savagery of warfare and life against 
death. Radio made cryptanalysis an end in itself, elevating it to an 
importance coordinate with that of cryptography, if not superior' to it. 
Radio's impact upon cryptology reverberated in the outside world. 
Wire and wireless thus complemented one another. The telegraph 
created modern cryptography; the radio, modern cryptanalysis. The one 
developed cryptology internally, the other externally. The telegraphy had 
given cryptology shape and content; now the radio carried it out into the 
arena of life. One gave it form; the other, meaning. The radio completed 
the work that the telegraph had begun. And so it was that radio, first 
widely used in the Great War of 1914 to 1918, brought cryptology to 
maturity. 
 
To the right of the imposing stone A.E.F. headquarters building at 
Chaumont stood an undistinguished, single-story barracks of glass and 
concrete. Sometimes called the "Glass House," the caserne housed the 
other half of the American cryptologic effort, the Radio Intelligence 
Section, G.2 A.6. 
Its chief, Major Frank Moorman, 40, a native of Michigan, was a blue-
eyed, brown-haired Regular Army man who had worked his way up 
through the infantry ranks from private. He was a 1915 graduate of the 
Army Signal School and knew enough about cryptanalysis to devise an 
ingenious method for almost automatically determining the letters of a 
Playfair keyword. In France, however, Moorman did not engage in any 
actual cryptanalysis, except perhaps to help out, since his work as head 
of G.2 A.6 was administrative, not operative. As a boss he was well 
regarded by his men for his fairness and blunt honesty. 
G.2 A.6's first real victory in the war of the intercepts came early in 
1918 with the shift of the Germans away from the divisional codes that 
they had long been using—a 
series of codes, differing from unit to unit, whose codewords all began 
with the letters K, R, or u. 
It was at midnight of March 11 that the Germans placed into service 
not merely a new code, but one that, from its numerical codegroups, 
appeared to be of a different breed entirely. The Allies were expecting a 
major German push, and the appearance of this code was considered 
another straw in the wind. Its solution would obviously be of importance 
in giving clues to German activities. Though the British had suggested 
that a superencipherment might be involved, the precise nature of the 
system had to be determined, the superencipherment stripped off, and 
the repertory then built up. This would have imposed much greater 
difficulties than just solving another codebook edition—except for 
American alertness. 
Forty minutes after midnight, the American intercept post at Souilly 
picked up one of the first messages in the new system. Station x2 was 
sending it to station AN: 
00:25 CHi-13 845 422 373 792 240 245 068 652 781 245 659 504 
At 12:52 AN replied: CHI-13 os RGV KZD. Five minutes later x2 sent a 
second message to AN: 
00:25 CHI-14 UYC REM KUL RHI KWZ RLF RNQ KRD RVJ UOB KUU UQX UFQ RQK 
When these appeared on the desk of code cryptanalyst Lieutenant 
Hugo Berthold , he guessed at once what had happened: x2 sends a 13-
group cipher message (cHi-13) in a new system. AN responds with os, a 
well-known service abbreviation for  Ohne Sinn ("message unintelligible"), 
and a reference to cm-13, followed by two groups from the old KRU code. 
Whereupon x2 sends a second message, this time in KRU but with the 
original time group (00:25). The old KRU had been partially solved, and 
Berthold knew that the RGV of the short AN message meant "old." He did 
not know the meaning of KZD, but it seemed likely in view of what 
happened that it meant "Send in code," making the whole phrase "Send 
in old code." Could the Germans have been so stupid as to compromise 
their new code within an hour after putting it into service by sending the 
same message in both the old and the new systems? 
Berthold's blue eyes fairly snapped and the few pale wisps of hair that 
lay against his bald pate almost stood up with excitement as he decoded 
the second x2 message with his reconstructed KRU. It read: 
UYC REM KUL  RHI KWZ RLF RNQ KRD RVJ UOB  KUU 
An   [?]   Bn.    2             h     i      r    sch           w 
UQX   UFQ   RQK 
i      tt     e 
The KWZ and UOB appeared to be nulls, used—almost certainly in 
violation of regulations—as word dividers, and REM probably meant 
Kommandant. When Berthold checked this against the second message, 
he saw at once that it had the same plaintext. The repetitions of the 
plaintext i's and t's, which had been masked by the homophones and the 
lexicon of the KRU code, appeared clearly in the trinumeral message as 
the repeated 245s and 659s. With these four points as anchors, Berthold 
could set up the following equivalencies: 
845 422 373 792 240 245 068 652 781 245 659 659 504 An [?] Bn. 2 
h i r sch w i t t e 
A staff airplane sped his result to the British cryptanalytic bureau, 
and Berthold telegraphed it in a special code-breakers' code to the 
French. It was a Rosetta Stone for a new forward code called the 
Schliisselheft. The three bureaus cooperated closely, but it was largely 
due to a French genius that within two days they had neutralized the 
Schliisselheft superencipherment and dismembered much of the lexicon. 
By March 21, when the expected German blow fell, Allied cryptanalysts 
were reading Schliisselheft messages better than the German code clerks 
themselves. Theoretically no important information was supposed to be 
carried in it, because it was intended only for low-level, . front-line 
communications. But theory succumbed at times of great activity, when 
the information was most desirable, and the trinumeral messages were 
laden with valuable nuggets. "The sending of this one message must 
certainly have cost the lives of thousands of Germans," Moorman said, 
"and conceivably it changed the result of one of the greatest efforts made 
by the German armies." 
It was also in preparation for this Great German onslaught that 
another new cipher made its appearance. This was the ADFGVX system, 
the most famous field cipher in the whole history of cryptology. It was so 
named because only those six letters occurred in its cryptograms, though 
just five were used (no v) when the system sprang into use on March 5, 
1918. 
The war in the West had by then become a stalemate of exhaustion. 
The young recruits who the Kaiser had promised in the glorious summer 
of 1914 would be "home before the leaves fall" had become veterans 
hardened by almost four years of battle—those few who survived. The 
flower of England's youth had perished; in France, a generation had 
climbed out of the trenches and vanished forever. 
During the winter, Germany had come to realize that she would have 
to win in the spring if she were to win at all. The U-boat had failed to 
starve England into submission , and the United States had entered the 
war against her. But the collapse of Russia had freed dozens of German 
divisions for service on the Western Front and, for the first time, 
Germany held a numerical preponderance there. This, however, was only 
until America could transport her strong young forces across the 
Atlantic. It was to be now or never, and the imperial government lashed 
its weary troops and hungry civilians for the supreme effort that was to 
bring final victory. 
It was no less clear to the Allies that Germany planned to launch a 
climactic offensive in the spring. There were many signs—the new cipher 
itself was one. The question was: Where and when would the actual blow 
fall? The German high command, recognizing the incalculable military 
value of surprise, shrouded its plans in the tightest secrecy. Artillery was 
brought up in concealment; feints were flung out here and there along 
the entire front to keep the Allies off balance; the ADFGVX cipher, which 
had reportedly been chosen from among many candidates by a 
conference of German cipher specialists , constituted an element in this 
overall security, as did the new Schliis-selheft. The Allies bent every effort 
and tapped every source of information to find out the time and place of 
the real assault. But one of their most flowing founts—cryptanalysis —
appeared to have dried up. 
When the first ADFGX messages got to Georges Painvin, 
the best cryptanalyst in the Bureau du Chiffre, he stared at them, ran 
a hand through his thick black hair with an air of perplexity, and then 
set to work. The presence of only five letters immediately suggested a 
checkerboard. Without much hope, he tried the messages as simple 
monoalpha-betics; the tests were, as he had expected, negative. He 
discarded a polyalphabetic checkerboard as too cumbersome, and was 
left with the hypothesis that the checkerboard substitution had been 
subjected to a transposition. On this basis he began to work. 
Nothing happened. The traffic was too light for him even to determine 
by frequency counts whether the checkerboard key changed each day, 
and without this basic information he did not dare to amalgamate the 
cryptograms of successive days for a concerted assault. Colonel Francois 
Cartier, head of the Bureau du Chiffre, looked on over his shoulder as he 
braided and unbraided the letters and . mused sadly, "Poor Painvin. This 
time I don't think you'll get it." Painvin, goaded, worked harder than 
before. Meanwhile, Berthold achieved his Schliisselheft entry and 
Painvin, shifting temporarily to that more fruitful field, completed it. But 
the enciphered code, used only for trench communications, provided no 
strategic insights. These would come, if they were to come at all, through 
solution of the ADFGX, which direction-finding showed was carrying 
messages between the higher German headquarters, chiefly those of 
divisions and army corps. Painvin strained even harder. 
At 4.30 a.m. March 21, 6,000 guns suddenly fired upon the Allied line 
at the Somme in the most furious artillery cannonade of the war. Five 
hours later, 62 German divisions rolled forward on a 40-mile front. The 
surprise was complete and its success overwhelming. French and British 
troops reeled back day after day in stunned confusion. The head of 
intelligence at French G.H.Q. came into the cryp-tologic bureau three 
days later and told Major E.-A. Soudart, the replacement for ex-chief 
Marcel Givierge, and Soudart's assistant, Marcel Guitard: "By virtue of 
my job I am the best informed man in France, and at this moment I no 
longer know where the Germans are. If We're captured in an hour, it 
wouldn't surprise me." Within a week the Germans had punched a hole 
38 miles deep in the Allied lines, and it was not until the British and 
French 
troops fell back to Amiens that they collected themselves and halted 
the advance. 
The furious advance was reflected in a dramatic upsurge in radio 
traffic. The first result was disappointment. Pain-vin's frequency counts 
showed that the checkerboard key did change daily; presumably the 
transposition key did also. Solution would therefore require a goodly 
quantity of text from a single day, but until April 1 the interceptions were 
too meager. On that day, the French picked up 18 ADFGX messages 
totaling 512 five-letter groups. Two had been sent in three parts, and 
Painvin noticed on April 4 that the first parts of the two messages had 
identical bits and pieces of text larded in the same order in the 
cryptograms. This oddity could most likely have resulted from both 
cryptograms having identical beginnings transposed accordingly to the 
same key; the identical fragments of text would then represent the 
identical tops of the columns of the transposition tableau. Sectioning the 
cryptograms so that each identical fragment started a new segment 
would yield the columns of the tableau, in the order of their 
transcription. Painvin cut up the cryptograms so that each identical 
fragment started a new segment. These segments constituted the 
columns of the tableau in the order of their transcription. Painvin then 
noticed that some columns were long in both cryptograms, some were 
short in both, and some were long in one and short in the other. The long 
columns must have stood at the left of the transposition tableau. Those 
keynumbers must therefore have been the first in the transposition key. 
Painvin thus made a first approximation to that key. Pursuing this 
reasoning, he distributed the keynumbers in zones within the key. He 
then put columns side by side and counted the resultant letter pairs. 
Most counts were flatfish, displaying no distinctive characteristics. But 
some appeared monoalphabetic in nature—some highs, some mediums, 
many blanks. These counts represented two columns that had stood side 
by side in the original tableau and so contained the digraphic substitutes 
from the checkerboard. In this way Painvin gradually built up the entire 
transposition key. When he had done that, he had only to solve the 
checkerboard substitution as a monoalphabetic to reach the plaintext. 
After 48 hours of incredible labor , Painvin had cracked the first messages 
in the toughest field cipher the world had yet seen. 
His feat shows the cryptanalytic mind at its finest. Pain-vin spotted 
opportunities that many would have missed, and when he worked with 
one, he did not leave it until he had wrung it dry. This technique of 
extracting every drop of information from each phase of solution before 
moving on served well, for the cipher prickles with many defenses. From 
the German point of view, the system was quick and easy, involving only 
two simple steps. Messages were doubled in length, but this 
disadvantage was somewhat offset by the presence of only five different 
letters in the cryptograms, making transmission faster and more 
accurate. The ADFGX letters of the coordinates had been chosen by the 
inventor of the system, Lieutenant Fritz Nebel, because he had found 
them easy to remember when first learning the Morse code. 
By the time Painvin had achieved his first solution, the first German 
offensive had spent its force, and the volume of traffic had diminished. 
After three weeks of work, he managed on April 26 to achieve his second 
solution. Meanwhile the Germans again struck with surprise and forced 
the English back almost to the sea. But Painvin was getting his feet on 
the ground , and the subsequent key recoveries came with increasing 
speed: nine and a half days, two days, and, finally, one day. 
But by then the French had been dealt two unpleasant blows—one 
military, one cryptographic. Ludendorff had again managed to conceal 
the time and place of a major assault. Fifteen of his divisions fell by 
surprise on seven. A gray flood of Germans inundated the French 
positions in the heights of the Chemra-des- Dames and surged forward 
irresistibly until it lapped the banks of the Marne only 30 miles from 
Paris, almost submerging the Allied cause. At the same time, Painvin 
suddenly saw, on June 1, the ADFGX messages complicated by the 
addition of a sixth letter, v. Probably the Germans expanded their 
checkerboard to 6 X 6. But why? For homophones to further blunt the 
frequency clues? Or to insert the ten digits? Painvin did not know. 
"In short," he said, "I had a moment of discouragement. The last two 
keys of the 28th and the 30th of May had been discovered under 
conditions of such rapidity that their exploitation was of the greatest 
usefulness . The offensive and the German advance still continued. It was 
of the greatest importance not to lose [cryptanalytic] contact and 
in my heart I did not want to brusquely shut off this source of 
information to the interested services of the armies, which had become 
accustomed to counting on its latest results." 
He opened his assault on the cryptograms of June 1 at 5 p.m. Three 
messages of that date all bore the same time group (00:05) and had all 
been sent from a transmitter with call-sign GCI. Noticing that a message 
to call-sign DAX had 106 letters and one to call-sign DTD had a similar 
text of 108 letters, he assumed that the two plaintexts were the same 
except for the addition of a single element to the internal address of the 
DTD message. He had only to seek an arrangement of columns that would 
produce such a pair of cryptograms. Within an hour he had found it: 
6 16 7 5 17 2 14 10 15 9 13 1 21 12 4 8 19 3 11 20 18 The solution of 
the checkerboard followed quickly: 
c
     
              
m
     
              
n
j
     
              
5
     
              
P
     
              
e
     
              
The DAX plaintext read: 14 ID XX Gen Kdo ersucht vordere Linie sofort 
drahten XX Gen Kdo 7 ("14th Infantry Division: HQ requests front line 
[situation] by telegram. HQ 7th [Corps]"). The DTD text was identical 
except for its being addressed 216 ID. 
Painvin completed his solution at 7 p.m. on June 2, and sent it at 
once to G.H.Q. By then the French had managed to halt Ludendorff's 
push, but they teetered precariously on the brink of defeat. The Germans 
were shelling Paris from 60 miles away with their long-range guns. The 
great German successes of March and May had driven two vast salients 
into Allied territory. They pointed like daggers at Paris. And the great 
question recurred: Where would Ludendorff strike next? The thin Allied 
lines could not hold against a massive piledriver blow concentrated on a 
single point. If Ludendorff could gain the same surprise that he had so 
successfully achieved in each previous assault, he 
could puncture the Allied defenses, overrun Paris, and perhaps end 
the war. The Allies' only hope of stopping him was to absorb his thrust 
head-on with their reserves. But to do this they had to know where to 
send them. 
The French discussed the possibilities. Would Luden-dorff lunge out 
directly for Paris from the tip of one of his salients despite the danger to 
their flanks? Or would he first flatten out the large dent between those 
bulges and then drive forward from a consolidated position? If the latter, 
where in the huge pocket would he strike? No one knew. 
Ludendorff, meanwhile, was having troubles of his own. German 
military doctrine called for a sudden, intense artillery bombardment to 
paralyze the defenders before the infantry attacked. This saturation 
technique required concentrating thousands of field pieces and tons of 
munitions at the battle-front. At a conference early in June, Ludendorff 
learned that this concentration was running behind the schedule he had 
set for his next assault. His successes had strained his lines of transport, 
and he had been moving his guns and shells only under cover of night to 
preserve the invaluable advantage of surprise. 
And this advantage he had conserved superbly. The hints that drifted 
out to French G.H.Q. about his intentions were multiple, petty, and 
contradictory . Nothing would jell. Gloomy intelligence officers could 
reach no definite conclusions. Another attack was certainly in the offing, 
but unless they could ascertain its location, France might be lost. 
Into this dismal atmosphere on the morning of June 3 burst Guitard 
of the Service du Chiffre, excitedly waving an intercept. One of the G.H.Q. 
cryptanalysts, applying the keys that Painvin had sent there, had just 
read a cryptogram sent at 4:30 a.m., only a few hours earlier: 
CHI-126 FGAXA XAXFF FAFFA AVDFA GAXFX FAAAG DXGGX 
AGXFD XGAGX GAVGX AGXVF VXXAG XFDAX GDAAF DGGAF 
FXGGX XDFAX GXAXV AGXGG DFAGD GXVAX XFXGV FFGGA 
XDGAX ADVGG A 
Direction-finders reported that it had been transmitted by the German 
High Command. The addressee, Die, was known from traffic analysis and 
direction-finding to be the 18th Army's general staff in Remaugies—a 
town situated just above the concavity in the German lines. Its plaintext 
read: Munitionierung beschleunigen Punkt Soweit nicut [error for nichf\ 
eingesehen auch  bei Tag ("Rush munitions Stop Even by day if not seen"). 
Guitard and the intelligence officers recognized at once that the 
ammunition mentioned in the telegram was that intended for the usual 
German pre-assault bombardment, and the location of the addressee of 
the message told them where that attack would come. Jubilantly they 
communicated their information to the operations officers: Ludendorff 
was going to hammer out the dent, and the German sledge would crash 
down onto the French line between Montdidier and Compiegne , a sector  
about 50 miles north of Paris. 
Aerial reconnaissance confirmed the daylight transport of munitions. 
Deserters reported that the onslaught would take place June 7. Foch , in 
supreme command, shifted his reserves into position, thinned out the 
front lines, upon which the brunt of the cannonade would fall, and 
braced his secondary defenses. On the 6th, officers were told that "the 
offensive is imminent." Tension mounted. The 7th passed without enemy 
action, and the 8th: Ludendorff had postponed the attack for two days to 
bring up more guns and munitions because, he said, "thorough 
preparation was essential to success." The French waited tensely but 
with confidence. At midnight on June 9 the front from Montdidier to 
Compiegne erupted in a fierce, pelting hurricane of high-explosive, 
shrapnel, and gas shells. For three hours a German artillery 
concentration that averaged one gun for no more than ten yards of front 
poured a continual stream of fire onto the French positions—and 
Ludendorff's urgent demand for ammunition became clear. But this time, 
for the first time since Ludendorff began his stupendous series of 
triumphs, there was no surprise. Painvin's manna had saved the French. 
A little before dawn 15 German divisions charged forward. The French 
were ready. For five days, fighting seesawed back and forth. Initially the 
Germans took the little villages of Mery and Courcelles, but on June 11, 
General Charles Mangin counterattacked with five divisions and all the 
elan the French could muster. He stopped the German advance cold and 
then swept the gray tide out of the two villages. Again the Germans 
heaved forward in a great effort. They failed with heavy losses . For the 
first time that spring, Ludendorff suspended an operation before it had 
achieved its goal. Mangin, wearing his gold-brocaded kepi , laughed 
beneath the guns of victory. Foch, who realized that other German 
assaults would come and that he would have to defend against them, 
knew at last that he would some day take the offensive. He knew then 
that the war was not lost, and could eventually be won. Within a few 
weeks, the final German thrusts did come, but they had run out of 
steam, and the French parried them. Soon the initiative passed to the 
Allies, bolstered by the Americans, and their powerful counterstrokes 
drove the German armies back and back until the Kaiser, his militaristic 
dreams wrecked, abdicated and fled while his generals signed the 
Armistice at Compiegne. The World War was ended. 
For Painvin, who had lost 33 pounds while simply seated at his desk, 
there was a long leave of convalescence. Afterwards, he engaged in an 
immensely successful business career, becoming president and director 
general of Ugine, the chemical giant of France, president of a phosphate  
company, vice president of a commercial credit firm, administrator of a 
mortgage society, honorary president of the Union of Chemical Industries 
and of the central committee of the electrochemical trade, and president 
of the Chamber of Commerce of Paris. Yet, he said, none of these 
achievements ever gave him the satisfaction that his ADFGVX solutions 
did. They left "an indelible mark on my spirit, and remain for me one of 
the brightest and most outstanding memories of my existence." 
 
The First World War marks the great turning point in the history of 
cryptology. Before, it was a small field; afterwards, it was big. Before, it 
was a science in its youth; afterwards, it had matured. The direct cause 
of this development was the vast increase in radio communications. 
This heavy traffic meant that probably the richest source of 
intelligence flowed in these easily accessible channels. All that was 
necessary was to crack the protective sheath. As cryptanalysis repeatedly 
demonstrated its abilities and worth, it rose from an auxiliary to a 
primary source of information about the foe; its advocates spoke 
regularly in the councils of war. The emergence of cryptanalysis as a 
permanent major element of intelligence was the most striking 
characteristic of cryptology's new maturity. 
Another was the change in cryptanalysis itself. The science at last 
outgrew the mode of operation that had 
1 
dominated it for 400 years. This was chamber analysis, in which a 
single man wrestles with a single cryptogram alone in his room; 
Rossignol epitomizes the genre. As cipher systems grew increasingly 
complex, cryptanalysts relied more and more on special solutions, and so 
they required many more messages for success than the bewigged 
practitioners of chamber analysis would have ever thought necessary. 
A third characteristic of the new maturity was the evolution of fields of 
cryptanalytic specialization. Systems of secret communication had 
ceased to be so few and so homogeneous that a single expert could 
subdue them all. Their multiplicity and heterogeneity, plus the volume of 
traffic in each, bred the specialist . This division of labor is as much a 
sign of maturity in cryptology as it is in a society. 
Still another sign of that maturity was the emotional apprehension of 
the role played by the blunders of inexperienced, indolent, and ignorant 
cryptographic clerks. Cryptologists had had an intellectual awareness of 
this danger at least since 1605, when Francis Bacon wrote that "in 
regards of the rawness and unskillfulnesse of the handes, through which 
they passe , the greatest Matters, are many times carryed in the weakest 
Cyphars." But it was not until cipher key after cipher key, and code after 
code, had been betrayed by needless mistakes or stupidities or outright 
rule violations that the magnitude of the problem was borne in upon 
them. The problem had swollen to such proportions because so large a 
volume of messages had to be handled by so many untrained men—
against whom were pitted the best brains of the enemy. The experts 
realized that to eliminate these is to strengthen cryptographic security 
more effectively than by introducing the most ingenious cipher. The great 
practical lesson of World War I cryptology was the necessity of infusing 
an iron discipline in the cryptographic personnel. 
All these developments, however, resulted essentially from the 
interreaction between cryptology and the outside world; they were 
externally oriented. World War I originated no developments that were 
internally oriented, as, for example, was the emergence of the field 
cipher. On the contrary, two of the most central activities—the actual 
cryptographic operations, which were performed by hand, and the 
techniques of solution, which were brute frequency analysis—had 
exhausted their usefulness. Manual systems sagged under message 
loads for which 
they were never designed. Not a few cryptographic clerks dreamed of 
machines that would lift the onerous burden from their shoulders. In a 
sense, the codes that became so popular might be regarded as a 
rudimentary form of mechanical device that does the work for the 
encoder: the phrases are prepared and equated with their code 
equivalents in advance, and the encoder has but to pick out the ones he 
wants. But the trench codes were to the printing cipher machines of later 
years as the taxis of the Marne were to the armored troop -carriers of 
Panzer columns. 
At the same time, the classic principles of frequency analysis had 
been stretched to their utmost. They were applied with great subtlety, as 
in Painvin's solving the ADFGVX transposition. But no new principles had 
been evolved, and the old ones had barely coped with such concepts as 
fractionation. 
In these two internal matters, which lie at the core of cryptology, 
World War I marked not the beginning but an end, had reaped not 
fulfillment but barrenness. So viable had the science become, however, 
that this very vacuum, this want, held promise. 
 
10. Two  Americans 
 
THE MOST FAMOUS CRYPTOLOGIST in history owes his fame less to what he 
did than to what he said—and to the sensational way in which he said it. 
And this was most perfectly in character, for Herbert Osborne Yardley 
was perhaps the most engaging, articulate, and technicolored personality 
in the business. 
He was born April 13, 1889, in Worthington, Indiana , and grew up in 
that little Midwestern town during the tranquil, sunlit years that 
preceded the First World War. A popular youngster, he was president of 
his high-school class, editor of the school paper, and captain of the 
football team, and though only an average student, he had a flair for 
mathematics. From 16 on he frequented the poker tables of the local 
saloons, learning the game that was to be a passion of his life. He had 
wanted to become a criminal 
I 
lawyer, but instead landed at 23 as a $900-a-year code clerk in the 
State Department. 
It was a case of purest serendipity, for the man and the subject were 
ideally matched. His romantic mind thrilled to the stream of history that 
daily poured through his hands in the form of ambassadorial dispatches, 
and cryp-tology fired his imagination. He had heard vague tales of 
cryptanalysts who could pry into secrets of state, and when a 500-word 
message from Colonel House passed over the wires to President Wilson 
one night, Yardley, with characteristic audacity, determined to see 
whether he could solve what must be the most difficult of American 
codes. He astonished himself by solving it in a few hours.* His success 
cemented his attachment to cryptanalysis, and he followed this 
demonstration of the low estate of high-level cryptography with a 100-
page memorandum on the solution of American diplomatic codes. While 
absorbed in possible solutions for a proposed new coding method, he 
diagnosed what has ever since been known among cryptol-ogists as the 
"Yardley symptom": "It was the first thing I thought of when I awakened, 
the last when I fell asleep." 
Soon after the American declaration of war in April of 1917, he sold 
the idea of a cryptologic service to the War Department. He succeeded 
partly because the need was genuine, partly because he himself was an 
exceedingly convincing young man. Yardley had proven his cryptanalytic 
ability, and moreover had done well enough in his regular duties to have 
won raises to $1,400 in 43 months. Major Ralph H. Van Deman, later to 
be known as the Father of American Intelligence, commissioned the thin, 
balding 27-year-old as a lieutenant and set him up as the head of the 
newly created cryptologic section of the Military Intelligence Division, MI-
8. 
*The President and his advisor were then using two main systems. 
One was external—a superencipherment applied to the five-digit 
numerical groups of what probably was a State Department code. The 
first digit was enciphered by one of two alternate letters; the two pairs by 
a vowel-consonant combination. Thus, in one edition of the 
superencipherment, 40606 became FEDED, 40699, KEDIR, and so on. The 
other was internal—a jargon code of such less-than-Stygian incognitos as 
MASS for the Secretary of War, NEPTUNE for the Secretary of the Navy, 
BLUEFIELDS for William C. Redfield, Secretary of Commerce,  ALLEY  for 
Franklin K. Lane, Secretary of the Interior , and MANSION for David F. 
Houston, Secretary of Agriculture. Yard-ley does not specify which he 
solved. 
Like Topsy, MI-8 just grew. First to arrive, to take charge of the 
instruction subsection for training A.E.F. cryptanalysts, was Dr. John M. 
Manly, a 52-year-old philologist who headed the Department of English 
at the University of Chicago and was later president of the Modern 
Language Association; a longtime hobbyist in cryptology, he was to 
become Yardley's chief assistant and one of his best cryptanalysts. Manly 
brought with him a bevy of Ph.D.'s clanking with Phi Beta Kappa keys, 
mostly from the University of Chicago. 
The instruction subsection did its teaching at the Army War College. 
It advanced far enough to offer as Problem 20 "General Principles of 
attack on enciphered code when the book is known but the system of 
encipherment unknown." Another subsection popped into being for code 
and cipher compilation; it produced a military intelligence code, two 
geographical codes for combat information from France, and a casualty 
code, which was never used. Soon a communications subsection was 
handling close to 50,000 words a week. As the organization expanded, it 
shifted to ever-larger quarters. Beginning in the balcony overhanging the 
library of the War College, MI-8 moved to the Colonial, an apartment  
house at 15th and M Streets barely ready for occupancy, and then to a 
building on the site of what is now the Capitol Theatre on F Street, all in 
Washington. For security, its offices were always on the top floor. 
Growth continued apace. An intercepted letter in a German shorthand 
instigated a shorthand subsection that soon could read missives in more 
than 30 systems, most commonly Gabelsberger, Schrey, Stolze-Schrey, 
Marti, Brock -away, Duployee, Sloan-Duployan, and Orillana. A blank 
piece -ef paper discovered in the shoe heel of a woman suspected of 
working with German espionage in Mexico turned out to bear a message 
in invisible ink. Fortunately, it proved one of the simpler kinds, which 
can be developed by heat . But it sparked the establishment of a secret-
ink subsection whose expert chemists could detect writing in an invisible 
ink disguised as a perfume with an actual odor and with only one part in 
10,000 of solid matter. 
The Germans later replaced inks in so bulky and conspicuous a form 
as liquids with chemicals that were impregnated into scarves, socks, and 
other garments. They had only to be dipped in water to create the writing 
fluid. These miracles of the test tube, called F and P inks by the 
I 
British chemists who taught the Americans much of what they knew, 
were so precisely formulated that they would react with only one other 
chemical to form a visible compound. 
Eventually, the Allied chemists discovered a reagent that brought out 
secret writing in any kind of ink, even clear water. Crystals of iodine, 
heated gently, sublimated into fumes of a beautiful violet hue that settled 
more densely in those fibers of paper that had been disturbed by any 
kind of wetting action, thus tracing the pen's course. The Germans 
replied by writing in a sympathetic ink and then moistening the entire 
sheet. The Allies struck back with a chemical streak test that would 
show whether the paper surface had been dampened. This was almost as 
incriminating as actual development of a secret-ink letter, for who but a 
spy would wet a letter? The seesaw battle between the chemists of 
Germany, traditionally world leaders in that science, and those of the 
Allies reached a stalemate when both sides discovered the general 
reagent—one that would develop any secret ink at any time, even on 
moistened paper. Formulas differ slightly, but all use a mixture of iodine, 
potassium iodide, glycerine, and water, dabbed on with cotton. The liquid  
concentrates in the more disturbed fibers and reveals the writing. By the 
time this general reagent appeared, MI-8's secret-ink subsection was 
testing 2,000 letters a week for invisible writing and had discovered 50 of 
major importance. Among them were letters that led to the capture of 
Maria de Victoria, a beautiful German spy who was planning to import 
high explosives for sabotage inside the hollow figures of saints and the 
Virgin Mary! 
MI-8 also solved cryptograms. It read diplomatic telegrams of 
Argentina , Brazil , Chile , Costa Rica , Cuba , Germany, Mexico, Spain, and 
Panama. The Spanish-language texts constituted the bulk of its 
cryptanalytic work. The censorship office sent over intercepted cipher 
letters; most of these turned out to be merely personal notes in very 
simple systems, though some of the love letters were so torrid that 
Yardley said, "It rather worried me to see husbands and wives trust their 
illicit correspondence to such unsafe methods." 
Perhaps the most important of the MI-8 solutions was the one that 
largely resulted in the conviction of the only German spy condemned to 
death in the United States dur- 
ing World War I. This was Lothar Witzke, alias Pablo Waberski, who 
was suspected of setting off the Black Tom explosion. He was captured in 
January, 1918, by an American agent, who found in his baggage in the 
Central Hotel in Nogales, Mexico, a cipher letter dated January 15. It did 
not reach MI-8 until spring, and then it kicked about for a few more 
months while several men there tried and failed to solve it. Finally Manly 
took it up. 
This quiet scholar, who never married and whose quiet, simple 
manner contrasted so sharply with his chief's, was to become one of the 
world's leading authorities on Chaucer . He and his collaborator, Edith 
Rickert, labored for 14 years to produce their monumental eight-volume 
work, The Text of the Canterbury  Tales, in which, by a tedious collation of 
scribal errors and variant readings in more than 80 manuscripts of the 
medieval masterpiece, they reconstructed a text that is as close to the 
poet 's own original as the extant evidence allows. The cast of mind that 
can thus sort out, retain, and then organize innumerable details into a 
cohesive whole was just what was needed for the Gothic complexity of 
the 424-letter Witzke cryptogram. In a three-day marathon of 
cryptanalysis, Manly, aided by Miss Rickert, perceived the pattern of this 
12-step official transposition cipher, with its multiple horizontal shiftings 
of three- and four-letter plaintext groups ripped apart by a final vertical 
transcription. He drew forth a message from Heinrich von Eckardt, the 
luckless German minister in Mexico whose very involvement with a 
cryptogram seemed to mean its cryptanalysis,* to the German consular 
authorities: 
"The bearer of this is a subject of the Empire who travels as a Russian 
under the name of Pablo Waberski. He is a German secret agent. Please 
furnish him on request protection and assistance; also advance him on 
demand up to 1,000 pesos of Mexican gold and send his code telegrams 
to this embassy as official consular dispatches." When Manly read this to 
a military commission of colonels and generals who were trying Witzke 
on spy charges in a hushed courtroom at Fort Sam Houston, 
*In addition to this and the Zimmermann telegram, two messages to 
the diplomat from his home office, encoded in the English-French half of 
Clifton's  Nouveau Dictionnaire Frangals, which had replaced the betrayed 
Cipher 13040, were solved by MI-8. They disclosed Germany trying to 
bribe Mexico to remain neutral. 
San Antonio, the effect was condemnatory. The handsome young spy 
was sentenced to death. Wilson later commuted it to life imprisonment, 
however, and Witzke was released in 1923. 
In August of 1918, Yardley sailed for Europe to learn as much as he 
could from America's allies. He obtained entrance to Great Britain's M.I. 
l(b) after demonstrating his abilities and there studied British methods 
for the solution of different codes and ciphers. The doors of Room 40 
remained resolutely locked against him as against everyone else, though 
Hall did give him a German naval code and a neutral nation's diplomatic 
codes. In Paris that fall, Yardley met Painvin, who gave him a desk in his 
office and invited him to his home many evenings. But he never gained 
access to the French Foreign Ministry crypt-analytic bureau. 
He remained in Paris after the Armistice to head the cryptologic 
bureau of the American delegation to the Peace Conference. At first there 
was a tremendous rush to get organized, but then the pressure eased, 
and Yardley and helpers Lieutenants J. Rives Childs of G.2 A.6 and 
Frederick Livesey, who had been sent over from MI-8, enjoyed the life of 
playboy cryptologists. A practical soul , Yardley saw no need for the three 
officers assigned to the bureau to be present at once, and so a rotation of 
duties was arranged that permitted them to spend most of their time at 
the international cocktail parties and dancings that were then the rage of 
Paris. 
When it ended, as it had to, Yardley, viewing with distaste a return to 
the State Department code room, and burning with evangelical fervor 
over America's need for cryptanalysis, exercised his potent salesmanship 
on the State and War departments. He won the concurrence of Frank L. 
Polk, the acting Secretary of State; then, on May 16, 1919, he submitted 
to the Chief of Staff a plan for a "permanent organization for code and 
cipher investigation and attack." Three days later the Chief of Staff 
approved it, and Polk brown-penciled an "O.K." and his initials on it. The 
plan envisioned joint financial support by the two departments at about 
$100,000 a year, but actual expenditures never reached that sum. The 
State Department's contribution of $40,000, which began on July 15, 
1919, could not be legally expended within the District of Columbia, and 
so Yardley soon found himself 
moving the nucleus of a staff (largely recruited from MI-8) and the 
necessary paraphernalia—language statistics, maps, newspaper clipping, 
dictionaries—to New York City. 
By October 1 the organization that was to become known as the 
American Black Chamber was ensconced in the former town house of T. 
Suffern Tailer, a New York society man and political leader , at 3 East 
38th Street. It stayed there little more than a year, however, before 
moving to new quarters in a four-story brownstone at 141 East 37th 
Street, just east of Lexington Avenue. It occupied half of the ornate, 
divided structure, whose high ceilings did little to relieve the 
claustrophobic construction of its twelve-foot- wide rooms. Yardley's 
apartment was on the top floor. All external connection with the 
government was cut. Rent, heat, office supplies, light, Yardley's salary of 
$7,500 a year, and the salaries of his staff were paid from secret funds. 
Though the office was a branch of the Military Intelligence Division, War 
Department payments did not begin until June 30, 1921. 
One of the organization's first assignments was to solve the codes of 
Japan, with whom friction had been growing. Yardley, in an access of 
enthusiasm, promised the solution or his resignation within the year. He 
regretted his impetuousness as soon as he plunged into the task, for he 
almost foundered in the Oriental intricacies of Japanese plaintext, to say 
nothing of codetext. After some preliminary study, assisted by Livesey, 
who had a great aptitude for languages, he ascertained that the 
Japanese employed a watered-down form of their ideographic writing 
called "kata kana" for telegraphic and—presumably— cryptologic 
communication, which was transmitted in Latin letters. Kata kana 
consists of about 73 syllables, each with a sign of its own which had 
been given a roman equivalent, and when Yardley had his typists compile 
frequency tables for the twenty-five plain-language kata kana telegrams 
he had, he discovered that this script obeyed rules of frequency just like 
any other. Specifically, the kana n, the only nonsyllabic kana, was most 
common, appearing often at the end of words, followed by i, no, o, ni, shi, 
wa, ru, and to, in that order. The list of most common syllables and 
words began with ari and continued with aritashi, daijin, denpoo, gai, 
gyoo, and so on. At the end of about four months, the typists had 
prepared elaborate 
I 
statistics ot frequency and contact for about 10,000 kana. He then set 
them to work dividing the ten-letter groups of the Japanese code 
telegrams into pairs of letters and drawing up similar frequency and 
contact data for these pairs. He himself went through the approximately 
100 code telegrams underlining with colored pencils all repetitions of 
four letters or more. But despite the most intensive scrutiny and study, 
no solution was forthcoming. Livesey's linguistic abilities had meanwhile 
brought him a fair acquaintance with Japanese. He found in a bilingual 
dictionary that he had bought for 75 cents that the word owari meant 
"conclusion." Could it be the plaintext of certain codegroups found 
frequently at the end of telegrams? The hypothesis, involving only three 
kana, proved barren. He examined the plain-language telegrams and 
pointed out probable words with conspicuous patterns to Yardley. Two of 
these, which played a vital role in the solution, were "Airurando do-
kuritsu" (" Ireland independence"), with the repeated do, and "Doitsu" 
("Germany"), which used three of the same kana in a different order. This 
was a good clue, but it alone was not the answer. Night after night 
Yardley would climb the stairs to his apartment, weary, hopeless, 
discouraged, and fall into bed, only to wake up excitedly a few hours 
later with a brilliant idea—which invariably turned out to be just another 
blind alley. 
 
By now [he wrote] I had worked so long with these code telegrams 
that every telegram, every line, even every code word was indelibly 
printed in my brain. I could lie awake in bed and in the darkness 
make my investigations—trial and error, trial and error, over and over 
again. 
Finally one night I awakened at midnight, for I had retired early, 
and out of the darkness came the conviction that a certain series of 
two-letter codewords absolutely must equal Airurando (Ireland). Then 
other words danced before me in rapid succession: dokuritsu 
(independence), Doitsu (Germany) , owari (stop). At last the great 
discovery! My heart stood still, and I dared not move. Was I dreaming? 
Was I awake? Was I losing my mind? A solution? At last—and after all 
these months! 
I slipped out of bed and in my eagerness, for I knew I was awake 
now, I almost fell down the stairs. 
With trembling fingers I spun the dial and opened the safe. I 
grabbed my file of papers and rapidly began to make notes. 
 
These promptly proved his intuitions correct. The repetitions of RE for 
do, BO for tsu, OK for ri, and UB for i in his equivalences confirmed it: 
WI UB PO MO IL KB    RE OS OK BO    RE UB BO    AS FT OK 
a   i  ru ra   n  do       do ku  ri tsu      do   i  tsu        o  wa ri 
For an hour Yardley filled in these and other identifications and then, 
convinced that the opening wedge had been driven, went upstairs, awoke 
his wife, and went out to get drunk. Actually, considerably more work 
had to be done before the Black Chamber could read anything 
approaching sentences. Much of this was done by Livesey, who achieved 
an important secondary breakthrough when he identified the Japanese 
plaintext jooin ("Senate") and jooyakuan ("draft treaty "). 
Yardley encountered unexpected difficulties in finding a translator for 
the exotic language, but finally located a kindly, bewhiskered missionary. 
He looked jokingly incongruous in the Black Chamber, but he enabled 
Yardley to send the first translations of Japanese telegrams to 
Washington in February of 1920. He quit after six months when he 
finally realized the espionage nature of the work, but by then Livesey had 
accomplished the almost unheard-of feat of learning Japanese in that 
time. 
Yardley called the first code "Ja," the "J" for Japanese, the "a" a serial 
for the first solution. From 1919 to the spring of 1920 the Japanese 
introduced eleven different codes, having employed a Polish expert, 
Captain Kowalef-sky, to revise then" cryptologic systems. Kowalefsky 
taught the Japanese how to bi-, tri-, and tetrasect their messages: to 
divide them into two, three, or four parts, shuffle the parts, and then 
encipher them in transposed order to bury stereotyped beginnings and 
endings. Some of the codes contained 25,000 code groups. 
During the summer of 1921, the Black Chamber solved telegram 813 
of July 5 from the Japanese ambassador in London to Tokyo. It 
contained the first hints of a conference for naval disarmament—an idea 
that powerfully gripped the imagination of a war-weary world. Another 
indication came when Japan suddenly introduced a new 
code, the YU, for their most secret messages. On solution, it was 
dubbed "Jp"—the sixteenth solved since Yardley's original break. 
A few months before the November opening of the disarmament 
conference in Washington, daily courier service was set up between the 
Black Chamber and the State Department. An official grinningly 
remarked that State's upper echelons were delighted with the cryptan-
alysts' work and read the solutions every morning with their orange juice 
and coffee . The conference sought to limit the tonnage of capital ships, 
and as negotiations were proceeding toward its chief result—the Five-
Power Treaty that accorded tonnages in certain ratios to the United 
States, Britain, France, Italy, and Japan—Yardley's team was reading the 
secret instructions of the negotiators. "The Black Chamber, bolted, 
hidden, guarded, sees all, hears all," he wrote later, rather 
melodramatically. "Though the blinds are drawn and the windows heavily 
curtained, its far-seeking eyes penetrate the secret conference chambers 
at Washington, Tokyo, London, Paris, Geneva, Rome. Its sensitive ears 
catch the faintest whisperings in the foreign capitals of the world." 
Each nation naturally tried to obtain the most favorable tonnage ratio  
for itself; the most aggressive in its efforts was Japan, which even then 
was dreaming expansionist dreams in Asia but feared to offend the 
United States. At the height of the conference, when Japan was 
demanding a ratio of 10 to 7 with the United States and Great Britain, 
the Black Chamber read what Yardley later called the most important 
telegram it ever solved. 
"It is necessary to avoid any clash with Great Britain and America, 
particularly America, in regard to the armament limitation question," the 
Japanese Foreign Office cabled its ambassador in Washington on 
November 28. "You will to the utmost maintain a middle attitude and 
redouble your efforts to carry out our policy. In case of inevitable 
necessity you will work to establish your second proposal of 10 to 6.5. If, 
in spite of your utmost efforts, it becomes necessary in view of the 
situation and in the interests of general policy to fall back on your 
proposal No. 3, you will endeavor to limit the power of concentration and 
maneuver of the Pacific by a guarantee to reduce or at least to maintain 
the status quo of Pacific defenses and to make an adequate reservation 
which will 
make clear that [this is] our intention in agreeing to a 10 to 6 ratio. No 
4 is to be avoided as far as possible." 
Each 0.5 in the ratio meant 50,000 tons of capital ships, or about a 
battle ship and a half. With the information in this message telling the 
American negotiators that Japan would yield if pressed, all they had to 
do was press. This Secretary of State Charles Evans Hughes did, and on 
December 10 Japan capitulated, instructing its negotiator, in a cable 
read by the Black Chamber, that "there is nothing to do but accept the 
ratio proposed by the United States." As signed, the Five-Power Treaty 
allotted capital ships to the United States, Great Britain, Japan, France, 
and Italy in the ratio of 10:10:6:3.3:3.3. It was considerably less than 
Japan had hoped for. Hughes sent Yardley a letter of commendation. 
During the conference, the Black Chamber had turned out more than 
5,000 solutions and translations. Yardley nearly suffered a nervous 
breakdown, and in February went to Arizona for four months to recover 
his health. Several of his assistants had already had trouble in this 
regard. One babbled incoherently; a girl dreamed of chasing around the 
bedroom a bulldog that, when caught, had "code" written on its side; 
another could lighten the enormous sack of pebbles that she carried in a 
recurring nightmare only by finding a stone along a lonely beach that 
exactly matched one of her pebbles, which she could then cast into the 
sea. All three resigned. 
Yardley's appropriation had been severely cut in 1924, and half the 
staff had to be let go, reducing the force to about a dozen. Despite this, 
Yardley said, the Black Chamber managed to solve, from 1917 to 1929, 
more than 45,000 telegrams, involving the codes of Argentina, Brazil, 
Chile, China, Costa Rica, Cuba, England, France, Germany, Japan, 
Liberia , Mexico, Nicaragua , Panama, Peru , San Salvador , Santo Domingo  
(later the Dominican Republic) the Soviet Union, and Spain and made 
preliminary analyses of many other codes, including those of the Vatican. 
Suddenly it all ended. Yardley, who had been obtaining the code 
telegrams of foreign governments through the cooperation of the 
presidents of the Western Union Telegraph Company and the Postal 
Telegraph Company, was encountering increasing resistance from them. 
Herbert Hoover had just been inaugurated, and Yardley resolved 
I 
to settle the matter with the new administration once and for all. He 
decided on the bold stroke of drawing up "a memorandum to be 
presented directly to the President, outlining the history and activities of 
the Black Chamber, and the necessary steps that must be taken if the 
Government had hoped to take full advantage of the skill of its 
cryptographers." He waited to see which way the wind was blowing before 
making his move—and found that it was not with him. Yardley went to a 
speakeasy to listen to Hoover's first speech as President and sensed, in 
the high ethical strictures that Hoover expressed, the doom of the Black 
Chamber. 
He was right, though its actual closing came from elsewhere. After 
Henry L. Stimson, Hoover's Secretary of State, had been in office the few 
months that Yardley thought would be necessary for him to have lost 
some of his innocence in wrestling with the hardheaded realities of 
diplomacy, the Black Chamber sent him the solution of an important 
series of messages. But Stimson was different from previous Secretaries 
of State, on whom this tactic had always worked. He was shocked to 
learn of the existence of the Black Chamber, and totally disapproved of it. 
He regarded it as a low, snooping activity, a sneaking, spying, keyhole-
peering kind of dirty business, a violation of the principle of mutual trust 
upon which he conducted both his personal affairs and his foreign 
policy. All of this it is, and Stimson rejected the view that such means 
justified even patriotic ends. He held to the conviction that his country 
should do what is right, and, as he said later, "Gentlemen do not read 
each other's mail." In an act of pure moral courage, Stimson, affirming 
principle over expediency, withdrew all State Department funds from the 
support of the Black Chamber.* Since these constituted its major 
income, their loss shuttered the office. Hoover's speech had warned 
Yardley that an appeal would be fruitless. There was nothing to do but 
close up shop . An unexpended $6,666.66 and the organization's files 
reverted to 
*In 1940, as Secretary of War, he had to reverse himself and accept 
the cryptanalyses of MAGIC. But the international situation then was 
totally different. "In 1929," he himself has written, in the third person, 
"the world was striving with good will for lasting peace, and in this effort 
all the nations were parties. Stimson, as Secretary of State, was dealing 
as a gentleman with the gentlemen sent as ambassadors and ministers 
from friendly nations. ..." In 1940, Europe was at war, and the United 
States was on the verge . 
the Signal Corps, where William Friedman had charge of cryptology. 
The staff quickly dispersed (none went to the Army), and when the books 
were closed on October 31, 1929, the American Black Chamber had 
perished. It had cost the State Department $230,404 and the War 
Department $98,808.49—just under a third of a million dollars for a 
decade of cryptanalyis. 
 
Yardley, whose job experience had been rather specialized, could not 
find work, and he went back home to Worthington. The Depression  
sucked him dry. By August of 1930, he had had to give up an apartment 
house and a one-eighth interest in a real estate corporation; indeed, he 
complained that he had to sell nearly everything he owned "for less than 
nothing." A few months later he was toying with the idea of writing the 
story of the Black Chamber to make some money to feed his wife and 
their son, Jack. When his old MI-8 friend, Manly, with whom he had 
been in contact all during the 1920's, had to turn down his request for a 
$2,500 loan at the end of January, 1931, Yardley, in desperation, sat 
down to write what was to be the most famous book on cryptology ever 
published. He described the composition of it in a letter to Manly in the 
spring of 1931: 
 
I hadn't done any real work for so long that I told Bye, my 
agent, and the Sat Eve Post that I would need some one else to 
write the stuff. I showed a few things to Bye and Costain, the latter 
editor of POST, and both told me to go to work myself. I sat for days 
before a typewriter, helpless. Oh, I pecked away a bit, and 
gradually under the encouragement of Bye I got a bit of confidence. 
Then Bobbs Merrill advanced me $1000 on outline. Then there was 
a call to rush the book. I began to work in shifts, working a few 
hours, sleeping a few hours, going out of my room only to buy 
some eggs, bread, coffee and cans of tomatoe juice. Jesus, the stuff 
I turned out. Sometimes only a thousand words, but often as many 
as 10,000 a day. As the chapters appeared I took them to Bye who 
read them and offered criticism. Anyway I completed the book and 
boiled down parts of it for the articles all in 7 weeks. 
 
The Bobbs-Merrill Company, of Indianapolis, published the 375-page 
book on June 1, but parts of it had already appeared in three articles at 
two-week intervals in The Saturday Evening Post, the leading magazine of 
the day, which thought so highly of them that it used the first of the 
series to lead its April 4 issue. Yardley was a superb storyteller, and his 
narrative skill did not desert him on paper. Largely owing to this and to 
his vigorous and pungent style, the book itself, The American Black 
Chamber, was an immediate success, and it instantly fixed itself in 
popular lore as the epitome of books on cryptology. Even today, it is 
invariably mentioned in any cocktail-party discussion of the subject, and 
copies remain in demand among secondhand book dealers. Reviews of it 
were unanimously good. Critic W. A. Roberts , in a commendatory review, 
summed up the prevailing opinion: "I think it the most sensational 
contribution to the secret history of the war, as well as the immediate 
post-war period, Which has yet been written by an American. Its 
deliberate indiscretions exceed any to be found in the recent memoirs of 
European secret agents." Reporters hastened to governmental bureaus to 
inquire whether it was all true. The State Department, with masterfully 
diplomatic double-talk, was "disposed to discredit" Yardley's statements. 
At the War Department, officials lied straightforwardly and said that no 
such organization had been in existence in the past four years. 
Because of these "deliberate indiscretions," The American Black 
Chamber sold 17,931 copies, unprecedented for a book dealing with 
cryptology, and a highly respectable figure even today. The English 
edition, entitled Secret Service in America, sold 5,480 more. The book was 
published in French, in Swedish, and in an unauthorized Chinese 
version, but it was in Japan, as might be expected, that sales  
skyrocketed. On a per- capita basis, Japanese sales of 33,119 copies were 
almost four times better than in the United States, where it stirred a 
tremendous furor. On November 5, Ambassador W. Cameron Forbes 
reported to the State Department, which had asked "to be kept fully 
informed" about the Yardley agitation, that "The 'Black Chamber' 
evidently made a great impression in Japan. I often hear reference made 
to it in conversation with various classes of Japanese. According to the 
publishers of the Japanese edition, more than 40,000 copies 
have been sold. It remains a best seller at the present time." Contrary 
to some published reports, however, it did not cause the government to 
fall (Would that books on cryp-tology were that powerful!), nor Japan to 
lodge protests with the United States or repudiate the Five-Power Treaty 
three years later. It did cause Japan to start treating American naval 
officers there to study the language with suspicion. It did impress itself 
so indelibly on the Japanese conscience that, when Shigenori Togo 
became foreign minister ten years later, he recalled the episode and 
checked to see whether Japanese communications were then secure. And 
it contributed to anti-American and antiwhite feeling in Japan. 
Consequently, when Stanley K. Hornbeck, a Far Eastern expert in the 
Department of State, heard that Yardley had written a new book, entitled 
"Japanese Diplomatic Secrets," revealing many Japanese telegrams sent 
during the 1922 naval disarmament conference, he wrote in a 
memorandum of September 12, 1932: "I cannot too strongly urge that, in 
view of the state of excitement which apparently prevails in Japanese 
public opinion now, characterized by fear of or enmity toward the United 
States, every possible effort should be made to prevent the appearance of 
this book. Its appearance would contribute substantially to the amount  
of explosive material which seems to be piling up in Japan." Apparently 
as a result of this, United States marshals seized the manuscript on 
February 20, 1933, at the offices of The Macmillan Company, to whom 
Yardley had submitted it after Bobbs-Merrill had declined it, on the 
grounds that it violated a statute prohibiting agents of the United States 
government from appropriating secret documents. 
He tried writing again, but his imagination seemed to need fact to 
work on, and his adventure novels, The Red Sun of Nippon and The 
Blonde Countess, lacked the excitement of his rather fictionalized 
nonfiction . Metro-Goldwyn-Mayer, however, found the beautiful woman 
spy, the secret codes, and the infallible cryptologist of The Blonde 
Countess eminently suitable for its purposes. A problem was that no 
redblooded movie hero would settle for a dull desk job like codebreaking, 
but the film company fixed that up by destroying the fabric of Yardley's 
tale and making the hero an unwilling intellectual who wanted only to 
serve in the trenches overseas. The result was Rendez- 
vous, starring William Powell , Rosalind Russell , Binnie Barnes, Cesar 
Romero , and Lionel Atwill. Yardley was retained by MGM on a generous 
contract as technical advisor and became friendly with Powell. The film 
premiered at New York's Capitol Theatre on October 25, 1935. The New 
York Times reviewed it as a "lively and amusing melodrama." 
In 1938, after a brief and unsuccessful fling at real-estate speculation 
in Queens, New York, Yardley was hired by Chiang Kai-shek at about 
$10,000 a year to solve the messages of the Japanese armies then 
invading China. In Chungking, he at first passed himself off as an 
exporter of hides, but no one in the small and tight-knit foreign colony  
there was fooled for very long. He seems to have enjoyed some success in 
solving the Japanese ciphers, which appear to have been columnar 
transposition of the kana symbols. 
By then he was changing. He was basically an attractive personality 
who enjoyed simple masculine pleasures. He would rise at dawn to go 
duckhunting, shot a good enough game of golf to have won the Greene 
County (Indiana) championship in 1932, and played poker with a 
compulsive intensity wherever and whenever he could. He regaled his 
companions with a flood of amusing stories, told with the wit and gusto 
of a natural raconteur. He was the very opposite of stuffy, and did not 
hesitate to admit that he knew his way around in a Chinese whorehouse. 
He kept a Chinese and a German mistress* and once organized a virtual 
Oriental orgy for a young correspondent, later nationally famous, on the 
ground that it was necessary for him to be blooded as a man. He enjoyed 
the loyalty and friendship of a great many people, though not everybody 
liked him. Emily Hahn, in her China to Me, said bluntly that she did not, 
calling him "an American with a loud manner of talking." His original 
enterprise, which had enabled him to create MI-8 and the Black 
Chamber, had turned to opportunism with the publication of his book, 
and then had soured to cynicism under the widespread disgust that 
followed that violation of confidence, and under the realization that he 
had traded his soul for a few thousand dollars. 
He returned from China in 1940, and, after a brief at- 
*At different times. 
tempt to be a restaurateur in Washington, went to Canada to set up a 
cryptanalytic bureau which dealt largely with spy ciphers. He was 
reportedly forced out under pressure either from Stimson, then Secretary 
of War, or from the British, though the Canadians did not want to part 
with him. From 1941 to the end of the war he served as an enforcement 
officer in the food division of the Office of Price Administration. His 
popular The Education of a Poker Player , in which he offered an informal 
course of instruction in the game, appeared in 1957. On August 7, 1958, 
he died of a stroke at his home in Silver Spring, Maryland, and was 
buried with military honors in Arlington National Cemetery. 
The obituaries called him "the father of American cryptography." They 
were wrong, but they demonstrated the deep impression that Yardley's 
writing had made on the American consciousness . With all its faults and 
falsehoods, his book had captured the imagination of the public and 
inspired untold numbers of amateurs to become interested in cryptology. 
To the extent that the impact of their fresh ideas enriched American 
cryptology, the credit must go to him. 
 
While Herbert Yardley may be the best known cryptologist, 
uncontestably the greatest is William Frederick Friedman. Unlike his 
contemporary, his eminence is due most emphatically to what he did. 
Indeed, two more dissimilar men in a single field can scarcely be 
imagined. Where Yardley was Rabelaisian, outgoing, superficial, free and 
easy with the details of a good story, and ever ready for the main chance, 
Friedman tended toward introversion, depth of study, personal security, 
timidity, dedication, and accuracy, nicety, and validity of work. Despite 
the relative drabness of these personal traits—or perhaps because of 
them, Friedman's theoretical contributions and his practical attainments 
exceed those of any other cryptologist. Yardley's career was like an 
amazing skyrocket that explodes in fantastic patterns against the 
heavens. Friedman's was like the sun. 
He was born Wolfe Friedman on September 24, 1891 , in Kishinev, 
Russia, the oldest son and second child of Frederick and Rosa Friedman. 
His father, a Rumanian who spoke eight languages and worked as an 
interpreter for the Russian Post Office, emigrated to America in 1892, at 
II 
which time his son's name was changed to William. The family settled 
in Pittsburgh, where his father managed a sewing machine agency. 
William graduated in 1909 as one of the ten honor students in a class of 
300 at Pittsburgh Central High School; he then went to work as chief 
clerk in the Erie City Iron Works, a firm that sold steam engines . About 
that time the back-to-the-farm movement called to city boys, and in the 
fall of 1910, Friedman and three friends enrolled in Michigan 
Agricultural College, whose chief attraction was that it was tuition-free. 
But Friedman soon discovered that farming held little interest for him. 
He was an inventive young fellow who liked to fix things and had written 
some science fiction for his high-school paper; he was rapidly coming to 
the conclusion that he liked science. At the end of the term he learned 
that tuition was also free in a scientific field allied to agriculture—
genetics—at one of the Ivy League universities , Cornell . He borrowed 
train fare and arrived in Ithaca, New York, in February, 1911, where he 
got a job waiting on tables. After commencement in February of 1914, he 
attended graduate school, managing to fall in love twice, once with a 
brunette, once with the blonde daughter of a movie-house owner . While 
he was there, a wealthy textile merchant, George Fabyan, who 
maintained laboratories in acoustics, chemistry, genetics, and cryp-
tology (to try to prove that Bacon wrote Shakespeare 's plays ) on his 500-
acre estate, Riverbank, at Geneva, Illinois, decided that he needed a 
geneticist to improve the grains and livestock on his farm. He applied to 
Cornell for a "would-be-er," not an "as-is-er," and hired Friedman, to 
begin June 1, 1915. 
Fabyan was a man of no formal education but of intelligence and 
energy. He had a great desire to be "somebody," and that desire 
motivated his subsidizing the Baconian studies: proof of this 
revolutionary thesis would cover its patron as well as its actual 
discoverers with glory. He himself read little, but he absorbed enough 
from those around him to make his talk on almost any subject sound 
impressive—at least superficially. He was autocratic, never allowing his 
staff to disagree with him, but otherwise not unpleasant so long as 
employees recognized that he was boss. A cardinal article of faith with 
him was that a well-executed sales campaign could put across almost 
anything. 
Friedman did some genetics work for him, but, because he was handy 
with a camera , he helped the cryptologists who were looking for Bacon's 
cipher signatures in Shakespeare by making photographic enlargements 
of the Elizabethan printing that figured in the work. The Department of 
Ciphers of the Riverbank Laboratories consisted of 14 or 15 high-school 
and college graduates who assigned the individual letters in these 
Elizabethan texts to one or the other of two fonts of type as part of the 
Baconian search. Fabyan gave them their living plus a salary of about 
$50 a month. The staff was fed and housed in Engledew and Hoover 
Cottages, the cipher laboratories taking up the first floor of Engledew. 
The young woman who collated the work of many of the other staff 
members was Elizebeth Smith. She had been , born August 26, 1892, in 
Huntington , Indiana, the youngest of the nine children of John M. Smith, 
a dairyman, banker, and county Republican committeeman, and his 
wife, Sopha, who spelled her daughter's Christian name witb an e 
instead of an a in the middle because she was not going to have anyone 
calling her child "Eliza." After completing high school in Huntington, 
Elizebeth attended Wooster College briefly but was graduated from 
Hillsdale College in Michigan where she had majored in English. While 
working at the Newberry Library in Chicago, she was recruited by 
Fabyan and began work there in 1916. 
Neither she nor Friedman had given any particular previous thought 
to cryptology, but they began to get personally interested in the work. It 
is yet another of the ironies of cryptologic history that the interest of two 
foremost cryptologists was aroused by a false doctrine—a doctrine, 
moreover, against which they later were to wage a lifetime battle. For at 
table at the Riverbank cottages they heard gaudy tales of lusty 
Elizabethan life, of the not-so-Virgin Queen, of courtiers' intrigues and 
the secret histories of the great names of English history—all actually 
invalid decipherments of Shakespeare's plays tending to prove that 
Bacon had written them, related by the gentle, upright, but self-deluded 
woman who had "deciphered" them, Mrs. Elizabeth Wells Gallup . These 
stories stirred Friedman's dormant interest; he began to do some of the 
cryptology, and inevitably its puissant magic seeped like the fume of 
poppies into his mind and spirit and intoxi- 
caiea mm. "When it came to the cryptology," he recalled years later, 
"something in me found an outlet ." 
An understatement. He soon found himself head of the Department of 
Ciphers as well as the Department of Genetics at Riverbank. The 
attraction he felt for cryptology was reinforced by the attraction he felt for 
a cryptologist: the quick-witted and sprightly Miss Smith. In May of 1917 
they were married and started the most famous husband-and-wife team 
in the history of cryptology. 
America had declared war a month before, and River -bank, which had 
the only going cryptologic concern in the country, began getting, on an 
informal basis, cryptograms for solution from various government 
bureaus. Probably the most important were messages to and from a ring 
of 125 Hindus who, with German aid, were taking advantage of 
England's preoccupation in Europe to strike for Indian independence. 
The intercepts were given to Friedman for solution, and he quickly solved 
the number cipher used in cablegrams to Berlin. The letters of the 
plaintext and of the keyword were transformed into digits by means of a 
4 X 7 checkerboard with a normal alphabet; the key digits were then 
added to those of the plaintext to form the ciphertext. One key was 
LAMP. Each agent had his own key, but Friedman had no trouble in 
solving them. Nor was he stumped by a system usually regarded by 
amateurs as the ne plus ultra of cryptographic security: a book cipher. 
It came to him in the form of a seven-page typewritten letter. The 
writer, Heramba Lai Gupta, had enciphered only the important words, 
leaving large patches of clear-text as valuable clues; he had also repeated 
the equivalents for many letters instead of seeking new ones and had 
employed neighboring letters in a single line, thus enabling Friedman to 
reconstruct the words of the keytext as a check upon and aid to the 
solution. For example, Friedman guessed from context that 83-1-2 83-1-
11 83-1-25 83-1-1 83-1-8 83-1-13 83-1-18 83-1-3 83-1-1 83-1-6 83-1-3 
83-1-6 meant revolution in, with the 83 the page, the 1 the line on that 
page, and the third number the letter in that line. (It is interesting to 
note how the third group sticks out as the equivalent for a low-frequency 
letter by being so far back in the line.) This gave him OKI . . N . L . . E . u . . 
as the start of the key line, and this in turn probably let him guess that 
the line started with original or originally. 
 
[Codebreakers 187.jpg]
 
How the Hindus worked the book cipher that William Friedman solved 
 
He would then have known that 83-1-4 in the very next word was the 
equivalent for g in  Bengal . By taking full advantage of such clues he built 
up the entire plaintext without ever knowing what was later 
II 
discovered—that the key book was Price Collier's Germany and the 
Germans, a scholarly work published in New York in 1913. 
The Hindus were prosecuted for trying to purchase the uprising's 
arms in the United States and to ship them from the West Coast. At the 
mass trials in Chicago and San Francisco, Friedman gave evidence that 
in effect convicted the conspirators out of their own mouths. The San 
Francisco proceeding witnessed one of the most dramatic scenes ever to 
occur in an American courtroom when one defendant rose, fired two 
shots from a revolver to assassinate a compatriot who was testifying for 
the government, and was himself killed by a marshal shooting over the 
heads of the crowd. In an anticlimax, a jury later found most of the 
defendants guilty. 
A few months after these Hindu solutions, the British submitted five 
short messages to Riverbank for tests. They had been enciphered by a 
cipher device invented by J. St. Vincent Pletts of M.I. l(b), the British War 
Office cryptanalytic bureau. The machine, to serve in the field, shifted its 
cipher alphabet irregularly by means of gears. So highly did the British 
regard it that one argument advanced against its adoption was that if the 
Germans captured one and adopted it, the Allies would no longer be able 
to solve enemy messages! Friedman, however, at once recovered the 
keyword CIPHER to one of the mixed alphabets. But he could not seem 
to get anywhere with the other keyword and, stymied, he resorted to a bit 
of psychological cryptanalysis. He turned to the new Mrs. Friedman, and 
asked her to make her mind a blank. 
"Now," he went on, "I want you to tell me the first word that comes 
into your mind when I say a word." He paused. "Cipher," he said. 
"Machine," she replied. 
It turned out to be the very key desired. Three hours after Friedman 
received the cryptograms, their plaintexts were being cabled to London. 
(The first one read, in a phrase dear to proud inventors, This cipher is 
absolutely undecipherable.) Needless to say, it ended consideration of the 
Pletts device for Allied use. 
In addition to this cryptanalytical work, Friedman did most of the 
teaching of a class of Army officers sent in the fall of 1917 to Riverbank's 
Department of Ciphers to learn cryptology. For instruction in these 
courses, he 
turned out a series of technical monographs. He completed seven 
before he went overseas to o.2 A.6 in the spring of 1918 and wrote an 
eighth on his return. Known collectively as the Riverbank Publications, 
they rise up like a landmark in the history of cryptology. Nearly all of 
them broke new ground, and mastery of the information they first set 
forth is still regarded as the prerequisite for a higher cryptologic 
education. 
Riverbank Publication No. 22, written in 1920 when Friedman was 
28, must be regarded as the most important single publication in 
cryptology. It took the science into a new world. Entitled The Index of 
Coincidence and Its Applications in Cryptography, it described the 
solution of two complicated cipher systems. Friedman, however, was less 
interested in proving their vulnerability than he was in using them as a 
vehicle for new methods of cryptanalysis. 
In it, Friedman devised two new techniques. One was brilliant. It 
permitted him to reconstruct a primary cipher alphabet without having 
to guess at a single plaintext letter. But the other was profound. For the 
first time in cryptology, Friedman treated a frequency distribution as an 
entity, as a curve whose several points were causally related, not as just 
a collection of individual letters that happen to stand in a certain order 
for noncausal (historical) reasons, and to this curve he applied statistical 
concepts. The results can only be described as Promethean , for 
Friedman's stroke of genius inspired the numerous, varied, and vital 
statistical tools that are indispensable to the cryptology of today. 
Before Friedman, cryptology eked out an existence as a study unto 
itself, as an isolated phenomenon, neither borrowing from nor 
contributing to other bodies of knowledge. Frequency counts, linguistic 
characteristics, Kasiski examinations—all were peculiar and particular to 
cryptology. It dwelt a recluse in the world of science. Friedman led 
cryptology out of this lonely wilderness and into the broad rich domain of 
statistics. He connected cryptology to mathematics. The sense of 
expanding horizons must have resembled that felt by chemists when 
Friedrich Wohler synthesized urea, demonstrating that life processes 
operate under well-known chemical laws and are therefore subject to 
experimentation and control, and leading to today's vast strides in 
biochemistry. When Friedman subsumed 
cryptanalysis under statistics, he likewise flung wide the door to an 
armamentarium to which cryptology had never before had access. Its 
weapons—measures of central tendency and dispersion, of fit and 
skewness , of probability and sampling and significance—were ideally 
fashioned to deal with the statistical behavior of letters and words. 
Cryptanalysts, seizing them with alacrity, have wielded them with 
notable success ever since. 
This is why Friedman has said, in looking back over his career, that 
The Index of Coincidence was his greatest single creation. It alone would 
have won him his reputation. But in fact it was only the beginning. 
 
He and Mrs. Friedman quit Riverbank near the end of 1920. The 
situation had become intolerable. Fabyan had lured him back after the 
war with raises and promises of absolute freedom to prove or disprove 
the existence of ciphers in Shakespeare. But he had squelched every 
attempt to do so and had embarrassed Friedman into apparently 
acquiescent silence at lantern-slide lectures on the subject. On January 
1, 1921, Friedman began a six-month contract with the Signal Corps to 
devise cryptosystems. When it expired, he was taken on the civil-service 
payroll of the War Department at $4,500 a year. 
One of his first assignments was to teach a course in military codes 
and ciphers at the Signal School, then at Camp Alfred Vail, New Jersey. 
For this he wrote a textbook that, for the first time, imposed order upon 
the chaos of cipher systems and their terminology. These had sprouted 
in a bewildering variety, and writers treated each as individual and 
special cases. Friedman sorted them out on the basis of structure 
instead of aspect, and so logical and useful was this classification that it 
has become standard. He modeled his nomenclature on his categories, so 
that the names he minted have the great merit of making the relations 
between the various genera of ciphers evident on sight. An example is the 
complementary pair " mono -alphabet" and "polyalphabet"; the French 
were still calling polyalphabetic systems by the almost obfuscatory 
"double substitution," which tells absolutely nothing at all about the 
system. Friedman's most important coinage was the word 
"cryptanalysis," which he devised in 1920 to clear up a chronic source of 
confusion in cryptology—the ambiguity of the verb "decipher," then used 
to mean both 
authorized and unauthorized reductions of a cryptogram to plaintext. 
He titled his book Elements of Cryptanalysis, and the term has so 
prospered that today it circulates in general conversation and print. 
While the book's main contribution is its taxonomy, each of its 143 
pages of text manifests the author's concern for always making clear to 
the reader why things happen as they do. As a result, the student 
understands principles and phenomena, and the lessons stick. Partly 
because of this pedagogical effectiveness, partly because of its 
substantive values, Friedman's book, issued by the Chief Signal Officer 
in May of 1923 as Training Pamphlet No. 3, has guided the development 
of all American cryptology since then. 
At the start of 1922, Friedman became Chief Crypt-analyst of the 
Signal Corps in charge of the Code and Cipher Compilation Section, 
Research and Development Division, Office of the Chief Signal Officer. To 
help him carry on the work of the office he had a single clerk-typist—a 
cauliflower-eared ex-prizefighter. Because Yard-ley's Black Chamber was 
doing the cryptanalysis for the War Department, Friedman's functions 
were nominally cryptographic. He installed the M-94—the Jefferson 
wheel cipher—as the Army's field cipher. Paradoxically, however, his job 
involved a great deal of cryptanalysis. He was continually testing the new 
systems of cryptography urged on the Army as "absolutely 
indecipherable" by zealous amateurs. 
Most difficult of these was the machine with five wired codewheels—
rotors—invented by Edward H. Hebern, whose principle became the most 
widely used in high-level cryptography during World War II. The device 
produces a cipher of hideous nightmare complexity. Friedman sorted it 
out and reconstructed the wiring of the rotors. This work was of the 
utmost importance, for it laid the foundations for the PURPLE machine 
solution and for today's many solutions of modem rotor machines. The 
technique was far in advance of its time. So far as is known, not another 
cryptanalyst on the globe could duplicate it—and none did, apparently, 
for more than two decades. With this solution of Friedman's, world 
leadership in cryptology passed to America. 
Meanwhile, the Army had been studying its divided cryptologic 
operation and, shortly before tie State Depart - 
ment withdrew support from Yardley's bureau, hac decided to 
integrate both cryptographic and cryptanaJytic functions in the Signal 
Corps. The closing of the Black Chamber eased the transition, and on 
May 10, 1929, cryptologic responsibility devolved upon the Chief Signal 
Officer. To better meet these new responsibilities, the Signal Corps 
established a Signal Intelligence Service in its War Plans and Training 
Division, with Friedman as director. Its officially stated mission was to 
prepare the Army's codes and ciphers, to intercept and solve enemy 
communications in war, and in peace to do the training and research —a 
vague enough term—necessary to become immediately operational at the 
outbreak of war. To carry out these duties, Friedman hired three junior 
cryptanalysts, all in their early twenties, at $2,000 a year—the first of the 
second generation of American cryptologists. They were Frank Rowlett, a 
Virginian, and Solomon Kullback "and Abraham Sinkov, close college 
friends who had taught together in New York City high schools before 
coming to Washington and who both received their Ph.D.'s in 
mathematics a few years later. It was the beginning of an expanion that 
led to the PURPLE solution, the triumphs of World War II, and the massive 
cryptologic organization of today. At his death on November 2, 1969, he 
was widely regarded as the greatest cryptologist that science had ever 
seen. 
By this time the Navy, too, had its cryptologic section. Like the 
Army's, it had evolved gradually. 
Naval participation in the 1917 war was too limited for cryptanalytic 
development, but interest was stimulated. Accordingly, in January of 
1924, Lieutenant Laurance F. Safford was ordered to set up a radio 
intelligence organization in the Code and Signal Section. When he left for 
sea duty two years later, a small, highly secret organization was 
functioning in Room 2646 of the "temporary" Navy Department building 
on Constitution Avenue. Lieutenant Ellis M. Zacharias , who trained 
seven months in 1926 with the cryptanalytic organization, told what it 
was like: 
 
My days were spent in study and work among people with 
whom security had become second nature. Hours went by without 
any of us saying a word, just sitting in front of piles of indexed 
sheets on which a mumbo jumbo of figures or letters was displayed 
in chaotic 
disorder , trying to solve the puzzle bit by bit like fitting together 
the pieces of a jigsaw puzzle. We were just a few then in Room 
2646, young people who gave ourselves to cryptography with the 
same ascetic j;'       devotion with which young men enter a 
monastery. It ';•:      was known to everyone that the secrecy of our 
work '!      would prevent the ordinary recognition accorded to other 
accomplishments. It was then that I first learned that intelligence 
work, like virtue, is its own reward. 
 
On completion of his apprenticeship, Zacharias took charge of an 
intercept post on the fourth floor of the American consulate in Shanghai 
to learn as much as he could from Japanese naval messages. Safford 
returned to cryptology in June, 1929, and, except for a four-year tour at 
sea from 1932 to 1936, stayed with the science from then on. He built up 
the communications intelligence organization into what later became OP-
20-G and, by adding improvements of his own to Edward Hebern's rotor 
mechanisms, gradually developed cipher machines suitable for the 
Navy's requirements of speed, reliability, and security. His contributions 
to cryptanalytics were minor, since his talents lay more in the 
administrative and mechanical fields. But he is the father of the Navy's 
present cryptologic organization. 
 
11.  Secrecy for  Sale 
 
 
ON A MORNING in December of 1917, a rather handsome young man of 27 
hurried through the colonaded lobby of the American Telephone & 
Telegraph Company at 195 Broadway in downtown Manhattan. He rode  
the elevator up to the 17th floor, where he worked in the telegraph 
section of the company's development and research department. This 
section, composed of some of the brightest engineers in the company, 
was concentrating on the newest development in telegraphy, the printing 
telegraph or teletypewriter. 
Gilbert S.  Vernam was—if things were  as  usual—a little late that 
morning. He nearly always was, and, his 
boss said, "It used to burn me up to see him come sneaking in and 
slink into his seat." The yearbook of his alma mater, Worcester 
Polytechnic Institute, had wondered "what would happen to Tech if 'Tau' 
should accidently get to class on time in the morning." 
A native of Brooklyn , Vernam was graduated from the Massachusetts 
college, where he had been president of the Wkeless Association and had 
been elected to Tau Beta Pi, the engineering honorary society, in 1914, 
after having spent a year working. He immediately joined A. T. & T. and, 
a year later, married a Brooklyn girl, Alline L. Eno. They had one child. 
Vernam was a clever young man— one of the stories about him has him 
stretched on his couch each evening wondering aloud, "What can I invent  
now?" He had the rare type of mind that can visualize an electrical circuit 
and put it down on paper without having to try it out with wires. He did 
so well in the telegraph section that its head, Ralzemond D. Parker , 
assigned him to a special secrecy project . And late though he may have 
been that winter morning, Vernam had brought a bright idea to work 
with him. Quiet and unassuming, though with a droll sense of humor , he 
probably put forth his suggestion with diffidence, but his co- workers on 
the secrecy project saw at once that he had something. 
The project had begun during the summer, a few months after war 
had been declared, when Parker directed some of the telegraph section 
members to investigate the security of the printing telegraph. Would its 
very newness, the fact that the enemy might not have developed such 
means, guard its messages? The secrecy group soon found that it did 
not. The fluctuations of the current could be recorded by an oscillograph 
and the messages read with ease. Even multiplexing—sending several 
messages simultaneously in both directions over a single wire—offered 
no real security. The engineers resolved the oscillograph undulation into 
its constituent curves and read the eight individual messages. The group 
discussed altering connections inside the printing telegraph mechanism. 
This would have the effect of enciphering one letter into another in a 
monoalphabetic substitution. The engineers realized that this offered no 
real secrecy but, stymied, did not pursue the matter until Vernam 
bounded in with his idea. 
It was based upon the Baudot code, the Morse code of 
the teletypewriter. In this code, named for its French inventor, J.M.E. 
Baudot, each character is allotted five units, or pulses. Each unit 
consists of either an electrical current or its absence in a given time. 
There are, consequently, 32 different combinations of marks and spaces, 
and a combination is assigned to each character—26 for the letters and 
one each for the six "stunts" (space between words, shift up to numbers 
and punctuation marks, shift back down to letters, return type-carriage 
to left side of paper, feed paper up a line, and idle). Through an electrical 
arrangement involving rotating commutators, the proper sequence of 
pulses is sent out when a character's key is struck on the keyboard. For 
example, a is mark mark space space space, i is space mark mark space 
space and the figure shift is mark mark space mark mark. At the 
receiving end, the incoming pulses energize electromagnets that, in 
combination, select the proper character and print it. In the punched 
paper tape which is frequently used to run teletypewriters, marks are 
represented by holes and spaces by leaving the tape intact . To read the 
tape, metal fingers push through the holes to make contact and thereby 
send pulses; where there is a space, the paper keeps the fingers from 
completing the circuit. 
Vernam suggested punching a tape of key characters and 
electromechanically adding its pulses to those of the plaintext 
characters, the "sum" to constitute the ciphertext. The addition would 
have to be reversible so that the receiver could subtract the key pulses 
from the cipher pulses and get the plaintext. Vernam decided upon this 
rule: If the key and the plaintext pulses are both marks or both spaces, 
the ciphertext pulse will be a space. If the key pulse is a space, and the 
plaintext a mark, or vice versa—if, in other words, the two are different—
the ciphertext pulse will be a mark. The four possibilities are these: 
plaintext        key        ciphertext 
mark    +    mark    =    space 
mark    +    space    =    mark 
space    +    mark    =    mark 
space    +    space    =    space 
Decipherment is unambiguous. For example, with cipher-text mark 
and key space only mark is possible for the 
plaintext. The whole system may be set out in a single, compact table. 
Using the convenient notation of 1 for mark and 0 for space, the rule 
would be tabulated as follows: 
plaintext 1    0 
key 
0 
0    1 
1    0 
ciphertext 
In accordance with this rule, Vernam combined the five pulses of the 
plaintext character with the five of the key character to obtain the five 
pulses of the ciphertext character. Thus, if the plaintext is a, or 11000, 
and the key is 10011, which happens to be B, the encipherment is this: 
plaintext key 
ciphertext 
11000 10011 
0101 1 
At the receiving end, the key pulses are applied one by one to the 
successive ciphertext pulses; the rule determines the plaintext pulses. 
With cipher pulses 10100, and the key pulses 00110, the plaintext would 
be: 
ciphertext          10100 
key                   00110 
plaintext           1    0    0    1    0, or d. 
To combine the pulses electrically Vernam devised an arrangement of 
magnets, relays, and bus- bars . Since encipherment and decipherment 
were reciprocal, the same arrangement served for both. He fed the pulses 
into this device from two tape readers—one for a keytape, the other for 
the plaintext tape. The mechanism closed a circuit, resulting in a mark, 
when the two incoming pulses were different, and opened a circuit, 
resulting in a space, when they were the same. This output of marks and 
spaces could be transmitted just like an ordinary teletypewriter message 
to the receiver. Here the Vernam apparatus sub- 
tracted out the key pulses, which were supplied by an identical 
keytape, and recreated the original plaintext pulses. These it would 
channel into a teletypewriter receiver, which would print out the 
plaintext, just like a news ticker in a city room. 
That was the beauty of it. No longer did men have to encipher or 
decipher a message in a separate step (though they still had to prepare 
keytapes, insert them in the apparatus, etc., since doing away with these 
would dispense with secrecy altogether). Plaintext went in and plaintext 
came out, while anyone intercepting the message between the two 
endpoints would pick up nothing but a meaningless sequence of marks 
and spaces. Messages were enciphered, transmitted, received, and 
deciphered in a single operation—exactly as fast as a message in plain 
English. The advantage was not the mechanical enciphering and printing 
of the message. That had been accomplished as far back as the early 
1870s by two Frenchmen, fimile Vinay and Joseph Gaussin—though not 
with the speed and ease of a typewriter keyboard. Rather it was the 
assimilation of encipherment into the overall communication process. 
Vernam created what came to be called "on-line encipherment" (because 
it was done directly on the open telegraph circuit) to distinguish it from 
the old, separate, off-line encipherment. He freed a fundamental process 
in cryptography from the shackles of time and error. He eliminated a 
human being—the cipher clerk—from the chain of communication. His 
great contribution was to bring to cryptography the automation that had 
benefited mankind so much in so many fields of endeavor. 
These values were immediately recognized, and Ver-nam's idea 
quickly kicked up a flurry of activity. He put it down on paper in a sketch 
dated December 17. A.T. & T. notified the Navy, with which it had 
worked closely in a communications demonstration the previous year, 
and on February 18, 1918, Vernam, Parker, Lyman F. Morehouse, 
equipment engineer of the telephone company, and Edward Watson  
explained the Vernam system, together with some other possibilities, to a 
Lieutenant Griffiths. On March 27, the engineers conferred with 
colleagues of the Western Electric Company, A. T. & T.'s manufacturing 
subsidiary, and began constructing a couple of Vernam devices, using as 
many standard parts as 
I 
possible. They hooked them up to two teletypewriters and,-in the 
Western Electric laboratory, ran the first tests of what the engineers 
called "automatic cryptography." The devices worked like a charm. A. T. 
& T. reported this to the Army. Major Joseph O. Mauborgne, then head of 
the Signal Corp's research and engineering division, came, saw and was 
conquered. Except for the problem of the keys. 
In the first days of development, the Vernam keys took the form of 
loops of tape perforated with characters drawn from a hat, giving a 
random keytext. The engineers, who were rapidly learning about 
cryptology, probably from a 1916 manual, soon spotted the flaw in this. 
The Vernam system is a polyalphabetic. A 32 X 32 tableau may be set up 
with the 32 characters of the Baudot alphabet across the top as plaintext 
and down the side as keys. Because the Baudot alphabet is public 
information, the composition of the 32 cipher alphabets filling the body 
of the tableau would be known. Secrecy in the Vernam system thus 
resides entirely in its keys. Looped keytapes would pass through the 
Vernam mechanism at regular intervals, permitting a simple Kasiski 
solution, even though the key recovered would be incoherent. The 
engineers made the keytapes extremely long to increase the difficulty of 
such a solution. But then the keytapes became too hard to handle. 
Engineer Morehouse surmounted these difficulties by combining two 
short keytapes of different lengths in a Vernam device as if one were 
enciphering the other and using the extremely lengthy output—called the 
secondary key—as the key for plaintext. If one loop were 1,000 
characters long and the other 999, the one-character difference would 
produce 999,000 combinations before the sequence would repeat. Thus 
two tapes each about eight feet long would breed a key that would extend 
8,000 feet on a single tape. This was a major practical improvement. 
But Mauborgne recognized that even this system was not immune to 
cryptanalysis. The future Chief Signal Officer, then 36, was an 
extraordinary cryptanalyst. He had studied the subject at the Army 
Signal School with an expert, was thoroughly conversant with its 
techniques, had devised a solution for the hitherto unsolved Playfair, and 
almost certainly knew of Friedman's Riverbank Publications, including 
No. 17 on solving running-key cryptograms. He therefore saw that heavy 
traffic raised the possibility of a Kerckhoffs superimposition, even with 
the 
two-tape system. Moreover, probable words would enable the 
cryptanalyst to recover the secondary key. He could then test the various 
possibilities for the two primary keys at intervals of 999 and 1,000 
letters, and so gradually build them up. Mauborgne demonstrated this to 
the A. T. & T. engineers with the keywords RIFLE and THOMAS. 
Mauborgne had himself perhaps participated in work at the Army 
Signal School several years earlier that had concluded (before Friedman's 
solution) that the only safe running key was, in Parker Hitt 's words, one 
"comparable in length with the message itself." Mauborgne's study of the 
A. T. & T. system brought this home to him more forcefully. Any 
repetition of any kind in the keys of cryptograms under analysis imperils 
them and perhaps dooms them to solution. It does not matter whether 
the repetitions lie within a single message or among several, arise from 
the interaction of repeating primary keys or from the simple repeating of 
a single long key. Repetitions in the key could not be permitted. At the 
same time, Friedman's work had demonstrated that running keys could 
not be intelligible. To avoid the Scylla of repetition and the Charybdis of 
intelligibility, keys would have to be, Mauborgne realized, both endless  
and senseless. He therefore welded together the randomness of the key, 
created, perhaps almost accidentally, by Vernam, and the non-repetition 
of the key, discovered by the Army Signal School cryptologists, into what 
is now called the "one-time system." It consists of a random key used 
once, and only once. It provides a new and unpredictable key character 
for each plaintext character in the whole ensemble of messages ever to be 
sent by a group of correspondents. 
And it is an unbreakable system. Some systems are unbreakable in 
practice only, because the cryptanalyst can conceive of ways of solving 
them if he had enough text and enough time. The one-time system is 
unbreakable both in theory and in practice. No matter how much text a 
cryptanalyst had available in it, or how much time he had to work on it, 
he could never solve it. This is why: 
To solve a polyalphabetic cipher is essentially to gather all the letters 
that are enciphered in a single alphabet into a homogeneous group that 
may be studied for its linguistic traits. The techniques of this collection 
differ, as do the kinds of keys. Thus a Kasiski examination sifts out the 
identically keyed letters in a repeating key. A running key with a 
coherent text can be solved by reciprocally reconstructing the plaintext 
and the keytext. A running key with a random text used in two or more 
messages succumbs to a simultaneous reconstruction of the two 
plaintexts, one checking the other. Other polyalphabetics, such as the 
autokey and the two-tape system, engender specialized solutions that 
stem from their own peculiarities. The monoalphabetically enciphered 
letters that are the goal of these techniques also exist in a Vernam one-
time system cryptogram because the 32 available cipher alphabets are 
used over and over again. But the cryptanalyst has no way of sorting 
them out because the key in a one-time system neither repeats, nor 
recurs, nor makes sense, nor erects internal frameworks. Hence, his 
methods, all based in one way or another on these characteristics, all 
fail. The perfect randomness of the one-time system nullifies any 
horizontal, or lengthwise, cohesion, as in coherent running key or 
autokey, and its one-time nature bars any vertical assembly in Kasiski or 
Kerckhoffs columns, as in keys repeated in a single message or among 
several messages. The cryptanalyst is blocked . 
How about trial and error? It seems as if brute testing of all possible 
keys, one after another, would eventually yield the plaintext. Success 
this way is an illusion . For while exhaustive trials would indeed bring out 
the true plaintext, they would also bring out every other possible text of 
the same length, and there would be no way to tell which was the right 
one. Suppose that the cryptanalyst deciphers a four-letter military 
message with every key, beginning with AAAA. He strikes plaintext at key 
AABI : kiss. Unlikely in this context. He presses on. Key AAEL yields 
plaintext kill. Better—but he wants to make sure. He continues through 
key AAEM, giving  kilt , which might be an oblique reference to a Scottish 
maneuver, and AAER, kiln. Further down the line he reaches fast at 
GZBM and slow at KHIA, stop at HRIW and gogo at XSTT, hard at PZVQ 
and easy at RZBU. He finds when he ends at ZZZZ that he has merely 
compiled a list of every possible four-letter word—the hard way. He can 
no more pick the right solution from this list than he can from a 
dictionary of military terms. The key does not help in limiting the 
selection because, since it is random, any group of four letters is as 
acceptable a keytext as 
any other. The worst of it is that the possible solutions increase as the 
message lengthens. There are only three possible solutions for a one-
letter cryptogram, but dozens for those of two letters, and zillions for 
those of 100. 
A final hope flickers. Suppose that the cryptanalyst obtains the 
plaintext of a given cryptogram, perhaps through theft or the error of a 
radio operator. Can he use the key that he can recover to determine the 
system on which that key was built, and so predict future keys? No, 
because a random key has no underlying system—if it did, it would not 
be random. 
These are empiric proofs. It is possible, however, to demonstrate a 
priori that the one-time system is unbreakable. This constitutes the proof 
that it is theoretically unbreakable. 
In essence , the Vernam encipherment constitutes an addition—an 
addition based on the Baudot alphabet, but an addition nonetheless. 
Suppose then that the plaintext is 4 and the key is 5. The ciphertext will 
be 9. Now, given only this, the cryptanalyst has no way of knowing 
whether it results from the addition of 7+ 2, or 6+ 3, or — 2 + 11, or 4 + 
5, or any other of the 32 possible combinations. Generalized, the 
situation is x + y = 9. Mathematicians call this an equation in two 
unknowns, and a single such equation has no unique solution. Two 
equations with the same two unknowns are required. The one-time 
system prevents the cryptanalyst from ever bringing two or more such 
equations together. The utter absence of any pattern whatsoever within 
its key precludes him from finding two occurrences of a given key 
character by reconstructing a pattern. And the tape's exhaustless novelty 
makes it impossible for him to locate these occurrences in any key 
repetitions. The cryptanalyst is thus denied any chance of getting 
additional information to delimit one of the unknowns; he is left with all 
32 possibilities for the key character, and consequently all 32 for the 
plaintext. True it is that in the cryptanalytic case of an equation in two 
unknowns, some solutions are more probable than others. Thus, there is 
a 12 per cent chance that the plaintext unknown is e, an 8 per cent 
chance that it is t, and so on down the frequency table. But this does not 
answer the cryptanalyst's question, for it does not specify which of these 
probabilities is actually present in the individual case before him. 
So the answers again evade the cryptanalyst. Formless, endless, the 
random one-time tape vanquishes him by dissolving in chaos on the one 
hand and infinity on the other. Here indeed the cryptanalyst gropes 
through caverns measureless to man. His quest is Faustian; who would 
dare it would know more than can be known. 
Why, then, is this ultimate cipher not in universal use? Because of 
the stupendous quantities of keys required. The problems of producing, 
registering, distributing, and canceling the keys may seem slight to an 
individual who has not had experience with military communications, 
but in wartime the volumes of traffic stagger even the signal staffs. 
Hundreds of thousands of words may be enciphered in a day; simply to 
generate the millions of key characters required would be enormously 
expensive and time-consuming. Since each message must have its 
unique key, application of the ideal system would require shipping out 
on tape at the very least the equivalent of the total communications 
volume of a war. In fact, however, considerable extra key material would 
have to be supplied. A group of subordinate units may possess some tape 
in common for intercommunication, but once one unit uses a roll of 
keytape, the others must cancel their identical rolls. In practice, this step 
is the most difficult. It is virtually impossible in the hubbub of battle to 
monitor the messages of a dozen other units to determine what keytapes 
they have used. 
In general, the physical problems bar employing a onetime system in 
a fluid situation, such as military operations in the field. These 
difficulties do not hold for more stable situations, such as exist at high 
military headquarters, at diplomatic posts, or in a two-way spy 
correspondence— and in such situations one-time systems are 
practicable and are used. Even here, however, difficulties arise if traffic 
volume is heavy. 
But though the device was an engineering success, it proved a 
commercial failure. Cable companies and business firms, which A. T. & 
T. hoped would buy cipher attachments for its teletypewriters, passed it 
over in favor qf the old-fashioned commercial codes, which substantially 
shortened messages, thereby cutting cable tolls, and which gave a 
modicum of secrecy as well. The armed forces budgets had shrunk to 
their peacetime tightness; crypto-logically, the physical difficulties forced 
Army communi- 
cators back onto the two-tape system, and the demonstrated 
solvability of this threw the whole Vernam arrangement into temporary 
limbo. 
The Army revived it in a hurry as SIGTOT when World War II loomed, 
but by then Vernam was well out of it. He had continued developmental 
work at A. T. & T. for several years. He improved his own system,* 
invented a device for enciphering handwriting during telautograph 
transmission, and came up with one of the earliest forms of binary digital  
encipherment of pictures—another precocious development. He was so 
good that he was grabbed off at a substantial raise by International 
Telephone and Telegraph Corporation's research subsidiary, 
International Communication Laboratories, which was doing some 
cryptographic work. Four months later the stock market crashed. 
Vernam, with no seniority, was soon out. He went to Postal Telegraph 
Cable Company, which merged with Western Union. His inventive spark 
flared from time to time, and he was granted 65 patents in all, among 
them such important noncryptologic items as the semiautomatic torn-
tape relay system, the push-button switching systems, and finally the 
fully automatic telegraph switching system, all for the Air Force's 
200,000-mile domestic network . 
But the reversal in his personal fortunes seemed to depress him. Each 
night he sank deeper and deeper into the newspaper. Finally, on 
February 7, 1960, after a long bout with Parkinson 's disease, the man 
who had automated cryptography died in obscurity in his home in 
Hackensack, New Jersey. 
 
The history of science is replete with coincidence. Adams and 
Leverrier deduced the existence of Neptune almost simultaneously. While 
Darwin was elaborating his theory of evolution, Wallace sent -him a short 
paper that succinctly set it forth. Five years after Morse invented his 
telegraph, Wheatstone independently invented another. So it is not 
surprising that coincidence brushed cryptography 
*In its original form, the ciphertext included the stunt characters. 
This made it difficult to record the ciphertext on paper. The sudden 
appearance of a figure shift would abruptly convert a literal cryptogram 
into one of numbers and punctuation marks. A carriage return without a 
paper feed would result in an overline. To prevent this, Vernam added 
some circuits that would cause the stunts to print as two-letter groups. 
in the crucible years of the First World War and just after. Its fabled 
long arm reached out and tapped four men in four countries. Spurred by 
the vast wartime use of secret communications, and beckoned by the 
new age of mechanization, they independently created the machine 
whose principle is perhaps the most widely used in cryptography today. 
This principle is that of the wired code-wheel, the rotor. 
The body of a rotor consists of a thick disk of insulating material, 
such as Bakelite or hard rubber , commonly two to four inches in 
diameter and half an inch thick. Embedded around the circumference of 
each face are 26 evenly spaced electrical contacts, often of brass . Each 
contact is connected at random by a wire to a contact on the opposite 
face. Thus a path for an electric current is set up that starts at one point 
on the circumference of one side and ends at another point on the other. 
The contacts on the starting, or input, face represent plaintext letters 
and those on the output face ciphertext letters. The wire connections 
between the two then provide a way of converting plaintext letters to 
ciphertext. To encipher, one need only fire a burst of current into the 
rotor at the input contact of the desired plaintext letter, say, a; this 
current then courses along the wire to emerge at an output contact 
representing the ciphertext letter, say, R. If a list be drawn up of all the 
rotor's wire connections from the plaintext to the ciphertext face, it will 
constitute a monalphabetic substitution alphabet. The rotor thus 
embodies a cipher alphabet in a form suitable for electro-mechanical 
manipulation. 
When the rotor turns, however, the current entering at a specific point 
will no longer emerge at the same point as before. The plaintext letter 
that in the previous position was enciphered to x is now enciphered to 
something entirely different. The rotor thus will produce as many cipher 
alphabets as it has positions, usually 26. Now, several rotors may be 
placed side by side. The current that represents a letter will traverse their 
internal maze to encipher that letter. A turn of any rotor will alter that 
maze and so change the letter's encipherment. If each rotor turns a 
space only when the preceding rotor has completed a revolution, the 
number of alphabets that the array of rotors creates will equal the 
product of the number of positions that each rotor can take. Five rotors, 
each with 26 positions, will thus generate 11,881,376 cipher 
alphabets. This hemmorhaging profusion will provide a different alphabet 
for each letter in a plaintext longer by far than the complete works of 
Shakespeare, War and Peace, the Iliad, the  Odyssey , Don Quixote, the 
Canterbury Tales, and Paradise Lost all put together. 
A period of that length thwarts any practical possibility of a 
straightforward solution on the basis of letter frequency. This general 
solution would need about 50 letters per cipher alphabet, meaning that 
all five rotors would have to go through their combined cycle 50 times. 
The cryptogram would have to be as long as all the speeches made on the 
floor of the Senate and the House of Representatives in three successive 
sessions of Congress. No cryptanalyst is likely to bag that kind of trophy 
in his lifetime; even diplomats, who can be as verbose as politicians, 
rarely scale those heights of loquacity. 
Consequently the cryptanalyst must fall back on special cases. They 
furnish him with what he must have for a practicable rotor solution: the 
plaintext for a length of ciphertext. He can get this in several ways. A 
Kerckhoffs superimposition is possible when several messages begin at 
the same rotor setting, or with settings so close to one another that the 
cipher-alphabet sequence overlaps among messages. Statistical tests will 
reveal these. Sometimes two cryptograms have the same plaintext: one 
was sent in the wrong key, or identical orders are being sent to several 
units. Probable words or stereotyped beginnings will sometimes provide 
good clues. And sometimes the plaintext itself becomes available, 
through wireless queries, a cipher clerk's carelessness, published 
diplomatic notes, and the like. All of these situations have occurred often 
enough for the cryptanalyst to exploit them. 
That exploitation entails resolving the millions of secondary alphabets 
into the few primary ones. It calls upon the resources of higher 
mathematics, especially group theory, whose techniques are particularly 
suited to handle the many unknowns involved in a rotor solution. 
Basically these unknowns are the paths taken by the wires of each rotor 
from one face to the other. The cryptanalyst-mathe-matician quantifies 
them by measuring the distance, or displacement, between the input and 
the output contacts. For example, a wire from input contact 3 to output 
contact 10 marks a displacement of 7. Similarly, letters are given 
numerical values, usually a = 0, 6 = l,...z = 25. Using his known or 
assumed plaintext values, the cryptanalyst sets up equations in which 
the displacements of the several rotors constitute the unknowns, and 
then, using higher algebra, solves the equations for them. By repeating 
this process, the cryptanalyst can list the differences between many of 
the displacements on the rotor. He can then seek an arrangement of 
wires having these differences that will reproduce the known 
cryptographic effects. In similar fashion, he will reconstruct another 
rotor. Such are the basic principles of the rotor solution. But their 
practice wracks the cryptanalyst with some of the most excruciating 
mental torture known to man. And so the rotor system produces an 
extremely complex and secure cipher from simple elements in a simple 
construction. Who are the four contrivers of this miniature labyrinth, the 
four modern Daedaluses of cryptography? 
 
The inventor of the first machine to embody the rotor principle gave 
the best efforts of his life to it. Edward Hugh Hebern was born April 23, 
1869, in Streator, Illinois, and was raised in the Soldiers' Orphan Home 
in Bloomington. When he was 14 he began living and working on a farm 
near Odin, where he got a high school education. He headed West at 19, 
and, after selling a timber claim in California to a sawmill where he 
worked for a time, he turned to carpentry and built and sold houses in 
Fresno. Soon after he turned 40, he somehow became interested in 
cryptology. Hebern was at this time a blue-eyed, brown-haired man of 
medium height and build, mustachioed, quiet, a great reader, kind, and 
even-tempered. 
From 1912 to 1915, he filed for patents for cryptographic check-
writing devices, cipher keyboards for typewriters, movable letter blocks to 
form mixed reciprocal monoalphabets, and a ciphering typewriter. In 
1915, he devised an arrangement in which two electric typewriters were 
connected by 26 wires in random fashion; thus when a letter was struck 
on the plaintext keyboard, it would cause a ciphertext letter to print on 
the other machine. Since the wires remained plugged into the same jacks 
during an entire message, the cryptogram would be monoalphabetic—but 
it would have been electromechan-ically enciphered. 
The wire interconnections comprised the germ of the rotor—a means 
to vary the monoalphabetic encipherment. In 1917, Hebern reduced his 
ideas to the first drawings made of a rotor system, which, a year later, 
grew into actual apparatus. 
Early in 1921, he advertised an "unbreakable" cipher in a marine 
magazine, but Miss Agnes Meyer , a crypt-analyst in the Navy's Code and 
Signal Section, solved the sample message. When Commander Milo F. 
Draemel, the officer in charge, sent Hebern the solution, he came at once 
to Washington and showed the Navy his machine, filing his first rotor 
patent while he was there. The Navy had been looking, a director of naval 
communications later recalled, for "something radically better [in secret 
communications]. Something automatic came into our minds, and it had 
been in the back of our heads for some time. Along came Mr. Hebern 
from the West Coast with the Hebern machine. He made one, as I recall, 
and we were very thrilled when he showed us what it could do. ... I 
remember we wanted to get some right away for the whole Navy." 
Hebern had, in 1921, incorporated Hebern Electric Code, the first 
cipher machine company in the U.S., and with this kind of 
encouragement from the Navy, and believing—rightly—that his new rotor 
device was the cipher machine of the future, he began selling shares in 
his firm to raise capital. Since it controlled scores of patents in the 
United States and abroad, not only on the cipher machine but on such 
other pioneering devices as electric typewriters and directional indicators 
for cars, he had no trouble selling about $1,000,000 worth of stock to 
2,500 shareholders, mostly from Oakland, where he then lived. But he 
overexpanded, building a grandiose factory , and in 1926 Hebern Electric 
Code, Inc., went into bankruptcy. 
Hebern refused to give up. Pinning his hopes on the Navy, he 
incorporated the International Code Machine Company in Reno , Nevada. 
Things started to look up in 1928 when he sold four five-rotor machines 
to the Navy at $750 for each machine and $20 for each rotor. Hebern 
and a handful of employees had built them by hand, and he himself then 
drove them to the 12th Naval District Office in San Francisco.  
 
[Codebreakers 208.jpg]
Edward Hebern's "Electric Code Machine," U.S. Patent 1,683,072. Rotors are 75a-e; 
plates, IS, 20, 21; the output letters glow  behind the imprinted windows 37 
 
One machine stayed there; the others were sent to the Navy 
Department and to the commanders in chief of the United States Fleet 
and the Battle Fleet for field tests. The Navy wanted to determine their 
mechanical reliability rather than their cryptographic capabilities, which 
were regarded as satisfactory, even though Friedman had made a 
cryptanalytic breakthrough and solved the first rotor system. During 
1929 and 1930 these machines handled a considerable portion of the 
Navy's official high-command communications. Things looked even better 
for Hebern in 1931, when the Navy purchased 31 machines for $54,480. 
These were not experimental machines, but were issued to the more 
important flag officers as the top cryptographic system in the United 
States Navy. In 1934, Hebern, who was continually trying to improve his 
machines, submitted one that proved a complete failure. The officer who 
had dealt most with him, Safford, was on sea duty, and some Navy man 
who did not know Hebern sent him an abrupt and discourteous letter, 
discontinuing business with him. As Safford later put it, "They pulled the 
rug out from under Hebern and were not even polite about it." 
That virtually ended Hebern's chances, for although his machines 
were still in service, when they wore out in 1936 after carrying heavy 
loads of traffic they were replaced by another, non-Hebern cryptographic 
system. Interestingly, the Hebern machines themselves were renovated 
and sent to shore stations, where some remained in use until 1942. Two 
were, in fact, captured by the Japanese during World War II. 
During this time, Hebern was living on income from properties left by 
his wife's sister. He continued to improve his machines and to take out 
patents, despite the setback of losing a patent interference case against 
International Business Machines in 1941. In 1947, convinced that the 
armed forces had used his basic ideas throughout the war without 
compensating him for them, he filed a claim of $50,000,000 against the 
three services. In the six-year period that this remained entangled in 
bureaucratic red tape, Hebern died. He was 82, and had suffered a heart 
attack on February 10, 1952, while trying to lift a box that was too heavy 
for him. 
Early in 1953, the departments of the Army, Navy, and Air Force 
rejected his claims, and a few months later his estate sued the 
government for the $50,000,000. On the basis of legal technicalities, the 
United States Court of 
Claims limited the period of recovery to 1947-1953 and the 
infringement question to the exceedingly narrow one of a particular dog 
arrangement for turning the rotors. Ignored was the basic question of 
whether the armed forces had adopted the rotor principle from Hebern 
and used it without just compensation in hundreds of thousands of 
high-security machines in World War II and in the cold war—which they 
had unquestionably done. Ignored were the ethics of having obtained 
Hebern's best developmental efforts on the implied promise of large 
production contracts, which were awarded instead to the Teletype 
Corporation. 
The government, taking refuge from the spirit of justice in the letter of 
the law, fought to keep from giving him a penny. In 1958, it finally 
settled for the pittance of $30,000—and not out of a sense of fair play, 
but because it feared that the court's sense of right would compel it to 
bare some cryptographic secrets. The payment was disproportionate to 
Hebern's contribution, which was worth, not $50,000,000, to be sure, 
but $1,000,000 at the least. Hebern deserved better. His story, tragic, 
unjust, and pathetic, does his country no honor. 
 
Three others independently invented the rotor during the immediate 
post-World War I years. A Dutch engineer, Hugo Alexander Koch, 49, 
viewed the system most comprehensively, pointing out in his patent that 
steel wires on pulleys, levers, rays of light, or air, water, or oil flowing 
through tubes could transmit the enciphering impulse as well as 
electricity. A German, Arthur Scherbius, produced a machine called the 
Enigma. It failed commercially during the 1920s but became the 
standard cipher machine for all three armed forces when Hitler rearmed 
Germany in the 1930s. A Swedish inventor, Arvid Gerhard Damm, 
patented a cumbersome mechanism that seems never to have been built. 
The company that he founded likewise had at first no commercial 
success. But a young man, son of one of the investors in the firm, 
changed all that. 
Boris Caesar Wilhelm Hagelin, born on July 2, 1892, in the Caucasus, 
where his father was working, studied for three or four years in St. 
Petersburg, then returned to Sweden and was graduated from the Royal 
Institute of Technology in Stockholm in 1914 with a degree in 
mechanical engineering. He worked six years for ASEA, 
Sweden's General Electric, and one in the United States for the 
Standard Oil Company (New Jersey). In 1922, his father put him into the 
Damm firm to represent his investment. 
Three years later, while Damm was in Paris, young Hagelin learned 
that the Swedish military was considering buying the Enigma. He 
simplified one of the Damm mechanisms. The Swedish Army liked it, 
and, in 1926, placed a larger order. 
On the verge of success, Damm, early in 1927, died. Aktiebolaget 
Cryptograph, which was in poor financial shape but which had a big 
order in its pocket, was purchased at a good price by the Hagelin 
interests and reorganized as Aktiebolaget Cryptoteknik, 14 Luntmakare-
gatan, Stockholm. Boris Hagelin ran the firm. He saw that printing 
cipher machines were faster, more accurate, and more economical in 
terms of manpower than indicating mechanisms like the Enigma, which 
lit bulbs to indicate plain- or ciphertext letters. To the army machine he 
added a printing mechanism. The whole apparatus weighed 37 pounds, 
operated at 200 characters a minute, and could be carried inside a case 
about the size of an attaché case. 
This was the most compact printing cipher machine available in 1934, 
when the French general staff asked Hagelin for the impossible: a pocket-
sized cipher machine that would print the ciphertext and so permit one-
man operation. He first whittled a piece of wood that would fit into a 
pocket to mark the limits of his dimension. While trying to concoct a 
mechanism that would fit inside such space and also produce an 
effective cipher, he bethought himself one day of a construction that he 
had conceived three years before for the inventors of a vending machine. 
It was an adding device that would accept different amounts of money, 
and it consisted of bars arranged in a cylindrical cage with lugs 
projecting from them in rows. There were 10 lugs in one row, 8 in the 
second, 4 in the third, 2 in the next, and 1 in the last; by combining 
these rows in various ways any number from 1 to 25 could be produced. 
This was just what he needed. The inventors had given him the rights to 
it when they could not pay for the prototype that he fabricated. He now 
adapted it so that the rows would shift a cipher alphabet to any one of 25 
positions, thus giving a plaintext letter any one of 25 ciphertext 
equivalents. And to produce the combinations 
I 
of numbers for these shifts, he could employ the keywheels with the 
variable number of projecting pins that he had used in his Swedish army 
machine. 
Hagelin shrank the device to 6 X 4V& X 2 inches— smaller than the 
base of a standard telephone set—and to under three pounds, or about 
the weight of a dictionary-sized codebook. To operate it, the encipherer, 
after first setting the key elements, twirled a knob at the left to the 
plaintext letter, and revolved a handle at the right. The mechanism spun, 
and a little typewheel printed the output on a gummed tape. Hagelin 
even managed to have it print the ciphertext in five-letter groups and the 
plaintext in normal word-lengths (by using a rare letter as a word-
spacer). Its speed averaged 25 letters per minute. 
In essence, it is a gear with a variable number of teeth. These turn a 
cipher alphabet through as many positions as there are teeth for that 
particular encipherment. The various parts of the mechanism interact to 
produce an incoherent running key with a very long period. Moreover, it 
proved exceedingly rugged, and this plus other operational advantages 
and the ease of changing the key largely overcame its mediocre security, 
which resulted from its use of a normal instead of a mixed alphabet as 
the cipher alphabet. 
From a purely mechanical point of view the device is an absolute 
marvel . Hagelin has engineered a mechanism that spouts an extremely 
long key from relatively few elements in an astonishingly compact format, 
which also permits of practically unlimited key changes. It is the most 
ingenious mechanical creation in all cryptography. 
This was the Type c-36, and when the French saw it, they snapped it 
up. Their 1935 order for 5,000 machines proved the turning point in the 
firm's fortunes. 
That same year, Hagelin began corresponding with American 
cryptologic authorities about the c-36. He went over himself in 1937, and 
again in 1939 when war broke out in Europe. Now the United States was 
considerably more interested. Friedman suggested improvements, and 
Hagelin returned to Sweden to incorporate them and to streamline the 
machine for mass production. On April 9, 1940, he was in his cabin in 
Dalecarlia when he heard a radio announcement that the Germans had 
invaded Norway . His wife told him that if he wanted to do anything with 
his machine in the United States, he ought to go there at once. 
 
[Codebreakers 213.jpg]
Boris Hagelin's M-209. 1 Outer cover 2 Inner cover 3 A lug 4 Encipher-decipher knob, set 
at D for decipher 5 Paper tape 6 Letter counter 7 Indicating disk, on which input letters 
are set 8 Reproducing disk, on which output letters are shown 9 Typewheel, which prints  
output letters 10 Windows to display keyletters on keywheels 11 Power handle 12 Cage 
disk, numbered for each slide-bar 13 A slide-bar, which moves left to become a tooth of 
the variable gear 14 Keywheel advance gear 15 Upper part of angled face of  guide  arm of 
keywheel 4; lugs in column 4 will strike it as cage rotates forward, driving slide-bars to 
the left 16 Pin for S on keywheel 4, in ineffective position 17 Keywheel 5 
 
"A normal visa was unobtainable," he has recalled, "so I induced the 
Swedish foreign office to send me as a diplomatic courier. My wife and I 
sent our luggage off in advance and took the train up to Stockholm. 
There we learned that the travel bureau had cancelled all trips to the 
United States, as the Germans had by now invaded France, Holland, and 
Belgium . We decided to take a chance and try to sail from Italy. 
"With the blueprints in my briefcase and two dismantled ciphering 
machines in a bag, we boarded the Trelleborg-Sassnitz-Berlin express. 
Our luck held. We rattled right through the heart of Germany and 
arrived unmolested three days later in Genoa. That night the windows of 
our hotel were smashed—because we had innocently chosen to stay at 
the Hotel Londra and Italy was now at war with Britain. But we reached 
New York on the last outward-bound voyage of the Conte di Savoia." 
This breathless escape proved worth it. The U.S. Army liked the 
machine, though it insisted on further tests. Hage-lin got 50 machines 
flown out secretly from Stockholm to Washington for final exhaustive 
trials. They passed, and after long contract negotiations, the Army 
accepted the improved device as its medium-level cryptographic system. 
Under the U.S. military designation of Converter M-209, the Hagelin 
machine served in military units from divisions down to battalions. In 
1942, L. C. Smith & Corona Typewriters, Inc., began turning out about 
400 olive -drab Hagelin machines a day (compared to its output of about 
600 typewriters a day) in its 900-man factory at Groton, New York. More 
than 140,000 were produced. (Ironically, the Italian Navy also used it.) 
Hagelin's royalties ran into the millions of dollars. He became the first— 
and the only—man to become a millionaire from cryp-tology. 
12. Duel in the Ether:  I 
SHORTLY AFTER NOON on the tense 31st of August, 1939, the last day of 
peace that the world was to know for six years, Swedish businessman 
Birger Dahlerus met with 
Hermann Goring at the Nazi leader's large and richly furnished town 
house at 2 Leipzigerstrasse in Berlin. Dahlerus had been trying 
desperately to avert the onrushing cataclysm of war by flying between 
England and Germany as Goring's unofficial mediator. Britain had 
pledged to aid Poland if Hitler attacked her, and, in an effort to stave off 
actual warfare had proposed to both Germany and Poland that they 
negotiate their differences directly. At a few minutes past one, as 
Dahlerus and Goring were discussing the situation, an adjutant brought 
in a red envelope of the kind used for especially urgent affairs of state. 
Goring ripped it open. When he read its contents, he leaped from his 
chair and, striding angrily up and down, raged at Dahlerus that he had 
in his hands proof that the Poles were sabotaging every move toward 
negotiation. 
After a few minutes he calmed down enough to tell the Swede what 
had been in the envelope. It was a telegram from the Polish government 
in Warsaw to its ambassador in Berlin. It was in code, of course, but the 
cryptanalysts of Goring's Forschungsamt, who had long ago cracked the 
Polish diplomatic code, had reduced it to plaintext at once, translated it 
into German, and sent a copy to Goring via messenger. The entire 
process had taken the communications-intelligence agency less than an 
hour. 
At the" end of the telegram came a "special and secret message" to the 
ambassador: "Do not enter under any circumstances into any factual 
discussions...." To Goring this proved so conclusively that the Poles had 
no intention of negotiating in good faith that he copied the translation in 
his own hand for Dahlerus to show the British ambassador. The German 
Air Minister told Dahlerus that he was taking a great risk in doing this—
he undoubtedly meant jeopardizing Germany's possession of the Polish 
code—but felt that Britain should know how faithless the Poles were. 
In fact this was not a reason for going to war, but just another excuse 
to do so. The Germans were using Dahlerus as a cat's-paw, for at the 
very moment that Dahlerus entered Goring's home, Adolf Hitler was 
signing his "Directive No. 1 for the Conduct of the War." At daybreak the 
next morning German troops invaded Poland. And although the 
Forschungsamt solution of the Polish message had no role in that attack 
except to confirm the Nazis in their perfidy, it did demonstrate the 
keenness and efficiency of one of Germany's major intelligence weapons 
as she 
I 
embarked upon what she fondly thought would be her blitzkrieg of 
conquest. 
 
The cryptanalytic service of the German Foreign Office was created 
early in 1919, apparently at the suggestion of Kurt Selchow, a 32-year-
old former captain in the Army intercept service. Selchow became its 
administrative chief and staffed it with cryptologic acquaintances from 
the war. His organization was at first known as Referat I Z, the z section 
of Division I, Personnel and Budget, of the Foreign Office. It included 
both the cryptanalytic service (the Chifinerwesen) and the cryptographic 
(the Chiffrierburo), the latter twice as large as the former. Around 1936 a 
reorganization of the Foreign Office renamed I Z as  Pers z (pronounced 
"pers-zed"), the z section of the Personnel and Administrative Division. 
The z meant nothing—the division did not have 26 sections—and it may 
have been chosen because it seemed appropriate to cryptology. Much 
later, Foreign Minister Joachim von Ribbentrop took the Chiffrierburo 
under his own office. 
By 1939, Pers z had divided the Chiffrierwesen into two groups—one 
that dealt with ciphers, either as primary systems or as 
superencipherments, and that was heavily mathematical in personnel 
and approach ; and one that dealt with codes and emphasized the 
linguistic.* Three senior cryptanalysts headed them— Rudolf Schauffler 
and Adolf Paschke as joint chiefs of the linguistic section, Dr. Werner  
Kunze as chief of the mathematicians. All were veterans of the military 
cryptanalytic bureaus that Germany had belatedly started in World War 
I; all joined the Foreign Office in 1919 when they were close to 30. 
Schauffler and Kunze participated in developing the one-time pad, the 
unbreakable cipher in pencil-and-paper form. 
These three were chiefly assisted by three other old-timers, Erich  
Langlotz, the third inventor of the one-time pad; Ernst Hoffmann , who 
held the title of Counsel for the High Cipher Service; and Hermann 
Scherschmidt, a specialist in Polish and other Slavonic codes. All usually 
held the same rank of Regierungsrat that Kunze, Schauffler, and 
Paschke did. In 1933, when Hitler came to power, Pers z employed about 
30 civil servants. As Germany re- 
*This division carries into the practical sphere the distinction that 
codes operate upon texts linguistically whereas ciphers operate 
nonlinguistically. 
armed, Pers z expanded, though slowly at first. Recruiting was subtle: 
prospective recruits did not know that they were being considered for the 
highly secret work of cryptanalysis. One woman, Asta Friedrichs, who 
had taught school in Bulgaria and knew that language, which Pers z 
needed, was simply asked if she would like to learn Serbo - Croatian and 
do some work involving it; she accepted, and not until after a 
probationary period was she told about the code-breaking. She began 
solving Serbo-Croatian codes, then some Bulgarian, then helped with 
others. 
With the outbreak of war, Pers z's growth became explosive. Among 
the brightest of its new members was Dr. Hans Rohrbach, a 37-year-old 
mathematician who later became editor of the oldest mathematical 
journal in the world, the Journal of Pure and Applied Mathematics. 
For several years, Pers z had been situated on the top floor of the 
library building just behind the Foreign Office main building in Berlin's 
Wilhelmstrasse. But by early 1940, it had burst out of these quarters. 
The mathematicians moved out first, into several flats in an apartment 
house at w-8 Jaegerstrasse that had been entirely taken over by the 
Foreign Office. Their departure relieved the crowding in the original office 
only temporarily, and soon the linguistic codesolvers found new offices, 
first in an anthropological museum, where they were surrounded by 
artifacts from Siam, and then in Dahlem, a suburb of Berlin. Here some 
worked in a garden apartment on a street called ImDol, some in a nearby 
girls ' boarding school, where they were joined in 1943 by the 
mathematicians. The combined group, the Chiffrierwesen arm of Pers z, 
called itself the Sonderdienst Dahlem ("Dahlem Special Service"). While 
there, during the middle period of the war, it consisted of about 200 staff 
members—20 to 25 mathematical crypt-analysts, probably the same 
number of linguistic crypt-analysts, the rest clerks and support staffers. 
Later it grew to 300. 
Heavy bombings—the workers had to spend nearly every night in air-
raid shelters—forced still another move in the summer of 1944. The 
linguistic branch moved 150 miles southeast to Hirschberg in Silesia, 
where they installed themselves in another school; the mathematicians 
moved to the nearby town of Hermsdorf. The odyssey of Pers z did not 
end even there, however. In February, 1945, the advance of the Russians 
compelled each group to move 
about 150 miles west. The mathematicians evacuated to Zschepplin 
Castle , near Eilenburg, about 80 miles south of Berlin. The linguists, 
joined by a few mathematicians to strip current superencipherments, 
moved into a wing of Burgscheidungen Castle near Naumburg , northwest 
of Wiemar. Here, as wartime guests of the Count von der Schulenburg 
and his five daughters, the 90 cryptanalysts, some with their wives, lived 
and worked amid art treasures and ancient furniture, handicapped by 
the almost total lack of liaison with the mathematicians, about 50 miles 
away. 
The ever-present problems of security added to the difficulties of Pers 
z. Ink was not permitted because it required blotting paper. Each night 
all papers had to be locked away. Waste paper had to be burned, and the 
ashes broken up to make sure that no cinder would float away. Later 
Pers z got a machine to shred the paper before it was incinerated. None 
of the codesolving groups was allowed to know what the others were 
doing—but these artificial barriers dissolved in the camaraderie of the 
Dahlem bomb-shelter. 
Security also meant political security, and even before the war the 
Nazis planted a spy in Pers z to watch for any signs of anti-Hitler activity. 
In 1942 Selchow became a Nazi. He took the honorary rank of 
Sturmfiihrer, which gave him access to three of four cars. The next year 
he became an Obersturmfiihrer because this gave him "a certain 
authority with the drivers ." However, he insisted, he never wore the 
uniform. Among the cryptanalysts, Paschke, Schauffler, and Kunze, at 
least, also joined the Nazi party. 
The cryptanalysts' raw material was intercepted by either military 
radio stations or the post office telegraph bureau. In Silesia, it came in by 
courier about noon. Most of the diplomatic messages bore address and 
signature, so few traffic-analysis problems of discovering language, 
cryptographic family, and the like, arose. The cryptanalyses required 
enormous volumes of text and corresponding quantities of statistics. The 
army of clerks, mostly women, compiled these, but it usually paid the 
cryptanalysts to work up a few statistics themselves. The solutions took 
a heavy toll of nervous energy. "You must concentrate almost in a 
nervous trance when working on a code," Miss Friedrichs recalled. "It is 
not often done by conscious effort." The solution often seems to crop up 
from the subconscious. 
The subconscious got considerable help, however, from an 
information group headed by Pastor Joachim Ziegen- 
riicker. The group collated information from radio broadcasts, Foreign 
Office memoranda, Allied newspapers (it read The Times throughout the 
war), and the Pers z output so that, as Miss Friedrichs said, they could 
give the answer when the cryptanalysts asked them "Who beginning with 
w spoke with somebody ending with n in a place with a kind of po on 
Thursday?" 
More help came from the financial bonuses that kept up the 
codebreakers' knowledge of foreign languages. The amount depended 
upon the difficulty of the tongue; nothing was paid for English and 
French, which they were expected to know anyway. The codebreakers 
had to take an examination in the language every four years to prove 
their continued competence, and many of them learned four languages, 
taking an examination each year and brushing up at the local Berlitz 
school for a month before the test. Pers z had experts in the language of 
almost every country large enough to maintain a diplomatic corps. One 
Olbricht attacked the difficult problems of breaking Chinese codes. A 
man named Benzing took such delight in the Turkish language and 
Turkish cryptanalysis that his confreres regarded him as a veritable 
Turcomaniac. 
The cryptanalysts received some of their greatest help from robots—
mechanisms that speedily performed some of the highly repetitious tasks 
required, or that simplified the handling of many items. Many were 
tabulating machines that used punched cards in ordinary ways. But 
many others were assembled out of standard parts for special purposes 
by Hans-Georg Krug , a former high school mathematics teacher who 
possessed a positive genius for this sort of thing. 
These Pers z robots helped solve codes of France and Italy, both of 
which used at times four-digit codes with additive superencipherments. 
One English code, however, remained invulnerable, because the 40,000-
group length of her additive key prevented enough material from 
accumulating. At the start of World War II, most countries probably 
employed the additive system of enciphered code in a hierarchy of codes 
for their foreign services. Germany herself did, using sometimes a four-
digit, sometimes a five-digit code, only her additive was the one-time pad. 
Despite all the mechanical help, however, solution of most codes came 
right down to pencil-and-paper work by individual cryptanalysts. 
Such was the solution of the superencipherment of the Japanese TSU 
diplomatic code—the columnar transposition with blank spaces in the 
transposition blocks that American cryptanalysts called the K9 
transposition to the j!9 code. The Japanese embassy in the Soviet Union 
began relying heavily on this code in October of 1941, when the Soviet 
government moved its capital eastward from threatened Moscow to 
Kuibyshev. The diplomats had to stay close to the seat of government, 
and the Japanese may have junked their heavy cipher machine instead 
of moving it, using their paper codes instead. Pers z made its first break 
by spotting two messages which had patches of identical letters 
separated by nonidentical sections. Deducing that these differing 
portions represented the same placode text, the cryptanalysts compared 
the two messages until, in a single afternoon, they found a transposition 
and blank arrangement that yielded the same texts in a form that 
resembled legitimate codewords. In one of their greatest technical 
successes, the mathematical cryptanalysts cracked the approximately 30 
transposition and blank patterns; the linguists read the code, and the 
subsequent solutions pro vided the Germans with information about 
Russian war production and army activities. 
 
[Codebreakers 220.jpg]
Pers z solution of an encoded message of Robert  Murphy  to the State Department dealing 
with highly secret negotiations with General Weygand in North Africa in 1941 
Pers z was an old hand at reading American codes. It had long studied 
the American superencipherment. The codewords were only of the cucuc 
and cuccu types (c = consonant, v = vowel); to encipher, the code clerk 
split them into a single consonant and two cu or uc groups, then 
replaced these segments with substitutes from the appropriate tables. 
This superencipherment left the cucuc and cuccu configuration of the 
codegroup unchanged, and this regularity enabled the Pers z 
mathematicians to break first into this original system and, in 1940, into 
a modification of it._ Ironically, changes of superencipherment within a 
message, intended to provide greater security, furnished the German 
cryptanalysts with isomorphic repetitions that helped them reconstitute 
the superencipherment substitution. With the superencipherment 
stripped off, the linguistic group solved a big 72,000-group code with not 
too much trouble. Dr. Hans-Kurt Miiller was instrumental in this; he had 
an uncanny gift for seeing the outlines of the whole plaintext in the murk 
of the partial solutions. Miss Friedrichs assisted. 
They were greatly helped in their work by their knowledge of the 
activities of diplomat Robert Murphy, who in 1941 and 1942 was in 
North Africa, handling delicate negotiations with the Vichy French and 
paving the way for the Allied invasion of North Africa. Murphy insisted 
upon using the State Department codes to preserve his autonomy, even 
though American officers in Eisenhower 's command pointed out their 
insecurity. He was certain that the Germans had not broken his codes. 
In fact, however, the Pers z cryptanalysts had broken them enough to 
recognize the groups meaning For Murphy or From Murphy that recurred 
at the head of so many telegrams. "We knew what he was interested in, 
and this gave us clues," Miss Friedrichs said. These rapidly helped 
complete the solution of the big code. Murphy's communications so 
facilitated her work, she said, that when she saw him drive by one day 
after the war while she was interned in Marburg, "I wanted to stop him 
and shake his hand." 
Thus, as early as August 12, 1941, the state secretary of the Foreign 
Office could hand to von Ribbentrop fully solved copies of Murphy's 
telegrams of July 21 and August 2. The first reported that Murphy had 
transmitted Roose- 
velt's views on French North Africa to General Maxime Weygand, 
commanding there. The second transmitted a Weygand aide's request for 
an American promise of military assistance. The Nazis knew Weygand 
was no friend of theirs, but it was not until they had what a Vichy source 
called "documentary proof" of his dealings with the United States that 
they forced Vichy to dismiss him. Thus the solution of an American 
diplomatic code cost the United States much valuable time and work that 
it was forced to recommence with the new leaders of French North Africa, 
and it may ultimately have prolonged the war and cost the lives of 
American soldiers who fought in that theater. 
As the war progressed, the State Department gradually took the old 
solved codes out of service and replaced them with new cryptosystems. It 
thus choked off the German sources of information. To get them flowing 
again, Pers z launched, in 1944, a major effort to break the M-138. This 
top State Department system was a Jefferson cylinder in strip form—the 
alphabets are "peeled" off the disks and stretched onto paper strips. The 
work was primarily mathematical, with Hans Rohrbach, a 37-year-old 
doctor of mathematics, playing a leading role. Rohrbach and Miiller first 
divided the messages into " families " enciphered with the same strip 
arrangement, using repetitions as family resemblances. This meant that, 
in a given family, the first strip was always the same, the second was 
always the same, and so on. Stereotyped beginnings gave the crypt-
analysts many plaintext assumptions—Miiller was as adept at spotting 
words here as with the code. On each strip, the plaintext stood an 
unknown distance from the ciphertext. By comparing many such 
equivalents, both within a single strip and with the help of information 
from neighboring strips, the cryptanalysts mapped the letters on the 
strips to reproduce the original alphabet. Collaboration among the half-
dozen cryptanalysts was extremely close. Each man looked after his own 
families, but they conferred frequently so that each could try on his own 
sequence of strips the possibilities found by others. Helping them in their 
work was a mechanism that moved the strips up and down to align them 
quickly. Eventually Pers z recovered all the M-138 strips and read nearly 
all the messages. But by then they had lost much of their intelligence 
value, and any hopes that the solution would help in the future vanished 
when the strips were changed. 
 
The codes of small countries are usually simpler to solve than those of 
large, and not only because of intrinsic qualities as smaller code size and 
fewer codes and additive tables. Their personnel is less well trained, and 
so they often ask for repeats if, as happens more often than with major 
powers, they cannot decode a message. Moreover, not having the courier 
services or communications of larger and richer countries, they cannot 
get new codes to distant outposts as often as the large countries and so 
continue using the older codes too long. While their messages usually do 
not contain the crucial portents of those of great powers, their diplomats 
are sometimes well situated and can provide information of value. Yet 
even these small nations sometimes seem to have a feel for knowing 
when their codes are broken. "You just get to a point where you are 
reading a good part of the traffic when one morning you come in and it's 
all changed," said Miss Friedrichs. 
The Pers z solutions, typed up, went to Selchow. He submitted them 
to the state secretary of the Foreign Office before Ribbentrop became 
Foreign Minister, and afterwards to both the state secretary and the 
Foreign Minister's office, at Ribbentrop's order. Those for the Fiihrer were 
marked with a green "F." He did not always see them, since Ribbentrop 
did not dare give him bad news. Those that he did see, he did not always 
appreciate. Across the face of one long dispatch that gave considerable 
information on agricultural conditions in Russia, which bore importantly 
upon military possibilities, Hitler scrawled "Kann nicht bir stimme" ("This 
cannot be"). Nazidom preferred its own lies and. propaganda to 
unpalatable truths, and so, as Miss Friedrichs said, "Even if we had a 
plum, it was not considered as one." 
In April of 1945, the American front engulfed the crypt-analysts at 
Burgscheidungen Castle and swept past. A few days later, Haskell  
Cleaves, a Signal Corps officer from Maine, discovered what they were 
doing. Headquarters sent out a mixed commission of American, British, 
and French experts to interrogate them. On May 8, while the world was 
celebrating V-E Day, 35 of them were flown to London for interrogation. 
For the cryptanalysts of the German Foreign Office, the war had ended. 
What had they accomplished? They had achieved some remarkable 
technical successes, and for some that was enough. Kunze and the other 
mathematicians usually lost 
interest in a problem after its cryptanalytic difficulties had been 
surmounted. Even the codebreakers who were interested in their 
influence on their country's policy could rarely learn anything about it: 
the diplomats seldom told them, and Selchow stood between them and 
the users . Moreover, the effects were diffused over many messages, 
commingled with other sources of information, distorted by Nazi 
preconceptions, so that it was virtually impossible to single out 
cryptanalyzed information as critical in a specific event. Finally, and 
most important, Germany lost the war, reducing all the Pers z efforts in 
the final analysis to nullity. "As I am accustomed to say," said Schauffler, 
"a bridge builder can see what he has done for his countrymen, but we 
cannot tell whether our life was worth anything." 
Yet they read the secret communications of the British Empire, 
Ireland, France, Belgium, Spain, Portugal, Italy, the Vatican, 
Switzerland, Yugoslavia, Greece, Bulgaria, Rumania, Poland; Egypt, 
Ethiopia; Turkey, Iran , China, Japan, Manchukuo, Thailand; the United 
States, Brazil, Argentina, Chile, Mexico, Bolivia, Colombia, Ecuador , 
Peru, the Dominican Republic, Uruguay , Venezuela . Not every code of 
every country was always read, but the solution of the codes of 34 
nations of the earth suggests that, whether or not the Pers z 
cryptanalysts' life was "worth anything," the reckoning cannot involve  
whether they had done their duty. That they had. 
 
In the nightmare totalitarian jungle that was Nazi Germany, the 
bigwigs of National Socialism consolidated their positions by building up 
personal power structures. Extra power could come from the knowledge 
obtainable through intercepting communications. Thus it was that a few 
weeks after Hitler appointed Hermann Goring as Air Minister in his new 
government in 1933, the fat ex-air ace established an eight-man unit in 
his Air Ministry to do as much intercepting as possible. He called it the 
Forschungsamt ("Research Office"), but its research was highly 
specialized. Apparently attached to the minister's office, it bore no 
relation either to the research division of the Luftwaffe 's technical office 
or to the Luftwaffe's own military intercept and cryptologic unit. 
Goring installed the Forschungsamt in a requisitioned building on the 
Behrendstrasse, Berlin, but moved it at the end of 1933 to the Hotel am 
Knie in the suburb of Chariot- 
tenberg . He named as its first chief an old friend and loyal party 
member named Hans Schimpf, a former naval lieutenant who had once 
served as liaison between the Army and the Navy cryptologic 
organizations . In 1934 the unit did exactly what Goring expected it to do 
when it supplied him with information that helped him win Hitler to his 
side in the first great power struggle of the Third Reich — that between 
Hitler's oldest friend and closest associate in the Nazi movement, the 
homosexual Ernst Roehm, on the one hand, and Goring, Heinrich 
Himmler , head of the S.S. and the Gestapo , and the Junkers on the 
other. Roehm was shot, and soon thereafter Schimpf suffered the same 
fate, presumably because he had done his job so well that he knew too 
much. Goring replaced him with Prince Christoph of Hesse , younger 
brother of Prince Philip of Hesse, one of Goring's friends since the late 
1920s. Christoph, then in his mid-thirties, was the fourth and youngest 
son of the Landgrave of Hesse, former ruler of that principality and a 
member of one of the oldest traceable families in Christendom (to 
Charlemagne). Christoph became a ministerial director in the Air 
Ministry and also had the title of Oberfuhrer of the S.S. He died in Italy 
in 1941 and was replaced by one of the original members, Gottfried  
Schapper. 
The Forschungsamt tapped telephones, opened letters, solved 
encoded telegrams. Its reports were called Braune Blatter ("Brown 
Sheets"). A typical one, of March 19, 1945, which was passed to the 
economic division of the armed forces, reported that on March 14 the 
Swiss political department informed the Swiss embassy in Lisbon about 
an agreement reached with the Allies concerning railroad operations from 
southern France. The Forschungsamt also recorded the conversations of 
Goring and Hitler. These were passed to the appropriate government 
department for action or reference, if necessary. In its most famous case, 
it transcribed 27 conversations from Goring's office with various officials 
in Rome and Vienna that settled Austria's fate in the hours before the 
Anschluss . Ironically, one of those whose subservient words to an 
overjoyed Hitler were recorded for posterity was Prince Philip, emissary of 
the Fiihrer and brother of the chief eavesdropper. 
Christoph's membership in the S.S., or Schutzstaffel ("Protection 
Staff"), the notorious blackshirted strong arm of the Nazi party, pointed 
to a close relationship between the Forschungsamt and the S.D., or 
Sicherheitsdienst 
("Security Service"), the branch of the S.S. that served as the 
ideological watchdog for the Nazis. The S.D., for example, determined 
who voted the wrong way in German plebiscites by numbering the back 
of the ballots with milk , a simple effective secret ink. Its efforts were 
primarily internal, and since private citizens, even conspirators, seldom 
use complicated code or cipher systems, its crypt-analytic organization—
if it even had one—was small and nameless. This is not to say that the 
S.D. was not interested in other people's conversations: it probably did 
its share of telephone tapping and mail opening. 
After 1936, the S.D. extended its watchdog duties from just the party 
to the government as well, with a domestic branch and a foreign branch 
that would nullify dangers before they could be launched against the 
sacred soil of the German Reich. Probably the S.D. also broadened its 
communications activities somewhat. It filched a diplomatic telegram 
here and there, and listened in to diplomatic telephone conversations, 
even one, on May 7, 1940, between Prime Minister Neville Chamberlain  
of Britain and Premier Paul Reynaud of France—Chamberlain and Rey-
naud could certainly be considered enemies of Germany and the Nazi 
party. But the S.D. probably got most of the external communications 
intelligence that it needed from the Forschungsamt, which was quite as 
interested as the S.D. in preserving the Nazi regime. 
Himmler headed the S.S. as a party official; as a government official 
he headed the two Reich police organizations: the Gestapo, which 
handled political crimes, and the Kripo, or Kriminalpolizei, which dealt 
with ordinary crimes. Both had communication intelligence sections, but, 
as with the S.D., these probably concentrated primarily on telephones 
and mail and had but little cryptanalysis to do. 
In 1939, the party and government police organizations were merged 
as the R.S.H.A., the Reichssicherheitshaupt-amt ("Reich Central Security 
Office"). The Gestapo became Amt IV of the R.S.H.A., the Kripo Amt V. 
The government domestic watchdog branch of the S.D. evolved into the 
R.S.H.A. Amt III, Domestic Intelligence, and the foreign branch into Amt 
VI, Foreign Intelligence. Amt VI was charged with the production of 
secret information about enemy countries. 
It apparently directed its thoughts mainly to the more traditional 
methods of gathering such intelligence. But 
shortly after the Anschluss, Walter Schellenberg, a young S.D. official, 
seized the files of the Austrian secret service and found that among the 
most interesting documents were those on cryptanalysis. This find may 
have soon thereafter recalled to the mind of Wilhelm Hottl, a youthful 
Austrian staff member of the new R.S.H.A., the World War I deeds of the 
Austro- Hungarian cryptanalysts, which General Max Ronge had detailed 
in an exciting book. Hottl discovered that General Andreas Figl, former 
head of the Austrian Dechiffrierdienst, had been arrested by the Gestapo 
in 1938. Hottl got Heinz lost, then head of Amt VI, to free Figl and to 
install him as an instructor in cryptology in a villa in the Wannsee  
section of Berlin. Here he passed on his experience to a new generation. 
But such training takes time, and any intelligence that the R.S.H.A. 
obtained from communications continued to come to it from other 
sources. It seized an occasional plaintext telegram and somehow 
acquired a one-part Spanish code and used it to read intercepts. It also 
was granted what must have been the first opportunity in history to get 
codes wholesale. Yamato Ominata, Japan's intelligence chief in Europe, 
offered to deliver the Yugoslav general staff and Turkish, Vatican, 
Portuguese, and Brazilian codes for 28,000 Swiss francs, or about 
$20,000. The offer may well have been accepted, for all those codes were 
read at one time or another by various German agencies. 
In addition, the R.S.H.A. depended upon the military and the 
Forschungsamt for communications intelligence. Thus, in the autumn of 
1941, Schellenberg, who had become deputy chief of Amt VI, asked 
Reinhard Heydrich, head of the whole R.S.H.A., to contact both the 
Forschungsamt and the military. Schellenberg wanted them to 
concentrate their intercept posts and cryptanalysts on Vichy and 
Belgrade traffic for some information he needed. At about the same time, 
Heydrich called the chief of the Wehrmacht signal organization and 
asked him to send Schellenberg any information about American-
Japanese negotiations that he might obtain. 
Himmler disliked such dependency and in March of 1942 he sent 
Schellenberg to Goring's beautiful country house, Karinhalle, to urge 
that the Forschungsamt be incorporated into Amt VI. Goring greeted him 
in a Roman outfit, toga, sandals, and all, carrying his Reichmarschal's 
baton, and, after hearing Schellenberg, said vaguely, "Well, I will have 
a word about it with Himmler." Nothing happened, of course, and 
Schellenberg, who at this time became head of Amt VI, set up a well-
funded department, to carry out research in secret communications 
including invisible inks and microfilms as well as cryptography and 
cryptanalysis. Figl may well have been the nucleus of this group. It may 
have provided the digraphic cipher—ten tables 26 X 26, one of which was 
selected to encipher each message— that one R.S.H.A. radio net was 
using much later in the war. This system may have been adapted from 
the Army, which at one time used digraphic substitution as a field 
cipher. For internal communications, the R.S.H.A. used cipher machines 
supplied by the military. 
The new department did not, in any event, produce a great deal of 
communications intelligence, for Schellenberg continued to get most of 
his from the outside. Starting in 1942, he said, "Every three weeks or so I 
gave a dinner party at my home where the technical heads of the three 
services, Defense Ministry, Post Office [which unscrambled transatlantic 
telephone conversations], and Research Stations [Forschungsamt] 
discussed new developments and helped each other with their problems.* 
These meetings were perhaps more than any other single factor 
responsible for the high standard of the scientific and technical side of 
my service. It was the cooperation and interest which these people 
showed to me personally which made most of my success in Secret 
Service operations possible"—an unexampled acknowledgment of 
indebtedness to communications intelligence by a cloak-and-dagger man. 
The R.S.H.A. repaid some of this generous help with the products of 
the greatest spy coup of World War II— Operation Cicero. "Cicero" was 
Elyesa Bazna, an Albanian working in Ankara as the valet to Sir Hughe 
Knatchbull-Hugessen, British ambassador to neutral Turkey. Bazna had 
taken wax impressions of the keys to the black dispatch box which Sir 
Hughe kept beside his bed for the secret papers that he liked to pore over 
late at night. The valet would open the box, photograph the documents, 
and sell the rolls of film to the R.H.S.A. agent in Turkey, L. C. Moyzisch 
provided the Germans with information about Russian war production 
and army activities. 
  
*No Pers z representative appears to have attended—probably a 
reflection of the high-level personal dislikes and power struggles between 
Goring and Himmler on the one hand and Ribbentrop and the military on 
the other. At one point Goring tried to bring Pers Z within the ambit of 
the Forschungsamt. 
 
[Codebreakers229.jpg]
Encipherment table H-1 for a diagraphic cipher of an R.S.H.A. radio net in Norway 
 
The documents consisted largely of cables to Sir Hughe. They were of 
the highest importance—reports of Stalin -Roosevelt-Churchill 
conversations, for example. But when this information began streaming 
into Berlin in November and December, 1943, Hitler and other top 
officials refused to believe that it was genuine. "Too good to be true," Rib-
benthrop told Moyzisch. The fact is that he did not want to read therein 
the impending doom of the German Reich. 
The messages, which bore date-time notations, could help in breaking 
the British diplomatic codes, and though Pers Z would seem to have been 
the logical recipient, Schellen-berg gave the photographs to his 
communications-intelligence friends in the military. They cooperated 
fairly closely with Pers Z, however, and they probably passed the material 
to it. Pers z may also have gotten copies from Ribbentrop. Kunze and 
Paschke both saw Cicero documents and were unimpressed. For the 
British were by then superenciphering their most secret messages in a 
one-time pad. Though the Cicero messages may have contributed to the 
solution of some lesser British systems and so helped produce some 
minor information, they could not make possible the recovery of the one-
time keys of any other messages. Operation Cicero, so complete a 
success in one sense, was thus an almost total failure in another. 
At about this time, Hottl, the young man who had discovered Figl, 
became, at age 28, the head of Amt VI E— the Amt VI section for 
southeast Europe. He soon grew friendly with Hungarian Army 
intelligence, whose chief one day showed off his communications-
intelligence unit. The Hungarians did indeed have a fine organization, 
and it very much impressed Hottl. He thought that it did relatively more 
with its poor resources than did Pers z, the Forschungsamt, the German 
military cryptanalysts, and the police eavesdroppers all put together. In 
the middle of 1944, he convinced the pro-Nazi Hungarian Premier, Andor 
Sztojay, to have the unit furnish him with its results. The unit's 
commander, Major Bibo, who lived only for his work, agreed to 
concentrate on the traffic that Hottl wanted when Hottl promised him 
more men, better equipment, and extra money. 
Hottl went from room to room in Bibo's offices and picked out the 
choicest of the copious solutions. A few days later, he laid the sheaf 
before Schellenberg and said: "Please read this, and if you would like to 
have it regularly, give me a credit for the first 100,000 Swiss francs." But 
Schellenberg feared that Hitler, who distrusted the Hungarians because 
of their marked lack of enthusiasm for being an Axis partner , would not 
like the idea if he heard of it. He gave Hottl only a nominal sum. But 
Hottl wangled the francs out of the R.S.H.A. financial wizard, Friedrich 
Schwend—not too difficult a task, since the money was bogus. 
Within six months, the unit exceeded even Hottl's sanguine hopes by 
reading a goodly portion of the secret radiograms of embassies in 
Moscow. Figl seems to have joined it and become one of its star 
cryptanalysts, performing some minor miracles in his room with pots of 
black coffee and packs of cigarettes whenever the unit was stumped. 
Bibo's interceptors and cryptanalysts had become the R.S.H.A.'s first 
major source of its own of foreign communications intelligence. It could 
read some American and British messages, especially in 1945, when it 
acquired a cryptanalyst "who could sift the unimportant from the 
important with the sureness of a sleep- walker ." It read almost all the 
radio traffic of the Turkish embassy, learning that Stalin deeply 
suspected his Anglo-American allies and feared that they might conclude 
a separate peace with Germany. The reports of the Turkish military 
attache1, Hb'ttl was told by General Alfred Jodl, chief of the Wehrmacht 
operations staff, contained the most valuable information about Russia 
that the high command then had. By this time, about the end of 1944, 
the advancing Russians forced the unit to retreat from Budapest to the 
Odenburg hills and, three months later, to an Alpine redoubt. These 
disruptions did not choke off the flow of intelligence, which ended only 
when the war did. 
"I do not want to exaggerate the importance of what we achieved, 
although in this one year of my collaboration with the Hungarians there 
were at least a hundred successes such as seldom fall to the lot of a 
Secret Service working in the ordinary ways," Hottl wrote. His impressive 
tribute, which independently seconds the praise that Schellenberg 
offered to other cryptanalysts,' confirms the overwhelming supremacy 
that communications intelligence attained in both quantity and quality 
over almost any other form of secret intelligence in World War II. 
 
Germany's armed forces had their own agencies for cryptanalytic 
intelligence. 
Of these there were four: one in the Oberkommando der Wehrmacht 
for the armed forces as a whole, and one each for the high commands of 
the Army (O.K.H., or Oberkommando des Heeres), the Navy (O.K.M., or 
Oberkommando der Kriegsmarine), and the Air Force (O.K.L., or 
Oberkommando der Luftwaffe). All but the naval unit traced back to an 
intercept service established in the Army in 
1919 by First Lieutenant Erich Buschenhagen, who had worked in 
radio intelligence in the war. He called it the "Volunteer Evaluation 
Office." 
 
This unit stepped up its activities as Allied post-Versailles supervision 
waned in the 1920s. Part of its work consisted of picking up press 
association messages and news broadcasts and distributing a digest of 
them to government officials. By 1926, it had intercept stations in six 
major cities of Germany. In 1928, it began following the military 
maneuvers in which neighboring countries were once again engaging. It 
sneaked its intercept units into the demilitarized zone along the Rhine by 
disguising them as technicians for the German broadcasting or postal 
organizations. Much of its success resulted from traffic analysis—in 35 of 
the 52 major maneuvers between 1931 and 1937, the foreign forces were 
reconstructed completely. But it also solved some cipher systems. 
When in 1934, Hitler pointed Germany toward its eventual war of 
revenge and conquest, he swelled the ranks of the armed forces and 
intensified military activities. But though the cryptologic agencies 
likewise grew in size, they did not necessarily grow in effectiveness. There 
were too few specialists in this recondite field to fill the need created by 
the proliferating military and party organizations. Some of the Army 
cryptanalysts were siphoned off to serve in the Forschungsamt, others, 
the Luftwaffe. Some of the intercept people moved over to Josef Goebbels' 
Ministry of Propaganda, where their news-eavesdropping could help. 
About 1937, the O.K.W. created its own communications and cryptologic 
staff, thereby draining off more of the experts and further splintering the 
effort in the field. These new agencies were staffed by World War I 
veterans who were now rejoining the German Army; most had been 
officers in the signal corps but had no great exprience in or aptitude for 
intercept or cryptologic work. By mid-193 9, the German 
communications-intelligence services had 18 times as many people in 
them as they had had in 1932, but useful results had in no way kept 
pace. 
Six days before Hitler fell upon Poland, Major General Erich Fellgiebel, 
52, who had been in communications since he joined a telegraph 
battalion upon enlisting in 1905, was named head of the O.K.W. 
communications organization. His title was Chef , 
Wehrmachtnachrichtenverbindungen 
("Chief, Armed Forces Signal Communications"), or Chef W.N.V. His 
superior was the O.K.W. chief, Field Marshal Wilhelm Keitel, whose only 
superior was Hitler. Keitel wrote in FellgiebeFs fitness reports: "In his 
field a pronounced leader type with foresight, a gift for organization, full 
energy and dedication. ... In his attitude towards National Socialism an 
inclination to unconsidered over-criticism. ..." The W.N.V. supervised 
communications, including communications security, and intercept 
operations;* it served as a kind of staff, an advisor and controller, for the 
service branches that largely operated the communications and intercept 
networks for the Army, Navy, and Air Force, much as the O.K.W. itself 
advised and directed the service commands. 
Under the Chef W.N.V. came the Amtsgruppe W.N.V. Its chief was 
Major General Fritz Thiele, 48, a close colleague of Fellgiebel's who had 
previously headed the O.K.H. communications and intercept 
organization. He became Chef, Amtsgruppe W.N.V. the day the war 
began. The unit comprised radio and wire branches, which maintained 
communications between the headquarters of the three armed forces 
high commands, a technical equipment office, an administrative office, 
and the Chiffrierabteilung ("Cipher Office"), usually abbreviated "Chi." 
Colonel Siegfried Kempf assumed command of Chi on the same day that 
Fellgiebel became Chef W.N.V. Then 43, he was a career communications 
officer, a martinet disliked by his subordinates. He was succeeded in 
October, 1943, by Colonel Hugo Kettler , 48, who had had considerable 
intercept experience and who brought out the best in his men. 
In 1944, the Chiffrierabteilung was divided into eight groups. Four 
came directly under Kettler; the other four were combined into two 
supergroups, Gruppen II and III into Hauptgruppe A for cryptography, 
Gruppen IV and V into Hauptgruppe B for cryptanalysis, each with its 
own head who reported to Kettler. This was the organization: 
 
Gruppe Z (Zentralgruppe): personnel; pay, administration; office 
space and furnishings; Nazi ideological supervision. 
Gruppe I: Organization and Control. Referat la: di- 
*The term "Nachrichten" reflects this, since it means not only 
"communications" or "signals" but also "intelligence." In 
nonmilitary contexts, it means "news" or "information." 
rection of the international monitoring service (Chi had 
intercept posts in Madrid and Seville as well as Lorrach and 
Tennenlohe, with main posts in Lauf and Treuenbrietzen). Referat 
Ib: study of foreign communications systems. Referat Ic: provision 
of teletype communications for Chi and R.S.H.A./VI/MH (former 
Abwehr). 
Gruppe II: Development of German Cipher Methods and Control 
of Their Use. Referat Ha: camouflage methods for telegraph and 
radio messages; intercept and wiretapping techniques; 
cryptographic policy; supervision of cipher employment; 
cryptographic compromises. Referat lib: development of German 
cipher systems (camouflage methods, secret writing, secret 
telephony); supervision of and instruction in cipher production. 
Referat He: cryptographic systems for radio agents. 
Gruppe III: Cipher Supply. Control of production, printing, and 
distribution of ciphers and keys; operation of the distribution posts 
(headquarters at Dresden with depots in Halle , Zwickau, Chemnitz, 
Leipzig, Frankfurt -am-Oder, Bischofswerda, Magdeburg, and 
Reichenbach). 
Gruppe IV: Analytical Cryptanalysis. Referat IVa: testing of 
suggested German military cryptosystems and telephone 
scramblers for resistance to crypt-analysis: examination of 
inventions. Referat IVb: development and construction of 
cryptanalytic apparatus for Wehrmacht cryptanalytic units; 
operation of the equipment at Chi. Referat IVc: development of 
cryptanalytic methods; stripping of superencipherments for 
Gruppe V. Referat IVd: instruction. 
Gruppe V: Practical Cryptanalysis of the Messages of Foreign 
Governments, Military Attaches, and Secret Agents, Referat V 1-22: 
national offices. Referat Va: Wehrmacht codewords. 
Gruppe VI: Interception of Broadcast and Press Messages. 
Referat Via: radio reception technique; administration and control 
of the listening posts at Ludwigsfelde, Husum, Munster , and 
Gleiwitz. Referat VIb: interception of radioed press and teletype 
transmissions and of international radio traffic. Referat Vic: 
surveillance of transmissions from 
DUEL JN THE ETHER:  1      235 
within Germany to the outside. Referat VId: evaluation of 
broadcasts and press communication; issuance of the Chi-
Nachrichten (a 10- to 20-page daily summary of the non-
cryptographic intercepts); special reports. 
Gruppe VII: Referat Vila: evaluation and distribution of output. 
Referat Vllb: chronicles of events (perhaps serving as an 
information unit). 
 
In addition to these eight sections, a working committee for the testing 
of German cryptographic security reported directly to Kettler, and half a 
dozen intercept companies worked for Chi. The office was expected to 
maintain liaison with the communications units of the Army, Navy, and 
Air Force; with the chief of army equipment and commander of the 
replacement army, under whom there was an inspector of signal troops; 
with the R.S.H.A., the Foreign Office, the Propaganda, Post, Air, Trade, 
and War Production ministries and, of course, with the party. 
(By 1945, the Chiffrierabteilung had been reorganized into seven 
groups, with functions apparently as follows: Gruppe Z, administration; 
Gruppe I, organization and control; Gruppe II, Chi-Nachrichten; Gruppe 
III, broadcast and press interception; Gruppe IV, cryptanalysis; Gruppe 
V, teletype for Chi and R.S.H.A./VI/Mil; Gruppe X, evaluation, 
distribution and information services. This downgrading of cryptanalysis 
and upgrading of the non-cryptanalytic results may reflect a drop in the 
cryptanalytic results late in the war.) 
Chief of Hauptgruppe B, in which the cryptanalytic functions reposed, 
was Ministerial Counselor Wilhelm Fen-ner, 48 when the war started. A 
German born and raised in St. Petersburg, he had headed German 
military cryptanalysis since 1922. He was a brilliant organizer who 
oversaw the expansion of the group from a handful to more than 150, 
but he handicapped himself by his egocentricity and by his 
superciliousness with regard to the noncrypt-analytic aspects of 
communications intelligence. His right-hand man was a Russian 
emigrant, Professor Novo-paschenny, who under the Czar had been 
attached to an astronomical observatory in Pulkovo, outside St. 
Petersburg. He developed much of the technical aspects of the work, but 
seems to have held only a relatively subordinate post 
as a chief cryptanalyst in one of the national offices, ap parently 
Referat V 9, which was probably Russia. 
Head of Analytical Cryptanalysis (Gruppe TV) was Dr. Erich 
Hiittenhain, who also directed that group's instructional activity (Referat 
IVd). Referat IVa, which tested German cryptosystems, frequently with 
mathematical tools to calculate theoretical limits of security and to find 
improvements, was headed by mathematician Dr. Karl Stein , who held 
the rank of lieutenant, surprisingly low for so lofty a position. Referat 
IVb, headed by Engineer Wilhelm Rotscheidt, used tabulating machines 
and special-purpose devices. It invented the prototype of the translucent-
sheet-and-light device used by Pers z to strip additives from a known 
code. The unit first worked out the device for two-digit codes and then 
extended it to four. Instead of punching out holes corresponding to the 
most frequent groups, however, Referat IVb marked them with small 
crosshatched disks, and looked, not for the brightest spot, but for the 
darkest. Stein's mathematicians extensively investigated the question of 
how a codegroup stock could be constructed so that this method would 
not work against it. Referat IVc's chief was Professor Dr. Wolfgang Franz, 
and Ministerial Counselor Dr. Victor Wendland was head of Gruppe V 
(Practical Cryptanalysis) and so Fenner's immediate subordinate. 
Early in the war, the O.K.W. cryptanalysts worked in a former town 
house on one of the streets that run off the Tirpitzufer, not far from 
O.K.W. headquarters on the Bendlerstrasse. About 1943 they moved to 
much larger quarters in a modern semicircular concrete office building at 
56 Potsdamerstrasse called the Haus des Fremden-verkehr—a name that 
gave rise to many bad jokes because "fremdenverkehr" ("tourist traffic") is 
German slang for "fornication." 
On July 21, 1944, Fellgiebel's sudden removal from command rocked 
the whole W.N.V. It seemed to be connected with the bomb attempt on 
Hitler's life of the day before—and it was. Fellgiebel, whose anti-Nazi 
proclivities had been noted in his fitness report by Keitel, had in fact 
been a key figure in the plot. He was replaced by Thiele, who became 
head of both the O.K.W. and the O.K.H. agencies. He served for exactly a 
month. Then he was arrested as a co-conspirator, his personnel file 
crossed out with a giant X, and the entry made under his 
name, "stricken from the honor roll of the German Army and the 
Wehrmacht!" Fellgiebel had been executed on August 10; Thiele soon 
followed. Lieutenant General Albert Praun took Thiele's place in both 
offices and retained them to the end of the war. 
The oldest, most experienced, and closest to O.K.W. of the other 
cryptanalytic agencies was the Army's Heeres-nachrichtenwesens ("Army 
Communications System"), or H.N.W. The Chef, H.N.W., served on the 
Army general staff. Like the U.S. Army's Signal Corps during World •War 
II, it had both communications and intercept-cryptanalysis duties; like 
the Signal Corps, it turned over its solutions to Army intelligence for 
evaluation and use. 
Under Chi's watchful eye, it issued cryptosystems for the troops. For 
high-level communications, from the O.K.H. down to regiments, the Army 
used the glowlamp Enigma cipher machine. It was reliable, working well 
in the Russian winter and the Libyan summer. Signal officers thought it 
cryptanalytically secure if—as ordered by 1942 —keys were changed 
three times a day. Its chief disadvantage was that it did not print its 
output. Battery-powered and portable, it could be operated in a moving 
truck and was well adapted to radio work. 
Nevertheless, in 1943 a new machine began replacing it in some 
areas. This was a printing machine, produced by the Wanderer Werke  
firm, which copied the Hagelin variable-gear principle. There is a story 
that one of these was found in Norway at the end of the war with a 
message still in it, obviously abandoned by an operator who disagreed 
with what he had deciphered: Der Fuehrer ist tot. Der  Kampf  geht welter. 
Doenitz ("The Fiihrer is dead. The war goes on, Donitz"). 
For wire teletypewriter communications from the O.K.H. to army 
corps and a few divisions, the Germans used an on-line machine 
produced by Siemens & Halske Aktien-gesellschaft. Its heart was a set of 
ten keywheels, similar to those on a Hagelin machine, rimmed with pins 
that could be made either operative or inoperative. Each wheel had a 
prime number of pins, ranging from 47 on the smallest to 89 on the 
largest. Five of these wheels enciphered the five teletypewriter pulses, 
transforming a mark into a space or vice versa if the pin then in position 
was operative, or leaving the pulse unchanged if it was inoperative. The 
other five wheels effected a transposition 
of the pulses. The machine enciphered and transmitted in a single 
operation, and likewise deciphered and printed out the message 
automatically. 
Beginning in June, 1942, regiments, battalions, and companies 
enciphered with the double transposition, with the same keyword for 
both blocks—the same system, interestingly, as the German Army used 
at the start of World War I. (This system also backed up the Enigma.) 
Each division produced at least three keys for its subordinate units. The 
troops heartily disliked the double transposition, however, and cleartext 
messages showed a noticeable upsurge. For intelligence and combat 
reports, these units used small three-letter or three-digit codes, which 
were likewise published by their divisions. Many cipherers preferred their 
simplicity to the complexity of the double transposition, and often used 
them for orders and other unauthorized messages. A signal officer 
complained bitterly of this practice: "Tarntafeln sind kein 
Schlusselersatz!" ("Code tables are not cipher substitutes!"), he wrote in a 
report. Later in the war, a bigrapic substitution replaced the double 
transposition as a front-line cryptosystem, and in 1944 a modification of 
the grille replaced that. In addition, the signal troops used numerous 
special ciphers—for call-signs, numbers, and so on. 
The H.N.W. communications-intelligence service operated as a 
separate organization within an army or an army group, though parts of 
it were sometimes specially assigned. In 1943, for example, the 
commander of Fernmeldeaufklarung 7 ("Radio Intelligence 7"), reported 
to Field Marshal Albert Kesselring. Fernmeldeaufklarung 7 consisted of 
radio intelligence companies and platoons and direction-finding stations 
widely scattered over the central Mediterranean area—in western Crete, 
southern France, northern Africa, Sicily, Sardinia, and Italy. These units 
reported their intelligence results via their own radio net to the 
headquarters at Rocca di Papa, south of Rome; the original intercepts 
were then forwarded to headquarters for more comprehensive evaluation. 
Fernmeldeaufklarung 7 distributed radio intelligence of tactical 
importance to the lower commands by broadcasting it in a special cipher. 
While much of this intelligence came from conversations or radio 
messages in plaintext or from traffic analysis, much also came from 
cryptanalysis. 
German  Army cryptanalysts  solved  American  M-209 
DUEL  IN   1MB tlHKK:   1       LS-j 
messages almost from the days late in 1942 when the two armies first 
clashed in North Africa. They picked up such tidbits of information as 
that the 72nd, 45th, and 29th Light and the 71st Heavy Anti-Aircraft 
Regiments were placed under the 52nd Anti-Aircraft Brigade, which is 
part of the order-of-battle intelligence basic to a field commander, that on 
April 1, 1943, the 3rd Infantry Regiment was located at grid square 
43835, or 37 kilometers from Gafa, that American forces were forbidden 
to fire upon airplanes unless the airplanes attacked them (to prevent 
shooting down Allied planes). All these details were fitted together to give 
the German command a picture of the troops facing them, their state of 
mind, their preparation. 
Occasionally, a single solved message produced strikingly dramatic 
results. During a conference at the headquarters of the Commanding 
General, Southwest, in 1943, Colonel Karl-Albert Miigge, commander of 
Fernmeldeaufklarung 7, brought Field Marshal Kesselring a British 
intercept that had just been cryptanalyzed. It reported that in North 
Africa several troop columns were caught in a traffic jam of their own 
making by crowding into a wadi at—and here the cryptogram was 
garbled so that the exact location could not be read. Kesselring called for 
an immediate air search; the jammed wadi was discovered while the 
Germans were still in conference. Kesselring promptly ordered an air 
attack, which wreaked considerable destruction upon the concentrated 
British forces. 
Early in February, 1944, during the Italian campaign, the American 
5th Army attempted to recapture the Car-rocetto factory, a pivotal point 
which the Germans had taken in a counterattack. "It was important for 
VI Corps not only to regain the Factory area but also to effect the relief of 
at least a major part of the I Division," the 5th Army historian wrote. 
"Aided by the 191st Tank Battalion, men of the 1st Battalion made their 
way into the Factory in the afternoon, only to be driven out. Though our 
artillery and tanks converted the buildings into a blazing mass of ruins , 
the enemy held; prisoners reported that an intercepted radio message 
had given them foreknowledge of the attack. Another attack before dawn 
on the 12th likewise failed, and the 45th Division gave up the effort to 
regain the Factory." 
As the Allies gained air superiority and the Germans could no longer 
reconnoiter by air, they depended more 
and more on radio intelligence. This was especially true after the 
Normandy invasion. But this means was not omniscient. In the fall of 
1944, when General George Patton's army was preparing to bite out the 
fortress of Metz, the German forces detected his preparations, largely 
through radio. "Yet," wrote a German staff officer, "the actual attack on 8 
November came as a surprise to the front line troops." 
In the field, the German Army's communication intelligence unit 
worked closely with the Luftwaffe's Funkauf-klarungsdienst ("Radio 
Reconnaissance Service"). This was the intelligence side of the Air Force's 
Nachrichten-Verbindungswesen, or N.-V.W. ("Intelligence and Signal 
System"), whose chief served on the staff of the O.K.L. He also prescribed 
secret communications systems for the Luftwaffe. Air-to-air 
communications, which were mostly by voice, employed simple 
codewords to disguise unit names, much as American pilots referred to 
one another as EASY RED or GREEN ARROW in the style made familiar by war 
movies . Air-ground communications were encoded in small three-digit or 
three-letter codes. Luftwaffe ground-to-ground cryptography used the 
Enigma. 
The Funkaufklarungsdienst employed more than 10,000 men. Its 
largest subdivision was Luftnachrichten ("Air Intelligence") Regiment 351, 
with 4,500 men, which intercepted, solved, and evaluated the radio 
traffic of Allied light and heavy bombers, fighters, transports, and air 
staffs in Western Europe. An additional unit of 1,000 provided further 
detailed information on the heavy bombers. Smaller regiments covered 
other theaters. Luftnachrichten Battalion 350, with 800 men, served as 
the Luftwaffe center for basic cryptanalysis and traffic analysis, as well 
as for the study of new enemy radars and radio navigation systems to 
find the best means of jamming or deceiving them. It also covered the 
Allied transatlantic air transport service. It was attached to the main 
headquarters of the Funkaufklarungsdienst. 
Other cryptanalysts served in outlying Funkaufklarungsdienst units, 
solving messages in systems whose basic solution had been worked out 
at headquarters. They had reportedly tried to use women in teams for 
solving a widely used Allied air-ground system, called SYKO, but switched 
to male students when the women did not produce satisfactory results. 
They tested the youths by crossword puzzles 
JJUJiL IN THE hi 1 HER:  1      241 
and sent the 10 per cent doing the best to a training school for about 
a month. Here they were trained in SYKO cryptanalysis and nothing else. 
As an incentive, the Nazis told the trainees that the lower 90 per cent of 
the class would be shipped off to the Russian front. 
It was probably not SYKO that enciphered the message that gave the 
Funkaufklarungsdienst one of its greatest triumphs, since the message 
originated in a high-echelon ground command and was directed to other 
ground commands, while the planes themselves maintained radio 
silence. These were 178 four-engined Liberators, heading for the 
Rumanian oil fields at Ploesti, Hitler's chief source of oil for his thirsty 
war machine, in one of the longest-range and potentially one of the most 
important air strikes of the war. As they lumbered into the air at Bengazi 
on the morning of August 1, 1943, for their 1,200-mile flight, the 9th Air 
Force spread a short message to Allied forces in the Mediterranean area 
announcing that a large mission was airborne from Libya. This was 
necessary because only a few weeks before, in the invasion of Sicily, the 
U.S. Navy had shot down dozens of American troop planes in the 
tragically mistaken belief that they were German bombers. 
The message was picked up by a Funkaufklarungsdienst unit recently 
posted near Athens. Soon its cryptanalysts had reduced it to plaintext. 
Lieutenant Christian Ochsen-schlager then passed to all defense 
commands "interested or affected" a message stating that a large 
formation of four-engined bombers, believed to be Liberators, had been 
taking off since early morning in the Bengazi area. This gave the 
antiaircraft defenses at Ploesti, the heaviest in Europe, plenty of time to 
get ready. When the bombers roared at derrick -top height over the 
Rumanian oil field, with its wells, refineries, and tanks, they were met 
with the worst flak encountered by American bombers during the war. Of 
the 178, 53, or almost every third plane, were downed, and dozens of 
Americans died. 
The German cryptanalytic agency that probably had the greatest effect 
upon the course of the war was also the smallest and least known. It 
belonged to the O.K.M., and Grand Admiral Karl Donitz, commander of 
the German Navy during the latter half of the war, called it his "B-
Dienst," for "Beobachtung-Dienst" ("Observation Service"). The B-Dienst 
had little contact with the other codebreaking agencies. Yet its successes 
were more far- 
reaching than any of theirs, and it participated in some of the most 
unusual activities of the cryptanalytic war. 
Stung in the 1920s by revelations of Room 40's readings of German 
naval traffic, the O.K.M. built up so effective a cryptanalytic unit that by 
the start of World War II the B-Dienst had solved some of the most secret 
Admiralty codes and ciphers. The penetration of British naval messages 
enabled German surface raiders to elude the British Home Fleet, spared 
German heavy ships from many a chance encounter with stronger 
British forces, permitted surprise attacks on British warships, and 
helped sink six British submarines in the Skagerrak area between June 
and August of 1940. 
Perhaps its greatest feat came in the Norway invasion. On March 1, 
Hitler approved the plan to invade Norway, but set no date for it. Soon 
thereafter, the B-Dienst solved British naval messages that revealed a 
British plan to mine the entrance to Narvik, far in the north of Norway, 
and to occupy that port; Britain intended to block German ore 
shipments. This information enabled the German high command to 
shape a strategy for surmounting the greatest difficulty in its Norway 
invasion: how to move its weakly guarded transports from Germany to 
Norway without interference by the powerful British fleet. When the 
British Narvik expedition was under way, the high command plotted, 
Germany would send out a decoy force which the British would think 
was heading to attack their expedition at Narvik. To protect it, Britain 
would send the rest of its naval forces away to the north. As soon as this 
happened, the transports would cross the Skagerrak without fear of 
major sea attack. 
The scheme worked to perfection. Late in March the B-Dienst showed 
British vessels en route to Narvik. On April 2 Hitler set the invasion for 
the 9th. The decoy force put out to sea and was spotted on the 7th by the 
British. As the Germans expected, the Admiralty ordered the Home Fleet 
and the 1st and 2nd Cruiser Squadrons to head for Narvik. As they raced 
away from where the action was, the German transports completed their 
voyage undisturbed by the nation that supposedly rules the waves and 
landed their occupation troops without a hitch. Even Winston Churchill 
admitted that Germany had "completely outwitted" Britannia . 
The B-Dienst may have gained a great deal of help 
from some spectacular coups by the German merchant raider 
Atlantis . This specially fitted high-speed freighter, whose heavy 
armament was carefully camouflaged, was one of several that cruised the 
oceans and harassed Allied shipping. On July 10, 1940, in one of her 
first actions, Atlantis fired a few shots into City of Baghdad in the Indian 
Ocean and captured the vessel almost intact when her crew hastily 
abandoned ship. A boarding party reached the officers' cabins just in 
time to point a pistol at the captain and stop him from throwing 
overboard most of the ship's secret papers. Among them was the Allied 
Merchant Ships' Code, a two-part code issued by the Admiralty for 
messages via the Broadcasting for Allied Merchant Ships, or BAMS, 
commonly called the "BAMS code." 
Also recovered were several superencipherment tables, though not the 
current ones. Atlantis, however, had aboard in her special crew a wireless 
operator named Wesemann who had served for three years in one of the 
German cryptanalytic services. Wesemann achieved what might be the 
first nautical cryptanalysis on record when, on the basis of the captured 
code and several merchant messages that he had intercepted, he 
succeeded in reconstructing about one third of the superencipherment 
table then in use. As a result, Atlantis could read much of the Allied 
merchantmen's traffic and could await her victims at likely spots. 
When the tables were changed, Wesemann partially reconstructed the 
new ones with the help of some messages found in the wastebasket of 
the radio shack of another captured vessel, Benarty. The work was 
completed for him by the B-Dienst, which deduced from his radio queries 
that he had obtained the BAMS code and consequently sent him the 
interpretations he needed. Since Atlantis and Berlin were then almost at 
antipodes from one another, this must rank as the longest-distance 
cryptanalytic collaboration known. A few months later, on November 11, 
1940, the crew of the German raider found aboard Auto-medon, the 13th 
ship she had sunk, another copy of the BAMS code and 
superencipherment tables 7, 8, and 9. All the cryptanalyzed information 
contributed to Atlantis' record as the war's deadliest sea raider. 
She may have sent the B-Dienst photographs of the captured 
codebooks when one of her prize ships returned to 
^*»       THIS 
Germany, or the B-Dienst may have obtained a copy elsewhere. Either 
way, the German knowledge of merchant messages vastly improved U-
boat attacks. And, wrote Churchill, "The Battle of the Atlantic was the 
dominating factor all through the war. Never for one moment could we 
forget that everything happening elsewhere, on land, at sea, or in the air, 
depended ultimately upon its outcome ." More than once, the B-Dienst 
placed in the hands of the U-boat commanders the knowledge that 
brought them to the edge of victory. 
In 1941, for example, the B-Dienst read messages to convoys from the 
Commander in Chief, Western Approaches, that directed those convoys 
from the danger zones just west of the British Isles. With this 
intelligence, the U-boat command had no difficulty in deploying its 
submarines to the maximum effectiveness. Allied losses mounted steeply. 
In March, April, and May, U-boats sank 142 vessels, or more than one 
every 16 hours. In January and February of 1943, the B-Dienst mastered 
British naval cryptosystems so fully that it was even reading the British 
"U-Boat Situation Report," which was regularly broadcast to the 
commanders of convoys at sea, telling them the known and presumed 
locations of U-boats! "These 'Situation Reports' were of the greatest value 
to us in our efforts to determine how the enemy was able to find out 
about our U-boat dispositions and with what degree of accuracy he did 
so," wrote Admiral Donitz. 
The following month, March of 1943, saw the climax of the Battle of 
the Atlantic. And the climactic action, the greatest triumph of the U-
boats, in which they very nearly severed Britain's lifeline, stemmed 
directly from a series of B-Dienst solutions. 
The first came on March 9. A B-Dienst report gave the precise location 
of the eastbound convoy HX 228. (The HX stood for Halifax, Nova Scotia, 
assembly point for all fast convoys. Slow convoys, which started at 
Sydney , Cape Breton Island, Nova Scotia, were designated sc.) Shortly 
thereafter, the B-Dienst reported that the next fast convoy, HX 229, was 
southeast of Cape Race, steaming on a course of 89 degrees. On the 
14th, another solution revealed that a third convoy, sc 122, had received 
orders at noon the day before that on reaching a given point it was to 
steer 67 degrees. The U-boats, then operating in wolf packs of two or 
three dozen, were ordered to search for the convoys. 
On the morning of March 16, they sighted a convoy which turned out 
to be HX 229, and in the next two days, 38 U-boats sent 13 ships to the 
bottom. Meanwhile, HX 229 overtook the slow-moving sc 122, forming a 
large mass of shipping in a small space of ocean. The wolf pack nipped at 
its edges and sank eight more vessels, making a total of 141,000 tons 
sunk in the three-day battle, at a cost of only a single U-boat. Donitz 
exulted: "It was the greatest success that we had so far scored against a 
convoy." 
The Admiralty despaired. They considered abandoning the convoy 
system as ineffective, which was tantamount to an admission of defeat, 
since no alternative existed, the loss rate of single vessels being double 
that of ships in convoy. "The Germans never came so near to disrupting 
communications between the New World and the Old as in the first 
twenty days of March, 1943," the naval staff later recorded. It marked the 
darkest hour of the longest, most crucial battle of the war. And in large 
measure German cryptanalysts had cast this pall upon Britain by— 
paradoxically—throwing light upon British communications. 
 
13  Duel in the Ether:  II 
 
ITALY RELIED for her communication intelligence upon her Army and her 
Navy. The Navy's cryptanalysts formed the B section of the Servizio 
Informazione Segreto, or naval intelligence. Early in 1942, they had 
penetrated the British naval ciphers in the Mediterranean—these were so 
poor that Admiral Sir Andrew Cunningham reportedly threatened after 
the invasion of Crete to transmit entirely in clear if he were not given 
better ciphers. The Italian solution of a British scout plane report 
enabled the Italian high command to warn one of its task-force 
commanders at 6 p.m. March 27, just before the Battle of Cape Matapan, 
that the English had sighted him soon after he had put to sea. Next day 
the reading of an order to Cunningham from Alexandria made the 
Italians certain that British torpedo planes would attack. They did, and 
so prepared were the Italians that the intensity of their antiaircraft de- 
246      THE CODEBREAKERS 
fense made it almost impossible for the English to identify their 
targets or observe the results of the attack. 
The Italian Army's security and intelligence organization, the Servizio 
Informazione Militare, or S.I.M., had a large and well-organized 
cryptologic section which solved diplomatic as well as military 
cryptograms. This was its Sezione 5, headed by General Vittorio Gamba , 
an old Alpine warrior with austere features. A long-time student of 
cryptology and author of an excellent article on the subject in the 
Enciclopedia Italiana, Gamba was a noted linguist who reputedly knew 
25 languages. He came to public attention in 1911 when he translated a 
series of proclamations into Arabic during the Italo-Turkish conflict over 
Tripoli . The 50 members of Sezione 5 were housed in a large apartment 
house in Rome far from S.I.M. headquarters but connected by 
teletypewriter with it and with the extensive intercept unit, Sezione 6, 
located on the Forte Bocea, a hill behind the Vatican. Gamba's crypt-
analysts maintained close liaison with the chemical section, which 
worked with secret inks and other means of steg -anography, with the 
censorship section, and with the phototypographic section, which rapidly 
reproduced stolen documents. 
Like their O.K.W. colleagues, the Sezione 5 cryptanalysts had solved 
the military ciphers of Yugoslavia, with whom Italy's relations had been 
strained over Fiume and Trieste practically since Yugoslavia was created 
after World War I. The Germans used the solutions for a blitzkrieg from 
the north. The Italians exploited them in a crafty deception that helped 
avoid a possible debacle in the south. 
Almost up to the moment of the Axis invasion, the Italian armies that 
had occupied Albania had exposed what Churchill picturesquely called 
their " naked rear" to Yugoslavia in the north. Yugoslavia had no chance 
against the Wehrmacht, but both Axis and Allies realized that if she 
struck forcefully against the rather disorganized Italians, she could win a 
major victory, embarrass Mussolini , delay the Axis conquest, and acquire 
the munitions and supplies for a large-scale guerrilla harassment of the 
Nazi occupiers. Thus, when two Yugoslav divisions drove southward on 
April 7—one from Cetinje toward Shkoder, the other from Kosowska 
Mitrovica toward Kukes—it was regarded as a serious business. 
Especially when, by April 12, the Cetinje division had shoved the Italians 
back to the gates 
DUEL IN THE ETHER: II     247 
of Shkoder and was pummeling them with attacks of increasing 
intensity. 
At this juncture the Servizio Informazione Militare got an idea. It 
drafted two telegrams in Yugoslav military style and affixed the signature 
of General Dusan Simovic, head of the new government. One read: 
 
To the Cetinje divisional headquarters: 
Subordinate troops will suspend all offensive action and retire 
in the direction of Podgorica, organizing for defense. 
 
And the other: 
 
To the Kosowska Mitrovica divisional headquarters: 
Withdraw immediately with all subordinate troops back towards 
Kosowska Mitrovica. 
Simovic 
 
Both messages were enciphered in the Yugoslav Army system, and at 
10 a.m. on April 13, an S.I.M. station, observing all Yugoslav radio 
regulations as to wavelength, transmission times, and subordinate 
stations, contacted the two divisional stations and passed the messages, 
both of which were receipted for. The drive toward Kukes slackened 
immediately. The Cetinje division, however, requested confirmation. None 
came. 
Next morning, the confused divisional command, not having received 
any disavowal of the enciphered orders, and consequently believing that 
they were valid though incomprehensible lifted its attacks at Shkoder 
and began retreating northward. The Italians hastened to fill the military 
vacuum that was created, and marched the 10 miles from Kotor to 
Cetinje in a day. Next day the Yugoslav headquarters replied that no 
retreat had been ordered, but by then it was too late. It only told the 
Yugoslavs that their ciphers were compromised, and, unable to issue 
new ones in the fluid situation, they attempted to assure the legitimacy 
of their communications through onerous controls. Instead they gummed 
their command machinery at a time when every hour counted. A few 
days later it was all over. The S.I.M.'s fake messages had saved Italy from 
a crippling defeat. 
In a typical month during the war the S.I.M.'s Sezione 
248     THE CODEBREAKERS 
6 intercepted 8,000 radiograms. About 6,000 were considered worthy 
of study, and of these, Sezione 5 reduced 3,500 to plaintext. So great was 
the flow that General Cesare Ame, head of the S.I.M., began to publish a 
daily Bulletin I, which summarized the most significant information. Its 
three copies went to Mussolini, to the chief of the general staff, and to 
the king, through his aide-de-camp. The S.I.M. distributed other 
important solutions individually to the proper parties. 
Diplomatic traffic naturally went to Count Galeazzo Ciano , the Foreign 
Minister, whose many mentions of the solutions in his famous diary 
testify to their importance. According to the diary, Sezione 5 read British, 
Rumanian, and Turkish traffic. The Italians drank as deeply of the 
stream of that neutral's messages as the Hungarian group that worked 
for Hottl was to do. For more than two years, Turkish cryptograms told 
the Italian government of rumored Allied war plans, of Allied views, of an 
uncommitted observer's comments on Axis programs and prospects. On 
January 4, 1943, Ciano jotted in his diary: "The Duce asked me to give 
[Hans Georg] von Mackensen [German ambassador to Italy] a copy of a 
telegram the Turkish ambassador Zorlu sent to his government from 
Kuibyshev. It is a description of the Soviet situation. It seems impartial 
and quite informative. According to him, the war weighs heavily on the 
Russians, but Russia is still strong, and, in the judgment of the 
diplomatic corps in Kuibyshev, Axis stock is falling." 
Though Sezione 5 solved many cryptograms, many of its successes 
came, not from cryptanalysis, but from the S.I.M.'s theft of cryptologic 
documents. In 1941 alone, the S.I.M. obtained possession of about 50 
such items, or about one a week. Some of these probably were only 
plaintext versions of coded telegrams. But many were the codes or 
ciphers themselves, and one of them, which led to probably the greatest 
Axis communications-intelligence results of the war, was a secret code of 
the United States of America. 
 
The spy who stole it appears to have been Loris Gherardi, a 
messenger in the office of the American military attaché in Rome. An 
Italian national just turned 40, he had worked for the Americans since 
about 1920. His duties included the carrying of telegrams from the 
attache's office to the Italian telegraph bureau. In August of 1941 
IN   LHK E1HKR:  II       249 
he apparently obtained for the S.I.M. the key or an impression of the 
key or the combination to an embassy safe. This enabled the Italians 
surreptitiously to open the safe, remove and photograph the BLACK code 
and its attendant superencipherment tables, and then replace them. 
Neither his boss, the military attache, Colonel Norman E. Fiske, nor the 
ambassador ever suspected a thing. Loris continued on the job.* 
The BLACK code, so called for the color of its binding, was a relatively 
new and secret military ATTACHÉ code, with its own superencipherment 
tables. Ambassadors may also have used it. Thus Ciano gloated in his 
diary on September 30, 1941, shortly after the theft: "The military 
intelligence service has come into possession of the American secret 
code; everything that [U.S. Ambassador William] Phillips telegraphs is 
read by our decoding offices. . . ." 
Soon after the S.I.M. acquired the code, it gave a copy to Germany's 
Abwehr. From that moment, the Axis powers —subject only to their 
ability to strip the superencipher-ments—were enabled to peer into the 
secret messages of the diplomats and the military attaches of a great 
power that their enemies were seeking desperately to win over. And the 
messages came from all over the world, not only from Axis capitals, but 
also from Allied capitals where the American attaches had access to 
some of the most intimate secrets of the Axis' foes. "I handed 
Mackensen," Ciano noted on February 12, 1942, "the text of a telegram 
from the American military ATTACHÉ at Moscow, addressed to 
Washington. It complains about failure to deliver arms promised by the 
United States, and says that if the U.S.S.R. is not aided immediately and 
properly she will have to consider capitulating." 
But the most valuable material dealt with the battle-fronts, where the 
issue of victory or defeat was being decided. In the fall of 1941, the 
Germans were driving eastward on two fronts, Russia and North Africa, 
intending to link them up in the Near East, make the Mediterranean an 
Axis lake, march on to India, and meet the Japanese in 
*Gherardi stayed on untfl Italy's declaration of war upon the United 
States closed the embassy. After the war, he coolly asked for his old job 
back—and got it! He held it until the secret finally leaked out; then, after 
several interrogations, he resigned, in August, 1949. 
Z3U      'I tlti UUJJBBKJiAKliKS 
Asia, thereby ruling the world and fulfilling Hitler's dream of out-
conquering Alexander the Great. 
The American military ATTACHÉ in Cairo had much better 
opportunities to observe military action than his colleague in Moscow, 
owing to factors of distance, language, and politics, and he took full 
advantage of these opportunities to do his job. He was Colonel Bonner 
Frank Fellers, a West Pointer with a varied peacetime experience, 
including two years as assistant to General Douglas MacArthur. Fellers 
had been posted to Cairo in October, 1940. He industriously toured the 
battlefronts and studied the tactics and problems of desert warfare. He 
asked questions. He kept his eyes open. The British let him in on some of 
their secrets, hoping that this would improve American equipment lend-
leased to Britain's desert forces, but probably withheld some because of 
his anti-British predilections. Fellers soaked up this great quantity of 
information and poured it out to Washington in voluminous and detailed 
reports. 
He discussed the British forces at the front, their duties, capabilities, 
and effectiveness; he told of reinforcements that were expected and 
supply ships that had arrived, explained morale problems, analyzed the 
various tactics that the British had under consideration, even reported 
on plans for local military operations. He carefully encoded his messages 
in the BLACK code and radioed them to Washington, usually addressed to 
MILID WASH  (Mzfitary Intelligence Division, Washington). And as his 
transmissions flashed through the ether, listening Axis radio stations—
usually at least two, so that nothing would be missed—took down every 
word. The intercepts were transmitted by direct wire to cryptanalysts, 
where they were reduced to plaintext, translated, reenciphered in a 
German system, and forwarded to General Erwin Rommel , commander of 
the Afrika Korps. He often had the messages only a few hours after 
Fellers had sent them. 
And what messages they were! They provided Rommel with 
undoubtedly the broadest and clearest picture of enemy forces and 
intentions available to any Axis commander throughout the whole war. 
In the seesaw North African warfare, Rommel had been driven back 
across the desert by the British under General Claude Auchinleck at the 
end of 1941, but beginning on January 21, 1942, he rebounded with 
such vigor that in seventeen days he had 
DUEL IN THE ETHER: II      251 
thrown the British back 300 miles. During those days he was getting 
information like this from the Fellers intercepts: 
 
January 23: 270 airplanes and a quantity of antiaircraft 
artillery being withdrawn from North Africa to reinforce British 
forces in the Far East. 
January 25-26: Allied evaluation of the defects of Axis armor 
and aircraft. 
January 29: Complete rundown of British armor, including 
number in working order, number damaged, number available, 
and their locations; location and efficiency ratings of armored and 
motorized units at the front. 
February 1: Forthcoming commando operations; efficiency 
ratings of various British units; report that American M-3 tanks 
could not be used before mid-February. 
February 6: Location and efficiency of the 4th Indian Division 
and the 1st Armored Division; iteration of British plans to dig in 
along the Acroma-Bir Hacheim line; recognition of the possibility 
that Axis forces might reach the Egyptian frontier once the 
armored divisions had been regrouped. 
February 7: British units stabilized along the Ain el Gazala-Bir 
Hacheim line. 
 
These only highlight the outstanding tesserae of the abundantly 
detailed mosaic which Rommel had available and which helped him win 
his epithet, "the Desert Fox." And when in May of 1942 his Panzer 
divisions rolled forward in his supreme effort to conquer Egypt and 
punch through Palestine to join the Wehrmacht forces from Russia, the 
intercepted American messages again brought him information of the 
highest importance. They first told him that the British were planning to 
anchor their defense line on Mersa Matruh, a town on the Mediterranean 
coast about 200 miles west of Alexandria; then, when Auchinleck decided 
that this position was untenable, the intercepts kept Rommel up to date 
with the British changes of mind. 
But even Rommel could not do much without gasoline for his tanks 
and troop-carriers, and of this he never had enough. The thorn in his 
side was Malta. This tough little island, a British bastion lying in the 
Mediterranean between Sicily and the Axis bases in North Africa, served 
as the base from which Allied ships, planes, and submarines 
wreaked havoc on Axis convoys carrying men and supplies to 
Rommel. Thus Germany and Italy sought to batter it into submission 
with air raids night and day, while England sought to strengthen and 
arm it by driving convoys through to her port of Valletta. When the Axis 
supply line was flowing freely, Rommel scored one victory after another; 
when the Allies choked off his supply line and his tanks thirsted for 
petrol , Rommel's mobility in this highly fluid war of movement was 
seriously restricted, giving the Allies a considerable advantage. 
Hence in June of 1942 the British determined to make a large-scale 
attempt to relieve Malta. They planned to pass convoys through from the 
east and from the west simultaneously, thus preventing the Axis from 
concentrating all its might on either movement. To paralyze Italian 
surface forces, Britain heavily bombed the Taranto naval base, and to 
minimize Axis air attacks on the convoys, the British planned to destroy 
Axis airplanes just before the convoys sailed. This they would accomplish 
by bombing, by swift strikes of motorized forces on airfields near the 
front, and by sabotage from commandos parachuted onto other airfields 
deeper within the German lines. Fellers, who was in close touch with the 
situation, knew of these plans, and on June 11—the day the eastern half 
of the convoy sailed from Alexandria—he drafted message No. 11119: 
 
Nights of June 12th June 13th British sabotage units plan 
simultaneous sticker bomb attacks against aircraft on 9 Axis 
airdromes. Plans to reach objectives by parachutes and long range 
desert patrol . 
This method of attack offers tremendous possibility for 
destruction, risk is slight compared with possible gains. If attacks 
succeed British should be prepared to make immediate use all 
R.A.F. [Royal Air Force] to support coordinating attacks by army. 
Today British making heavy troop movement from Syria into 
Lybya. 
Fellers 
 
He encoded it and filed it with the Egyptian Telegraph Company in 
Cairo for radio transmission to MILID WASH. The O.K.W. intercept station 
at Lauf snatched it from the ether at about 8 a.m. June 12. By 9 a 
cryptanalyst was 
working on it to strip the superencipherment; by 10 it had been 
decrypted; by 11:30 Rommel had it in plenty of time to warn his airfields. 
On the night of the 13th, as expected, commandos dropped from the sky 
and strike forces roared in from the east. 
The waiting German and Italian forces massacred them. The carefully 
planned operation failed almost completely. At the three North African 
airports of Matruba, El Fetejak, and Barce, not a plane was touched; at 
the K2 and K3 airfields, the British succeeded only in slightly damaging 
eight craft , all of them repairable in a few days. At three other airfields 
(Benina in North Africa and Heraklion and Castelli in Crete), where the 
warnings were either not received or ignored, the British destroyed a total 
of 18 planes and burned two hangars. 
Next day, airplanes that had been saved from destruction by the 
timely warning delivered heavy attacks upon the convoy from Alexandria, 
sinking three destroyers and two merchant ships. A U-boat got a heavy 
cruiser, and when heavy Italian forces sortied from Taranto, the convoy 
turned back under this threat and the entire operation failed. "The 
approach to Malta from the eastward remained sealed, and no convoy 
again attempted this passage until November," wrote Churchill. "Thus, in 
spite of our greatest efforts, only two supply ships out of seventeen got 
through, and the crisis in the island continued." And Rommel's pipeline  
remained open. 
With his gasoline supplies assured, at least temporarily, the Desert 
Fox swept forward in the onslaught he had begun on the moonlit night of 
May 26-27. Complementing the strategic intelligence that the Fellers 
intercepts were providing was the tactical intelligence from his highly 
efficient Fernmeldeaufklarung Company under Captain Alfred Seebohm. 
This mobile outfit tuned into every British 8th Army radio station, picked 
up every scrap of chat , ascertained troop and tank concentrations and 
movements by direction-finding, learned which units were where by 
analyzing call-signs, studied British cryptograms, and in general 
provided Rommel with much of the raw data by which he could sniff out 
the enemy's intentions and then take counteraction of his own. 
During the drive to isolate Tobruk, for instance, the 
Fernmeldeaufklarung Company overheard a radiotelephone conversation 
in clear at 10:30 a.m. June 16, 1942, be- 
 
tween the 29th Indian Brigade and the 7th Armored Division. From 
this it appeared that the garrison of the El Adem box, or strong point, 
intended to attack the Germans that night. The information was passed 
to Rommel and his intrepid 90th Light Division, who attacked at once, 
catching the British so off balance that instead of their pum- meling the 
Germans, Rommel captured El Adem. This enabled him to surround and 
isolate Tobruk, which unexpectedly capitulated on the 20th, allowing 
enormous quantities of stores to fall into German hands and giving the 
daring Panzer leader his opportunity to strike immediately for Suez. It 
was aid of this sort that prompted Rommel's intelligence officer to call 
Seebohm's Fernmel-deaufklarung Company "a very important factor in 
Rommel's victories." The company could also have independently read 
the Fellers messages with a furnished copy of the BLACK code to save time 
in getting the information to Rommel. 
On July 10, the swirling desert warfare brought the Afrika Korps staff 
headquarters directly into the path of a British armored thrust. In a 
brief, fierce spurt of action, the brilliant Seebohm was killed and most of 
his unit wiped out or captured. Many of their records fell into British 
hands. This loss deprived the company's replacements of a great deal of 
necessary information, and at the same time enabled the British to 
correct many radio-security mistakes. Rommell thus lost the microscope 
that scrutinized the enemy lines and presented to him so many bits of 
information. 
At about the same time he lost his telescope. The United States 
appears to have had some suspicion of the leak earlier in the spring, 
when two officers came out from Washington to check on Fellers' security 
measures. They cleared him, and perhaps this lulled their fears until new 
information reached the Allies. Apparently a prisoner of war told the 
British of the intercepts, and the British, who had themselves broken the 
BLACK code and its su-perencipherment, using it to read other traffic, now 
began to pick up Fellers' messages within an hour after he filed them. 
After ten days of studying his "long, detailed, and extremely pessimistic" 
reports, they notified American authorities late in June of the leak and 
perhaps of Fellers' attitude. Fellers himself was never told of the German 
solutions, but was recalled to Washington, returning in 
July.* Later messages from Cairo still contained some noteworthy 
observations but no broad view of the situation. And when the new 
military ATTACHÉ there began using the M-138 strip cipher, which defied 
all Axis attempts at solution, it cut Rommel off from the strategic 
intelligence on which he had so long depended. 
The loss occurred just as he was crossing the frontier into Egypt and 
seemed to have the Pyramids and victory almost within his grasp. The 
British 8th Army fell back to its fortified positions at El Alamein , and on 
July 2 Auchin-leck jabbed out with the first of a series of counterattacks. 
Rommel, deprived of his most valuable source of information, could no 
longer take the expeditious measures for defense and offense that he was 
previously enabled to. On July 4, he reported that he was going over to 
the defensive. Meanwhile, Britain succeeded in reinforcing Malta, and 
attacks from there pinched the Axis pipeline. Rommel clamored in vain  
for fuel. 
At the same time, the 8th Army built up a powerful force in secrecy, 
and concealed not only the date but the direction of its main thrust. Two 
divisions arrived with 240 guns and 150 tanks. In the old days, the 
Afrika Korps would have learned of it from Fellers' messages; this time 
they never knew the two were there. The British had profited from their 
capture of the Fernmeldeaufklarung files to institute an improved call-
sign procedure, tauten cryptographic discipline forward of divisional 
headquarters, introduce radiotelephone codes, impose rigid wireless 
silence or reserve formations, pad out real messages with dummy traffic, 
and create an entire fake signals network in the southern sector. The 
new Fernmeldeaufklarung staff had neither the talent nor the experience 
to penetrate these disguises and sift the true from the false. The 
Germans, who had been used to the constant flow of information from 
Seebohm's men, had to depend almost exclusively upon ah" 
reconnaissance, without any radio-intelligence corrective. And 
camouflage fooled it Hundreds of tanks and guns were hidden beneath 
dummy trucks; large supply 
*Later in 1942 he was awarded the Distinguished Service Medal for 
his work as military attach ^, which "contributed materially to the tactical 
and technical development of our Armed Forces." The citation also stated 
that "His reports to the War Department were models of clarity and 
accuracy." 
depots were created so slowly in the south that it looked as if they 
could not be ready for several months. 
So when General Bernard Montgomery opened fire with a thousand 
cannon on the German positions at Alamein on October 23, it came as a 
complete surprise to the Afrika Korps. Rommel had been so certain that 
nothing would happen for a while that he had gone to Austria to 
convalesce. He flew back at once to take personal charge of the battle, 
but by the time he arrived it had already been lost. Hampered by 
shortages of oil, men, and armor, he could only shift his divisions about 
in desperate but futile attempts to recover. The defeat became a rout, 
and the Afrika Korps fled west across the desert, leaving a battlefield 
littered with hundreds of destroyed or useless tanks and troop-carriers. 
A few months later the Germans were driven out of Africa, then out of 
Crete, then up the boot of Italy—always retreating, never again 
advancing. The Battle of Alamein marked the turning of the Allied hinge 
of fate. "Before Alamein we never had a victory," Churchill said. "After 
Alamein we never had a defeat." 
That change in fortune had revolved, to no small degree, upon 
cryptology. 
 
Almost certainly the best of the nonbelligerent cryptanalysts, and 
perhaps one of the best in the war, was that of the precarious neutral, 
Sweden. At first she used code-breaking primarily to see whether Hitler 
planned to grant her the same sort of military protection that he so 
generously accorded Norway and Denmark. His preparation for 
occupying those two countries was one of the best-kept secrets of the 
war, and Sweden did not want to be caught napping. Later she used the 
intelligence to keep abreast of a variety of political events. 
Except for a brief interlude back about the turn of the century, when 
R. Torpadie so impressed the Swedish authorities by solving a 
nomenclator of 1632 for a historical study that they commissioned him 
to set up a cryptologic bureau called Room 100, Swedish cryptology got 
its real start with Yves Gylden. His father, Olof, the head of the Royal 
Naval School, had been financially interested in Arvid Damm's cipher 
machines. Yves, who got his un-Swedish first name from his French 
mother, became cryptologically interested and subjected them to every 
possible cryptanalytic test The interest thus kindled 
in cryptology remained with him throughout a business career with 
the pharmaceutical firm of Astra , founded by his grandfather . In 1931, a 
tall, grave man of 36, Gylden published his Chifferbyrdernas insatser i 
vdrldskriget till lands, a keen, perceptive study of World War I cryptology 
and its effects. Its 139 pages were later translated into English by the 
U.S. Army Signal Corps as The Contributions of the Cryptographic 
Bureaus in the World War, and portions were published in the Revue 
Militaire Fran-false. This book demolished the lingering myth of chamber 
analysis, demonstrated the crucial role of errors and of torrents of 
ciphertext, and generally crystallized the lessons of World War I and 
catalyzed the evolution of the cryptology of today. 
Five years after the influential little book was published, Sweden set 
up a cryptologic bureau. It was headed by Colonel C. G. Warburg, a 
gentleman who had fallen off a horse , broken both arms and legs , and 
needed a sinecure. He proved as incompetent in cryptology as in 
equitation, and was replaced by a naval officer who won the respect of 
the experts who later served under him. During the late 1930s Gylde'n 
gave many talks on cryptanalysis to Swedes. He also sowed the seeds of 
a valuable cooperation With the other Scandinavian countries when he 
lectured in Oslo and stimulated Captain Roscher-Lund to set up 
Norway's first cryptologic office. In 1939, during a 12-hour war game, 
Gylden headed the cryptanalytical office that solved 38 of the 56 rather 
simple cryptograms transmitted by the "invaders." Sweden's preparations 
extended to recruiting talks at Uppsala University, where coeds were 
entertained with the intrigues of cryptology and sold on the idea that 
they could become good codebreakers. Other personnel were drawn from 
the winners of cipher-solving contests which the cryptanalysts got the 
newspapers to run. 
When war broke out, the Swedish cryptanalysts numbered 22. All 
were paid the magnificent sum of half a crown a day (raised later by 
stages to two crowns), as a result of which most of them engaged in a 
kind of part-time cryptanalysis—working for the government in the 
morning and at regular jobs to get money to live on in the afternoon. 
They were installed first in the Gray House, Sweden's Defense Ministry 
building, and afterwards in an old house at Carlaplan 4, since 
demolished and replaced 
by Sveriges Radio; they finally settled down in an old, drafty, 
noncentrally-heated apartment house at Styrmans-gatan 2. (A branch 
was also established in a modern apartment house in Strandvagen in 
1943.) 
In 1940 the cryptanalysts were divided by language, though some of 
the mathematicians shifted from group to group. The four units were: No. 
1, for Romance languages, primarily French and Italian, headed by 
Gylden, who had spent ten years in France and was fluent in that 
language; No. 2, for German, in which one of the brightest workers was 
Carl-Otto Segerdahl, a young mathematician; No. 3, for English, which 
attacked American and British systems and was headed by Dr. Olof von 
Feilitzen, 32, a librarian whose English is better than that of many 
Americans; No. 4, for Russian, headed by Dr. Arne Beurling, 35, a big, 
slow-talking, quietly handsome professor of mathematics at Uppsala 
University, who in 1952 became a member of the Institute for Advanced 
Study at Princeton. Beurling, one of the war's finest crypt-analysts, also 
determined the unknown ciphers of other countries and made the initial 
breaks. Gylden, as the founder, was a kind of first among equals; he also 
taught new recruits. These came in at such a pace that by the time he 
left in 1941 the group had grown to 500, and by the end of the war to 
1,000. 
Messages, too, poured in. Teletypewriters, cut directly into Swedish 
postoffice circuits, duplicated messages sent over those wires. Norway, 
Denmark, and Finland forwarded their intercepts to Sweden, which had 
perhaps the best cryptanalytic center among them, and these messages 
enabled Sweden to make very fruitful comparisons between the same text 
enciphered in different keys. She paid her Nordic associates back with 
the information gained in the resultant cryptanalysis—sometimes with 
valuable results. 
Early in 1940, just before the German occupation of Norway, Nazi 
agents there, who were concentrated in the German- Norwegian shipping 
lines and in the large fishing and fish-processing firms, were ordered to 
pass back information on ship movements and weather. They disguised 
the data as sales prices, offers, and tonnage reports on fishing, and 
transmitted by telephone and radio. But the Norwegian authorities had 
intercepted the telephone calls, which dealt with prices in a highly 
suspicious manner. 
They sent recordings to Sweden, where Segerdahl discovered that the 
five-digit "prices" actually represented the transposed and 
monoalphabetically enciphered numbers of ships in Lloyd's Register. The 
solutions enabled Norway to break up at least one of the rings in 
February, though others continued to operate. 
The Swedes not only used cryptology against foreign espionage, they 
sometimes used espionage against foreign cryptology. In one case, they 
tapped a telephone call between the Italian military ATTACHÉ in Stockholm 
and his colleague in Oslo. The recording sounded absolutely 
unintelligible, and the Swedes at first thought that the Italians had used 
a telephone scrambler. When they determined that they had not, the 
recording was sent to the language department at Uppsala, where it was 
found to be a Sicilian dialect rendered incomprehensible by the attache's 
over-liberal use of cursewords. Eventually the sense was sorted out, and 
the conversation proved to comprise the Stockholm attache's 
explanations of how to use the military ATTACHÉ code, which the Oslo 
man—who was railing at the idiots in Rome who would send him such a 
code—could not fathom. Between the explosions of the colorful Sicilian 
equivalents for "dunce" and "jackass" and still other expletives were 
references to operating procedure, meanings of specific codewords, and 
so on. Needless to say, it proved a great help to Gylden in his Italian-code 
solutions. 
The Swedes also obtained much help from their own Foreign Office in 
the form of diplomatic notes sent and received, reports of notes verbales, 
aides-memoires of conversations with various ambassadors, and other 
memoranda. This is common practice in all countries, but the Swedish 
cryptanalysts carried it to a peak of perfection by using as their liaison 
man a former foreign minister. Rickard Sandier, 56, had served in that 
post from 1932 to 1939; he had also filled in as premier for 18 months in 
1925 and 1926, and in 1934 had been elected president of the League of 
Nations Assembly. Spare and round-faced, Sandier had been bitten by 
the cryptology bug, and in 1943 he wrote a book on famous ciphers. But 
he proved inept as a crypt-analyst, unable to solve what the Swedes 
regarded as the simplest of practical problems—Norwegian one-part 
codes. However, he was a great success in making sure that the Foreign 
Office reported every scrap of information promptly to the cryptanalysts. 
So well did he have his contacts 
trained that the Foreign Office even reported the time of departure of 
an ambassador's car from the Foreign Office building. With this little 
datum , the cryptanalysts—knowing the message he had been given and 
estimating how long it would take the ambassador to drive to the 
embassy and have a message of that length encoded and sent to the 
telegraph office—could more easily pick out the cryptogram 
corresponding to that message from the embassy's daily file. 
As usual, the Swedish cryptanalysts were greatly helped by lazy or 
stupid encoders. Clerks repeatedly violated the most elementary rules by 
failing to superencipher and forgetting to bisect messages. The worst 
bungler the Swedes came across was the German consul at Stavanger, 
whose numerous blunders became the vulnerable heel of many a 
German message. His name—almost too fittingly—was F. W. Achilles. 
The Swedes appreciated his help so much that they hung a large 
photograph of him in their office. "He was very fat and he looked like a 
gorilla ," Segerdahl said. "I never met the man personally, but I 
considered him my best friend in the German diplomatic service!" 
The Swedes also read messages in other German systems —a double 
transposition for the military ATTACHÉ and two substitution systems for 
the troops. The latter gave them an unexpected peek into the sex habits  
of German soldiers. The Wehrmacht provided women from the Baltic 
states and concentration camps as prostitutes for the occupation forces 
in Norway, and the vessels were naturally awaited with great eagerness. 
Their arrivals and departures formed the subject of excited 
communication between units, and not infrequently a radioman in a port 
from which a ship had just sailed would recommend one of the girls to a 
fellow signalman in the port to which the ship was headed. The reasons 
were sometimes quite specific, and the Swedes came to think that they 
knew the girls almost as well by cryptologic means as the soldiers did by 
carnal. 
But errors, circular messages, and all the other aids would not have 
helped the Swedes much if they were not as clever as they were. They 
became so attuned to French procedure in regard to a multiplicity of 
codes—at one time the French had eleven in simultaneous use—that 
they could tell when the French regarded them as compromised (after 
about four years) and began sending material in them that they wanted 
others to read. Usually this tried to implant  
the idea that the French were acting only out of the most moral 
considerations in a given situation, probably to distract attention from 
their real motives. Many phrases from the messages in these 
compromised codes later showed up in the French Yellow Books, the 
official governmental statements of their positions. The Swedes also 
solved an American-British code in which U-boat warnings were 
transmitted—probably the same that Germany's B-Dienst read—and 
thus got a free ride in safeguarding their own merchantmen. 
Quiet possibly the finest feat of cryptanalysis performed by the 
Swedes, and the most far-reaching, was Arne Beurl-ing's solution of the 
German Siemens machine. Since German messages passed over Swedish 
wires just as German soldiers passed over Swedish rails, both the 
Wehrmacht in Norway and the German embassy in Stockholm took 
advantage of the machine's on-line capabilities to wire messages directly 
to Berlin. The German Foreign Office called the machine the 
Geheimschreiber ("secret writer"). The teleprinters in the Swedish 
cryptanalytic bureau rapped out the German correspondence, and it was 
given to Beurling for an attempt at solution. 
He observed at once that the ciphertext consisted of the 26 letters and 
six digits, a total of 32 characters, or 2B. This suggested a cipher based 
on a teletypewriter to him, since he knew that teletypewriters used a five-
hole punched tape. That was about all he knew, though, and he had to 
get a book on them to see how they worked. His studies— perhaps aided 
by an examination of patents—led him to the conclusion that a machine 
based on the Baudot code would encipher by shifting the positions of the 
five contacts, that each of these positions would very likely be controlled 
by a keywheel of its own, and that the number of control pins on the 
circumference of these wheels would vary from wheel to wheel to make 
the period as long as possible. 
Since the key probably changed daily, Beurling selected the traffic for 
a single day, May 25, 1940, to work on. It covered the equivalent of two 
large sheets of paper. His analysis soon showed that his preliminary 
suppositions were correct, except that the substitution of the Baudot 
pulses was followed by a transposition. Very often the transposition had 
no effect. If, for example, pulses 1 and 2 were the same, the transposition 
of 1, 2, 3, 4, 5 into 2, 
i, j, t, 3 would leave the character unchanged. Beurling took full 
advantage of these peculiarities to reconstruct the mechanism. He 
checked his work with new data from the traffic of May 27, found it was 
correct, and within two weeks of undertaking the job had solved the 
cipher. A Swedish mechanic constructed an apparatus to Beurling's 
specifications, and though it looked monstrous and made a terrific 
racket, it printed out the German messages that the Swedes wanted to 
read. 
To recover the daily keys, the cryptanalysts would work through the 
night, and in the morning, when the Swedish commander, Lieutenant 
General Olov Thornell, came in to ask, "What's the news from the 
Germans today?" they were usually able to tell him. Twice when the 
Germans made threatening moves with their troops in Norway toward 
Sweden, Swedish troops, alerted by crypt-analyzed messages, moved 
swiftly into position and blocked the Germans. Their commander, 
General Niklaus von Falkenhorst, later extended congratulations to 
Thornell on the brilliance of his tactics. Thornell passed the felicitations 
on to the cryptanalysts. 
In the spring of 1941, the Swedes cryptanalyzed other German 
military messages that, put together, spelled an invasion of Russia 
between June 20 and 25. Erik Bohem-ann, secretary general of the 
Swedish Foreign Office, passed the information to Sir Stafford Cripps, 
British ambassador to the Soviet Union, at a dinner in Stockholm while 
Cripps was passing through. This may not have come as news to Cripps, 
who may have known of the invasion from other sources, but it certainly 
reinforced any knowledge he had. Unfortunately, Stalin did not believe 
the British. 
The dozens of diplomatic messages that clattered out of the Beurling 
mechanism told the Swedish Foreign Office what the Germans were 
really doing and thinking. They gave Foreign Minister Christian Giinther 
advance warning of diplomatic notes that the German embassy was 
ordered to submit to him. The cryptanalysts tell a story that, after 
reading a particularly demanding note, they took the unusual step of 
notifying Giinther of its contents by telephone, which they rarely used. 
(Later they sent it over by the regular messenger, who wore two shoulder 
holsters.) Giinther promptly went on a "hunting trip," and the German 
diplomat could not serve his demand until after the weekend. By then 
the Swedes had formulated a policy that 
enabled them to tell the Germans, with suitable regret, that they were 
unable to fulfill the requests. 
And so Sweden's cryptanalysts helped her navigate the perilous 
waters of neutrality while all about her raged the war. 
 
Great Britain's main cryptanalytic agency lay within her Foreign 
Office, which had taken over the personnel of the Admirality's Room 40 
at the end of World War I. The Reverend William Montgomery, one of the 
solvers of the Zimmermann telegram, for example, joined the Foreign 
Office. Early in the 1920s, in a circular urging its diplomats to be more 
careful in the use of their codes, the Foreign Office told them that it was 
spending £12,000 a year, or almost $60,000, both in keeping British 
codes secret and in solving those of foreign governments, and that 
carelessness in handling codes was wasting much of this (or at least 
much of the part spent for British cryptography). The usual  legends  
circulated among the diplomats about their code experts, some of whom 
had "made a life-long study of the work." One story credited one of these 
wizards with solving a Turkish code during the war in less than five 
months, though he himself could not speak Turkish and had had to call 
in experts in the language to translate the messages. The Foreign Office 
reportedly considered no code as fully secret after it had been used for 
six months; consequently it changed all highly confidential codes every 
four months. 
In 1939, the Foreign Office moved what it euphemistically called its 
Department of Communications to Bletchley Park, an estate and 
mansion in Bletchley, a town in Buckinghamshire about 50 miles 
northwest of London. It is far and away the most history-redolent black 
chamber of all. The British, of course, trace the land from a Roman 
encampment, through its award by William the Con- querer to Bishop 
Geoffrey of Constance for services rendered at the Battle of Hastings, 
down on through the ownership of various lords (most notably the two 
George Villierses, first and second dukes of Buckingham ) and rich men 
of decreasing interest. A mansion was first built on the land in the 1870s 
and added to repeatedly; the Foreign Office, finding this too small, added 
many buildings, including a cafeteria and a large hall. Eventually 7,000 
wonced and trained there, including members of the armed services. 
 
[Codebreakers 264.jpg]
Britain urges cryptographic discipline 
 
The War Office expanded its M.I. 1 (b), the cryptanalytic agency 
started in World War I in the War Office, to M.I. 8—the same name, 
coincidentally, as that held by Yardley's organization. The Admiralty and 
the Air Ministry presumably had cryptologic agencies of their own. One of 
the first victories of the Admiralty's unit was, surprisingly, in the domain 
of cryptography. 
Since the beginning of the war, Admiralty secret com-munciations 
had been read by the B-Dienst, with such disastrous results as the loss 
of Norway almost by default. The Germans continued to listen in to 
Admiralty messages during the critical summer of 1940 as Hitler 
prepared for Operation SEALION—his invasion of England. The crypt-
analytic intelligence had long been entering into operational planning, 
and the Oberkommando der Kriegsmarine had come to depend on it. 
Suddenly, on August 20, as all England was bracing itself in its finest 
hour, and the sky above was streaked with contrails as the few earned 
their tribute from the many, the Admiralty, which had finally tumbled to 
the German cryptanalysis, changed its codes and ciphers. O.K.M. went 
deaf . The abrupt cutting off of quantities of information about British 
plans and disposi- 
tions caused, a German said, "a great setback for German naval 
strategy." No longer could German vessels strike out at the greater 
British forces with foreknowledge or move deftly out of their way. British 
sea power rapidly gained its normal ascendancy. English ships shelled 
the invasion fleet in Channel ports. Air reconnaissance alone could not 
tell the Germans enough. The O.K.M., never very warm for SEALION, 
chilled still further. Eventually its coolness spread throughout O.R.W., 
and then to Hitler. It contributed to his ultimate decision to postpone 
SEALION  indefinitely , and hence forever. 
 
[Codebreakers 265.jpg]
A British naval officer demonstrates the proper codebook security for when capture 
threatens 
 
All of Britain's cryptologic work seems to have been coordinated by 
the Foreign Office's Department of Com munications, which apparently 
handled strategic and primary cryptosystem solutions. All over the world, 
Britain had about 30,000 persons in communications intelligence. 
Deputy director of the Department of Communications was a man who 
had already made a mark in the world by his cryptanalytic efforts. He 
was Nigel de Grey, who in 1917 had solved the Zimmermann telegram. 
The department turned out solutions at a fairly rapid 
I 
rate. On November 21, 1941, a Japanese diplomatic solution was 
given number 097975; on December 12, another Japanese diplomatic 
solution was numbered 098846;— indicating almost 300 solutions a 
week at that time (not Japanese alone, of course). A typical distribution 
of these solutions would send three copies each to the director of the 
department, the Foreign Office, and the War Office, two to the India 
Office, and one each to the Admiralty, the Air Ministry, the Colonial 
Office, the Dominion Office, M.I. 5 (counterintelligence), and Sir Edward 
Bridges, secretary to the Cabinet. The appearance of Bridges' name on 
the list suggests that some of the British intercepts may have been read 
aloud at Cabinet meetings. In addition, Churchill, on August 5, 1940, 
ordered that a daily selection of original intelligence documents be 
submitted to him personally "in their original form," which almost 
certainly included intercepts. Much of the cryptanalytic output must 
have gone to the Joint Intelligence Committee, which evaluated all 
intelligence. It was always chaired by a Foreign Office representative, who 
was Victor F. W. Caven- dish -Bentick throughout most of the war, and 
included the directors of military, naval, and air intelligence. 
The intelligence from these solutions went also to the United States, 
but so closely did Britain guard her crypt-analytic capabilities that for 
more than a year she would give the United States information based on 
the crypt-analyses but would not name the source. In January, 1941, 
however, a four-man American cryptanalytic mission accompanied a 
PURPLE machine to England to establish technical cooperation with 
British cryptanalysts. Britain had not cracked the PURPLE machine, but 
they had more in the way of cryptanalyzed intercepts than the United 
States, and this was the quid pro quo. This cooperation between the two 
English-speaking nations in the most sensitive of areas tells the depths 
of their friendship. The American Signal Intelligence Service and OP-20-G 
radioed the PURPLE keys to London daily. Cooperation extended to the 
small Australian communications-intelligence unit and to the unit at 
Singapore, and Canada assisted in making sure that all got all Japanese 
intercepts. 
 
Among the characteristic features of World War II was the extensive 
use of codenames to designate important operations or secret projects. 
Codenames had been used 
before—the words "tank" and "blimp" themselves derive from World 
War I codenames—but never so frequently. They aimed both at security 
and brevity: obviously it was easier to say "Operation TORCH" than "the 
Anglo-American invasion of North Africa," and solvers of any messages 
would still have to determine the meaning of the code-names. 
Selection and assignment of the codenames was, in the United States, 
a duty of the Current Section of the Army's Operations Division. Men of 
the unit culled the unabridged dictionaries for suitable words—chiefly 
common nouns and adjectives that did not imply operations or localities. 
They avoided, as confusing, personal and ships' names and geographical 
terms. Of the dictionaries' 400,000 words, they compiled about 10,000 in 
scrambled order in a classified book. They cross-checked these to 
eliminate any conflicts with British codenames. Then they assigned 
blocks of codenames to theater commanders. 
In theory the codenames bore no relation, either by denotation or 
connotation, to what they stood for. In the majority of cases this held in 
practice. FLINTLOCK meant the Allied attack on the Marshall Islands in 
1944; AVALANCHE, the amphibious attack on Salerno ; ANVIL, later 
DRAGOON, the Anglo-American landings in the soft underbelly of France. 
Even relatively small operations were dubbed: the relief of Australians 
trapped in Tobruk was SUPERCHARGE, the occupation of the Canary  
Islands was  PILGRIM . Some codenames were written in blood : OMAHA, 
UTAH, GOLD, SWORD, and  JUNO , for the Normandy beaches of D-Day. 
The allied codename selections were sometimes constrained by 
principles that that master of English, Winston Churchill laid down in a 
memorandum of August 8, 1943: 
 
I have crossed out on the attached paper many unsuitable 
names. Operations in which large numbers of men may lose their 
lives ought not to be described by code-words which imply a 
boastful and overconfident sentiment, such as "Triumphant," or, 
conversely, which are calculated to invest the plan with an air of 
despondency, such as "Woebetide," "Massacre," "Jumble," 
"Trouble," "Fidget," "Flimsy," "Pathetic," and "Jaundice." They 
ought not to be names of a frivolous character, such as 
"Bunnyhug," "Billings- 
gate," "Aperitif," and "Ballyhoo." They should not be ordinary 
words often used in other connections, such as "Flood," "Smooth," 
"Sudden," "Supreme," "Fullforce," and "Fullspeed." Names of living 
people —Ministers or Commanders—should be avoided, e.g., 
"Bracken." 
2.  After  all,  the  world  is  wide,   and  intelligent thought will 
readily supply an unlimited number of wel-sounding names which 
do not suggest the character of the operation or disparage it in any 
way and do not enable some widow or mother to say that her son 
was killed in an operation called "Bunnyhug" or "Ballyhoo." 
3.  Proper names are good in this field. The heroes of antiquity, 
figures from Greek and Roman mythology, the constellations and 
stars, famous racehorses, names of British and American war 
heroes, could be used, provided they fall within the rules above. 
There are no doubt many other themes that could be suggested. 
4.  Care should be taken in all this process. An efficient and a 
successful administration manifests itself equally in small as in 
great matters. 
 
The Americans demonstrated a like sensitivity when they codenamed 
the crowning operations of the Pacific War, the invasion of Japan, 
CORONET and  OLYMPIC . But it remained for Churchillian eloquence to find 
the great codename of the war for the greatest operation of the war. The 
name evoked a sense of majesty and patriarchal vengeance and 
irresistible power for the supreme Allied effort to enter the continent of 
Europe and crush forever the wicked Nazi conspiracy. The master 
wordsmith himself consecrated that crusade with the codename 
Operation  OVERLORD . 
Before that vast offensive could be mounted, the Allies had to win the 
Battle of the Atlantic. In this, communications intelligence played a role 
of high importance. Indeed, in some respects the Battle of the Atlantic 
might be viewed as a duel between the Axis and the Allied cryptanalytic 
organizations. And while Donitz' B-Dienst had its successes, the Allied 
communications intelligence 
agencies enjoyed the advantage of access to the extremely heavy 
traffic of the U-boat fleet. 
In part, this stemmed from Donitz' insistence on maintaining tactical 
control of his submarines so as to concentrate them in wolf packs on the 
richest prizes. He was aware of the danger in all the talk, but, he 
contended, "The signals from the U-boats contained the information 
upon which was based the planning and control of those combined 
attacks which alone held the promise of really great success against the 
concentrated shipping of any enemy convoy." His encouragement of 
communication led to an almost complete relaxation of radio discipline. 
U-boats went on the air to report a toothache on board or to congratulate 
a friend at headquarters on a birthday. U-boat command became "the 
most gabby military organization in all the history of war." 
Thanks to Commander Laurance F. Safford, head of OP-20-G and 
father of the Navy's communications-intelligence organization, the United 
States had, upon its entrance into the war, an Atlantic arc of high-
frequency direction-finders to exploit the U-boat garrulity. Stations 
reported their bearings to their net control center in Maryland, whence 
they were flashed to the naval communications-intelligence organization 
at 3801 Nebraska Avenue, North West, in Washington. Commander 
Knight McMahon and his staff combined them into fixes and flashed 
these to the Atlantic Section of the Navy Commander in Chief's Combat 
Intelligence Division. From here they sped to antisubmarine forces. 
How fast this net—called "huffduff' from the HF/DF abbreviation of 
"high-frequency direction-finding"—could work was shown by the episode 
of June 30, 1942. That morning, U-158 went on the air to report to 
Donitz that he had nothing to report. Huffduff stations at Bermuda , 
Hartland Point, Kingston, and Georgetown heard him. McMahon plotted 
his positiori as latitude 33 degrees north, longitude 67 degrees 30 
minutes west. This information raced down through channels until it 
reached Lieutenant Richard E. Schreder, U.S.N., flying an antisubmarine 
patrol out of Bermuda. Ten miles from the spotted location he found U-
158 loafing on the surface, its crew sunbathing. One of Schreder's depth 
charges landed on the submarine's superstructure just as it was trying 
to dive. It went down all right, but it never came up. 
In another case, huffduff hounded a U-boat to death. The net first 
heard a transmission of U-66 on April 19, 1944, and followed her 
successive messages in her attempts to rendezvous with a supply 
submarine. Allied ships, told where to go by huffduff, repeatedly 
frustrated these efforts, and on May 5 her commander wirelessed home: 
"Refueling impossible under constant stalking. Mid-Atlantic worse than 
Bay of Biscay." Her "spurt" transmission—made by tape-recording the 
message and then radioing the tape at high speed—lasted less than 15 
seconds, but no fewer than 26 huffduff stations got bearings on it, 
probably as a result of improved equipment that scanned the horizon 20 
times a second and zeroed in accurately and semiautomatically on any 
emission. Three hours later, an American plane spotted the U-boat; an 
hour after that an American ship began to attack it, and within 25 
minutes the submarine had gone down. 
In addition to huffduff, an intercept network eavesdropped on the text 
of the German messages. The Navy monitors could often tell one U-boat 
from another by the sending characteristics of their radio operators, and 
sometimes could ascertain the number of U-boats in a wolf pack. They 
grew so familiar with the submarine signals that they sometimes knew 
simply from external characteristics that a given message was a convoy 
contact report or a signal that attack had begun. 
Help was obtained from the most exciting code theft of World War II. It 
took place on the high seas with lightninglike speed under conditions of 
great peril . 
Early in 1944, Captain Daniel V. Gallery , U.S.N., commanding the 
antisubmarine Task Group 22.3, conceived a daring plan for boarding a 
U-boat and capturing it if, as sometimes happened, it surfaced after 
depth-charge damage to allow its crew to escape. Even though the plan 
as a whole might fail, he might pirate the submarine's cryptographic 
equipment, which alone would make such a venture worthwhile. So he 
trained a team of volunteers in dismantling booby traps, closing sea 
cocks, and handling a U-boat. 
On May 31, 1944, be began tracking  U-505, which huffduff had 
discovered was apparently heading for its home port at Brest . At 11 a.m. 
Sunday, June 4, a clear day with a light breeze , he made sound contact 
with the U-boat about 150 miles west of Cape Blanco, French West 
Africa. Its captain was at lunch when a salvo of depth 
charges slammed the peacefully gliding vessel, holing the outer hull 
and convincing him that his ship was mortally stricken. He blew his 
tanks and surfaced, and as his crew boiled out of hatches and the 
conning tower and leaped into the sea, U.S.S. Pillsbury was lowering a 
whaleboat carrying the boarding party. 
A few moments later, it reached the abandoned sub, rocking gently in 
the long Atlantic swells. Lieutenant (j.g.) Albert L. David, leading the 
boarding party, and petty officers Arthur K. Knispel and Stanley E. 
Wdowiak slipped through the hatch , raced forward to the radio room, 
smashed open a couple of lockers, and grabbed the cryptographic 
equipment—the current codebook with superenci-pherments, the 
Enigma machine and its list of keys, and hundreds of messages with 
parallel plaintexts and cipher-texts. The Germans had apparently never 
considered the possibility of a boarding and so had not bothered to 
jettison the material. The three Americans hastily passed the items up on 
deck so that the team would have something to show for its efforts even if 
it lost the sub. 
But within fifteen minutes, the team had disconnected demolition 
charges and shut off an eight-inch stream of water, and U-505 had 
become the first enemy warship captured by a U.S. Navy boarding party 
since the War of 1812 . 
The Allies now read U-boat operational traffic. For they had, more 
than a year before the theft, succeeded in solving the difficult U-boat 
systems and—in one of the finest cryptanalytic achievements of the 
war—managed to read the intercepts on a current basis. For this, the 
cryptanalysts needed the help of a mass of machinery that filled two 
buildings. 
What all this did to the submarines was graphically described by the 
German naval officer Harald Busch: "In the latter half of 1944 no U-boat 
commander would incur the ordeal of refueling if he could possibly avoid 
it. ... on a suspiciously large number of occasions, enemy aircraft had 
made their appearance at the very moment when the pipeline was 
stretched between the two boats and neither was able to dive, with the 
result that many U-boats had been destroyed in the act of refueling. . . . 
Evidently U-boat commanders were right in their suspicions: the enemy 
could and did decipher the signals transmitted by Admiral Donitz' 
headquarters in Berlin." 
in the eleven months remaining before the end of the European war, 
the Allies, greatly aided by the information that told them where to send 
their now powerful air and naval forces, sank nearly 300 U-boats—
almost one a day —and greatly reduced their shipping losses. "Battles 
might be won or lost," Churchill wrote, "enterprises might succeed or 
miscarry, territories might be gained or quitted, but dominating all our 
power to carry on the war, or even keep ourselves alive, lay our mastery 
of the ocean routes and the free approach and entry to our ports." These 
the Allies mastered. "Reduced to the simplest terms," wrote one author in 
a study of the Battle of the Atlantic, "the Allies won the U-boat war and 
Germany lost it because Donitz talked too much." 
Final victory over the Nazi evil could come only by driving a military 
stake through its heart, and in this mission communications intelligence 
played an important role. The march actually began in North Africa in 
1942 under the pressure for a "Second Front Now." Communications-
intelligence units were there—though not exactly in the role assigned 
them. Radio-intelligence companies of the American Army charged 
ashore as assault troops! They soon resumed their proper duties, 
however, and, equipped with intercept receivers and direction-finders, 
began to eavesdrop on the Axis messages. During the Tunisia campaign, 
the 128th, 117th, 122nd, 123rd, and 849th Signal Companies (Radio 
Intelligence) tracked the Germans all over North Africa and, by 
monitoring American communications, plugged leaks in Allied radio 
security. The 128th first discovered that the Germans were withdrawing 
from the Kasserine Pass, which they had taken a few days earlier in 
America's first blooding in Europe. Later the 128th gave advance warning 
of several enemy attacks. In Italy, the VI Corps intelligence officer said 
that his radio intelligence platoon had done "outstanding" work during 
the march on Rome and had supplied information second in value only 
to battle reconnaissance. Thus, even though the manning and equipping 
of radio intelligence companies did not get under way until relatively late 
in the war, officers in the field soon declared their product to be "of 
material value ... at times vital" and praised the units as among the 
"most constantly profitable sources" of intelligence on German plans and 
movements. 
Strategic communications intelligence about German in- 
tentions in the European war mainly came, however, from Japanese 
sources. This should not be surprising. The Wehrmacht had the 
advantage of interior communications throughout occupied Europe and 
so could use wire networks, which offer very little opportunity for 
interception. But the Japanese diplomats in Berlin, Rome, Madrid, 
Lisbon, Sofia, Budapest, and Moscow had no way of getting messages 
back to Tokyo but by radio. These the Allies intercepted. 
The messages of the Japanese military attaches, whose code the 
United States had broken, yielded quantities of information. This source 
was lost to the Allies in 1943 in an ironic development that demonstrates 
the superiority of cryptanalysis over theft as a secret source of 
information. The Office of Strategic Services, America's new spy outfit, in 
a laudable attempt at espionage, penetrated the offices of the Japanese 
embassy in Portugal. They did not disclose their plans to the Army, 
whose Signal Security Agency (formerly the Signal Intelligence Service) 
had broken the code; nor did the Army warn the O.S.S. against doing 
anything that would jeopardize its cryptanalyses. The upshot was that 
the Japanese discovered traces of the search, decided that their military 
ATTACHÉ code might have been compromised, and changed it. The Allies, 
who had been comfortably reading the messages without benefit of 
espionage, still had not broken into the new code by the fall of 1944. 
Thus the attempt to gain information by cloak-and-dagger methods 
deprived the United States of information that it had been obtaining by 
the traceless means of communications intelligence. 
Bulky cipher machines such as the Japanese diplomats used could 
not be shipped or smuggled into blockaded Europe very easily, and so 
PURPLE remained in service throughout the war. Quite probably the 
Japanese considered the system secure. But even before Pearl Harbor 
American cryptanalysts were reading Japanese PURPLE messages from 
Berlin, and they preyed upon them even more avidly after the United 
States entered the war. Thus William F. Friedman's solution of PURPLE 
reverberated throughout the war, leading to major effects and making it 
one of the world's great cryptanalyses not only in technique but in 
importance as well. 
The Germans granted the Japanese ambassador, Baron Hiroshi 
Oshima, the intimacies of an ally, and, as a former 
military attache, he took considerable interest in the military sphere. 
Toward the end of October, 1943, when it became evident that the Allies 
would invade Europe and the Wehrmacht had begun to stiffen its 
defenses, Oshima toured the Westwall and the Siegfried Line. He 
reported on these preparations in great detail in a long radiogram of 
between 1,000 and 2,000 words. 
As a powerful German station pumped it into the ether for the 5,000-
mile leap to Tokyo, a new American intercept post at Asmara, in the 
former Italian colony of Eritrea bordering the Red Sea, picked it up. Back 
the cryptogram went to the Signal Security Agency. It proved to be in 
PURPLE, which the American cryptanalysts read with relative ease. The 
solution went to General Dwight D. Eisenhower's headquarters, where its 
intelligence helped shape basic strategy for the conquest of Germany. 
 
14. Censors,  Scramblers, and Spies 
 
CIPHER is the language of spies—and usually they must talk in whispers. 
A spy's success, his very existence, depends on his not being seen or 
heard. Sending messages in obviously cryptographic form would alert 
counterespionage to him as effectively as wearing a cloak and dagger. Yet 
he must transmit, else he is useless. So he eschews the overt methods of 
secret communications for the covert. He resorts to open codes, hollow 
heels, invisible inks, microscopically small missives—the stegano-graphic 
methods that conceal the very fact that a message is being sent. He seeks 
to communicate unnoticed. 
And to block this very attempt and root out the enemy within, 
governments erect great filters at their mail and cable ports of entry to 
prevent and detect these clandestine communications. These sieves, 
which let innocent messages flow through, are the censorship 
organizations. 
Descended in a sense from the black chambers of the 1700s, they are 
creatures of war in democracies and of tyranny in dictatorships. 
Censorship first sprang up on a major scale in World War I, and the 
lessons that Britain learned then she put to good use twenty years later 
when 
S, SCRAMBLERS, AND SPIES      275 
she again filtered communications. Even before the United States 
entered the war, British censorship had caught two major German spies 
in the United States and its protectorate of Cuba. 
In December, 1940, one of the 1,200 examiners that British 
censorship had installed in the commodious Princess Hotel in Bermuda 
stopped a letter addressed to Berlin from New York. He suspected it 
because it described a list of Allied shipping and used several 
expressions— such as "cannon" for "guns" in describing the vessels' 
armament—that suggested the writer might be German and a possible 
Nazi agent. The letter was signed "Joe K." A watch set up for more letters 
with his handwriting soon picked out quite a few more, mostly to Spain 
and Portugal. Their language seemed slightly forced, and a team began 
studying the letters to see whether this indicated an open code and, if so, 
what the real meaning was. 
One member of the team was a persistent young woman named 
Nadya Gardner , who became convinced that the letters contained 
invisible writing. The usual strip tests with chemicals that bring out the 
ordinary secret inks gave negative results, but Miss Gardner persisted. 
Finally the chemists, under Dr. Enrique Dent, applied the iodine-vapor 
test invented back in World War I—and to their surprise secret writing 
did appear on the back of the typed sheets. The letter of April 15, 1941, 
addressed to Mr. Manuel Alonso, Apartado 718, Madrid, carried on the 
back of its two pages a list of ships then docked at New York: "On April 
14 was at pier 97 (Manhattan) the Norwegian M. S. Tain  Shan —6601 
tons—gray superstr # at pier 90 was a Dutch freighter. ..." A letter of six 
days later, addressed to a Miss Isabel Machado Santos in Lisbon, 
reported in invisible ink that "British have about 70,000 men on Iceland  
# The S.S.  Ville de Liege was sunk about April 14—many thanks # Types 
of airplanes flown to England (continued from letter 69) —3. Boeing B-
17c (model 299x) twenty were released by the U.S. Army to Britain on 
Nov. 20. . . ." These little billets-doux were written in a solution of 
pyramidon, a powder often used as a headache cure and readily 
obtainable at most pharmacies. 
But there was still no clue as to the sender. The letters bore no return 
address, and it was rather unlikely that "Joe K" was the spy's real first 
name and last initial. 
Z7b       THE COUEBKEAKtKS 
Finally, British censorship picked out another Joe K letter that 
reported that " Phil " had been fatally injured in a New York traffic 
accident on March 18 and had died at St. Vincent's Hospital. F.B.I, 
agents found that the man in the accident was known as Julio Lopez  
Lido, and that witnesses had seen that a man with Lido had grabbed his 
briefcase after the accident and hurried away. Eventually, the agents 
learned that Lido's true name was Ulrich von der Osten and that the 
writer of the Joe K letters was Kurt Frederick Ludwig . Ludwig, born in 
Ohio but raised in Germany, had come to the United States in March of 
1940 to organize a spy ring, which he had done with moderate success. 
When captured, he had several bottles of pyramidon in his 
possession. The odd tone of the open text of his letters was accounted for 
by its double meanings. "Your order 5 is rather large—and I with my 
limited facilities and funds shall never be able to fill such an immense 
order completely," he wrote to one of his addressees—all of them, 
incidentally, cover addresses for Himmler. This message really meant 
that he would have difficulty fulfilling the instructions sent him in 
communication No. 5 because of two few agents and too little money. 
Ludwig was convicted in the U.S. District Court at Brooklyn. 
The second spy trapped by the alert Bermuda station went to his 
death. On a November day in 1941, an alert censor detected a rather 
Germanic cast to the handwriting in a Spanish-language letter from 
Havana to Lisbon and sent it over for a routine test for secret ink. His 
intuition was confirmed when a long missive appeared, listing ships 
being loaded in Havana harbor and discussing an airfield being 
constructed. The examiners were alerted to watch for similar 
handwriting. The next letter turned up a few days later. Censorship 
continued picking out these letters, which recited details of merchant 
shipping in Cuban waters and of the enlargement of the U.S. Navy's base 
at Guantanamo Bay, until the writer's real Havana address showed up in 
secret ink. Letters posted to this address were watched, and on 
September 5, 1942, after sufficient evidence had been amassed, police 
arrested "R. Castillo ," who proved to be Heinz August Luning. He had 
been sent to Havana from Germany in September, 1941, and of the 48 
letters he had sent to Europe, the Bermuda censors had intercepted all 
but five. On November 9, 
1942, he went before a firing squad at Principe Fortress, the first man 
in Cuba to be executed as a spy. 
Soon after Pearl Harbor, the United States built up a censorship 
service that began in the borrowed office in which Byron Price went to 
work as Chief Censor and grew to an organization whose 14,462 
examiners occupied 90 buildings throughout the country, opened a 
million pieces of overseas mail a day, listened to innumerable telephone 
conversations, and scanned movies, magazines, and radio scripts. 
Millions became familiar with the "Opened by Censor" sticker and the 
scissored letter. 
To plug up as many steganographic channels of communication as 
possible, the Office of Censorship banned in advance the sending of 
whole classes of objects or kinds of messages. International chess games 
by mail were stopped. Crossword puzzles were extracted from letters, for 
the examiners did not have time to solve them to see if they concealed a 
secret message, and so were newspaper clippings, which might have 
spelled out messages by dotting successive letters with secret ink—a 
modern version of a system described more than 2,000 years earlier by 
Aeneas the Tactician. Listing of students' grades was tabooed. One letter 
containing knitting instructions was held up long enough for an 
examiner to knit a sweater to see if the given sequence of knit two and 
cast off contained a hidden message like that of Madame Defarge , who 
knitted into her "shrouds" the names of further enemies of the French 
Republic, "whose lives the guillotine then surely swallowed up." A stamp 
bank was maintained at each censorship station; examiners removed 
loose stamps, which might spell out a code message, and replaced them 
with others of equal value, but of different number and denomination. 
Blank paper, often sent from the United States to relatives in paper-short 
countries, was similarly replaced from a paper bank to obviate secret-ink 
transmissions. Childish scrawls, sent from proud parents to proud 
grandparents, were removed because of the possibility of their covering a 
map. Even lovers' X's, meant as kisses, were heartlessly deleted if 
censors thought they might be a code. 
Censorship cable regulations prohibited sending any text that was 
unclear to the censor, including numbers unrelated to the text or a 
personal note in a business communication, and that was not in English, 
French, Spanish, 
or Portuguese plain language. To kill any possible sub rosa message, 
censors sometimes paraphrased messages. This practice gave rise to 
Censorship's classic tale, which dates back to World War I. Onto the 
desk of a censor was placed the cablegram Father is dead. The censor 
considered it briefly, changed it to Father is deceased, and forwarded it. 
Soon thereafter the reply appeared on his desk: Is Father dead or 
deceased? 
Cables ordering flowers—"Deliver three white orchids to my wife 
Saturday"—offered so blatant an invitation to clandestine communication 
that the censors forbade naming the kind of flower and the date of 
delivery, leaving both up to the individual florist. Later in the war, all 
international flower messages were prohibited by the United States' and 
Great Britain because of the danger of their masking signals. Only those 
between the U.S. and her territories and between the U.S., Canada, and 
Mexico were permitted. The censorship permitted only nine of the most 
widely used commercial codes, and every coded message had to include 
an indicating abbreviation in its preamble. A firm could not use its 
private code without a special license from the director of censorship, 
who required that fifteen copies of the codebook be furnished for use by 
the censors.* 
Precautions were taken with the mass media, too. Newspapers were 
warned to be careful in taking want ads. Prevention was directed mainly 
at commercial radio, which could instantaneously deliver open-code 
secret 
*At the start of the war in September, 1939, the Allies prohibited the 
use of any codes at all. But pressure of business houses and realization 
that commercially coded messages were only a step up from plaintext 
forced them to relent, and at the end of December they permitted the use 
of  Bentley 's Complete Phrase Code, Bentley's Second Phrase Code, the 
ABC Code (6th edition), and  Peterson 's Code (3rd edition). In April, 1940, 
they admitted five more codes: Acme Code and Supplement,  Lombard  
General Code, Lombard Shipping Code and Appendix , New Standard Half 
Word Code, and New Standard Three Letter Code. These were the nine 
later allowed by the United States and most of the Latin American 
nations. Under pressure from the Allies, Argentina, which had not 
severed diplomatic relations with the Axis, halted all code 
communications—but the first code message stopped was one from the 
Vatican! During the war, even neutrals such as Spain and Sweden 
demanded copies of the codes used and prohibited the use of (secret) 
cipher. Only Switzerland placed no restrictions on either code or cipher 
communication. 
messages to listening submarines or enemy agents with the greatest 
of ease. Such possibilities had been driven home forcefully to the 
broadcasting industry a year before Pearl Harbor in a test conducted by a 
military intelligence officer. By having an announcer mention England's 
Queen Elizabeth, the officer wove into an interview with former 
heavyweight champion Max Baer the hidden message: S-112: Queen 
Elizabeth sails tonight with hundreds of airplanes for Halifax. What was 
disturbing was that neither the announcer, the station manager, Baer, 
nor any of the thousands of listeners on the nationwide hook-up except 
those who had been initiated into the secret were aware that the message 
had been broadcast. With this in mind, the Office of Censorship ruled 
that telephone or telegraph requests for phonograph records were not to 
be honored, and that mail requests must be held for an irregular, 
unspecified time before playing. This would defeat any attempts to have 
"Jersey Bounce" tell a waiting U-boat that Convoy sails today. The same 
situation applied to the personal ads, such as for lost dogs, that local 
stations broadcast. Halted completely were man-in-the-street interviews 
and Santa Claus lists of toys that children wanted. 
Preventive censorship like this was only half the job, however. It could 
not be expected that spies would limit themselves to such easily 
confounded methods of communication. The other half of the job was the 
detection of the other methods that they might use. To sharpen 
Censorship's spy-catching tools by coordinating and assisting the field 
stations that spotted the hidden messages and by improving liaison with 
counterespionage agencies like the F.B.I., Price in May of 1943 
established the Technical Operations Division at headquarters, 
appointing Lieutenant Colonel Harold R. Shaw as its chief and an 
assistant director in the Office of Censorship. 
T.O.D. was quartered in the Federal Trade Commission 
|; Building, the three-sided structure that housed the Office 
of Censorship at Pennsylvania and Constitution avenues 
in Washington.   Shaw  administered  it  from  Room  509 
with three assistants and a secretarial staff. Two technical 
sections operated under maximum security in a windowless, 
| guarded area on the seventh, or top, floor. The laboratory 
was headed by Dr. Elwood C. Pierce , a biochemist at the 
University of Indiana who had joined Censorship at the 
start of the war. He and his assistant, Dr. Willard Breon 
of the University of Maryland chemistry faculty, had prepared a 
manual on detection of secret inks, trained key personnel of the 
censorship field stations in laboratory operation, and handled some of 
the more active and difficult cases themselves. From Hawaii Shaw 
imported his trusted cryptanalytic expert to form a unit "capable," he 
said, "not only of cracking codes and ciphers but also of building the 
intricate dossiers of personal history, contacts, handwriting peculiarities, 
and correspondence habits of each actual and suspected espionage 
agent." The man who could do it was Armen Abdian, a former New 
Englander who had come to Hawaii in the prewar Army, had taught a 
cram course for prospective West Pointers, and had gone into business in 
Honolulu. 
The primary detection of clandestine communications took place in 
the censorship field stations. Largest of all was New York's, filling a huge 
building on Lower Eighth Avenue. About 4,500 postal examiners scanned 
the snowdrifts of mail that piled onto their desks each day. They excised 
all matter that might have injured the Allied war effort, and they looked 
closely for traces of hidden messages. Censorship had catalogued the 
occupations and hobbies of its examiners. A balance sheet would be 
given to an accountant to see whether it made financial sense; an 
amateur horticulturist could tell whether a discussion of tulip beds rang  
true. Once an examiner in New York was perturbed by a letter from 
Germany to a prisoner of war in the United States, saying that Gertrude  
was developing into a swimming champion and listing the times of her 
victories. He consulted an amateur swimmer in the office, who reported 
that the speeds were impossible. Further investigation revealed that the 
times actually indicated the speed of a new- fighter plane, given by a war 
worker who could not resist bragging. The factory was later bombed. 
Censors in a political section looked for clues to hoards of vital material 
that might be bought by the Allies to preclude the Axis from getting it. An 
economic section extracted remarks about shortages and living 
conditions to help build up pictures of national economies . Letters in 
uncommon languages went to a language identification section, which 
obtained translators for such esoteric tongues as Ladino, a mixture of 
Hebrew and 15th-century Spanish spoken only by the 30,000 Sephardic 
Jews in colonies in Spain, the Balkans, and Latin America. 
Floor examiners passed all messages with peculiar wording, odd-
looking marks, or other suspected indications to the security division, 
which had two sections to examine steganograms concealed in the two 
basic ways—linguistically and technologically. These were the code and 
cipher section for the linguistic steganograms and the laboratory section 
for the technological. Both were linked to T.O.D. by a security assistant 
who implemented T.O.D.'s instructions and passed the more recalcitrant 
problems back to Washington. The 70 examiners in the New York code 
and cipher section occupied about half the 14th floor, with some of the 
more expert people constituted as a specialist group. About 30 
technicians tested for secret inks in the laboratory next door. 
Linguistically concealed messages fall into two general categories, the 
semagram and the open code. There are three kinds of open code: the 
jargon code, the null cipher, and geometrical systems like the Cardano 
grille. In the jargon code, an apparently innocuous word stands for the 
real term in a text contrived to seem as bland and as innocent as 
possible. Jargon codes can range from the most informal sort of code to a 
full code list. They begin with mere allusions to mutually known events 
and persons —"I visited the man you had dinner with last week." They 
continue through double meanings that would be easily understood by 
the recipient, as one criminal's referring to another's arrest by saying 
"Joe went to the hospital." They culminate in a prearranged table of 
artificial meanings. Jargon has been popular since the dawn of 
cryptography. The Chinese employed it; the oldest papal code is the 
14th-century use of EGYPTIANS for Ghibellines and SONS OF ISRAEL for 
Guelphs; in the 17th century a French code consisted entirely of such 
jargon expressions as GARDEN for Rome, ROSE for the pope, PLUM TREE for 
the Cardinal de Retz, WINDOW for Monsieur the king's brother, and 
STAIRCASE  for the  Marquis de Coeuvres. It is clear that skillful application 
of jargon's literary veneer requires no little finesse! 
Censorship defends itself against this ruse by a feel for stilted or 
heavy-handed language and by a healthy skepticism concerning subject 
matter. The standard story about jargon comes from World War I. A 
British censor grew suspicious of the enormous orders for cigars wired 
each day—mostly from port towns—by two "Dutch business- 
men." One day Portsmouth called for 10,000 Coronas; the next day 
Plymouth and Devonport craved large quantities of stogies; then 
Newcastle succumbed overnight to the tobacco habit. It seemed as 
though all the males in the coastal population of England had suddenly 
and simultaneously developed an irresistible addiction to the weed , so 
inexhaustible was the demand for cigars. At the suggestion of the censor, 
a check was made; the two businessmen proved to be German spies, and 
their orders an open code, in which, say 5,000 Coronas for Newcastle 
meant five cruisers lying in that port. On July 30, 1915, the two— 
Haicke P. M, Janssen and Wilhelm R. Roos—were executed at the Tower 
of London by a firing squad whose triggers were really pulled by an alert 
censor. 
A second type of open code is the null cipher. Only certain letters or 
words of a null cipher's text are significant; for example, every fifth word 
or the first letter of every word, with all the other letters and words 
serving as nulls to produce the disguise. These usually sound even more 
strained than the jargon code. Even two of the better examples, sent by 
the Germans during World War I, have that "funny" sound that 
invariably accompanies them. The first, disguised as a press cable, read: 
 
PRESIDENT'S EMBARGO RULING SHOULD HAVE IMMEDIATE NOTICE. GRAVE 
SITUATION AFFECTING INTERNATIONAL LAW. STATEMENT FORESHADOWS RUIN 
OF MANY NEUTRALS. YELLOW JOURNALS UNIFYING NATIONAL EXCITEMENT 
IMMENSELY. 
 
The initial letters spell out Pershing sails from N.Y. June 1. The second 
message, apparently sent as a check on the first, beaded the same 
content on the second letters of each word: 
 
APPARENTLY NEUTRAL'S PROTEST IS THOROUGHLY 
DISCOUNTED AND IGNORED. ISMAN HARD HIT. BLOCKADE 
ISSUE AFFECTS PRETEXT FOR EMBARGO ON BYPRODUCTS, 
EJECTING SUETS AND VEGETABLE OILS. 
 
Whoever the sender was, his ingenuity was expanded in vain, since 
Pershing actually sailed May 28. 
Most null ciphers in World War II were used not by 
spies, but by otherwise loyal Americans who could not resist trying to 
"beat the censor." Servicemen in particular attempted to sneak 
information about their whereabouts to families who otherwise would 
quite literally not know where in the world their soldier boy was—even 
though such attempts endangered the serviceman's own life. 
One such system, though elementary, brought deserved bewilderment 
instead of clarification to its intended recipients. A young GI, following a 
prearranged system with his parents, tried to tell them he was in Tunis 
by using first T, then u, then N, i, and s as his father's middle initial in 
successive letters home. Unfortunately, he forgot to date them and they 
arrived out of order. The frantic parents wrote that they had looked and 
looked through their atlas but couldn't find Nutsi anywhere! Attempts of 
this sort grew so frequent by 1943 that the Navy had to warn its sailors 
that these "family codes," which were usually solved quite easily, could 
lead to severe penalties for the users. 
The third kind of open code is the geometrical. A Cardano grille places 
the message-bearing words in fixed positions on a page. The significant 
words can be placed at intersections of the lines of a geometrical diagram  
of specified dimensions. In the 1600s, Sir John Trevanion, a Cavalier 
awaiting trial and almost certain execution by Cromwell's forces, noted 
the third letter after each punctuation mark in a letter that his jailers 
had scrutinized before giving him arid learned that Panel at east end of 
chapel slides. He disappeared during vespers. And in World War II, 
captured U-boat officers spelled out secret messages in their letters home 
by breaking the flow of script after each significant letter. An alert censor 
noticed that the minute gaps did not occur in natural places, as after 
syllables. The hidden messages described Allied anti-submarine tactics 
and technical U-boat faults. Some outlined escape plans— which were, of 
course, foiled. 
The second category of linguistically concealed messages is the 
semagram (from the Greek "sema," for "sign"). A semagram is a 
steganogram in which the ciphertext substitutes consist of anything but 
letters or numbers. The astragal of Aeneas the Tactician, in which yarn 
passing through holes representing letters carried the secret message, is 
the oldest known semagram. A box of Mah-Jongg tiles might carry a 
secret message. So might a drawing in 
which two kinds of objects represented the dots and dashes of Morse 
Code to spell out a message. The New York censorship station once 
shifted the hands and altered the positions of the individual timepieces 
in a shipment of watches lest a message be concealed in it. 
The examination of the linguistically concealed messages —or, more 
correctly, those suspected to be such—was largely a frustrating 
experience. Often the examiner could not tell whether or not a message 
was hidden beneath the awkward or illiterate or misspelled writing. And 
even if he felt certain, solution often eluded him. He usually had only one 
message to work on, and no probable words. Early in the war, censorship 
practice even forbade working on a suspected cryptogram more than half 
an hour, on the theory that if the cryptanalyst hadn't gotten it by then, 
he'd never get it. These unsolved messages posed a difficult problem to 
the censors. Presumably they were carrying contraband information and 
so should be banned. But, in the absence of solution, no proof of this 
existed, and so the letter could not be mutilated. Sometimes this was 
done anyway, to destroy the suspected code. 
Technological steganography early in the war consisted almost 
exclusively of invisible inks. This is truly an ancient device. Pliny the 
Elder, in his Natural History, written in the first century A.D., told how 
the "milk" of the tithy-mallus plant could be used as a secret ink. Ovid 
referred to secret ink in his Art of Love. A Greek military scientist, Philo  
of Byzantium, described the use of a kind of ink made from gall nuts 
(gallotannic acid), which could be made visible by a solution of what is 
now called copper sulfate. Qalqashandi described several kinds of 
invisible ink in his Subh al-a' sha. Alberti mentions them. The 
Renaissance employed them in diplomatic correspondence. About 1530 a 
book was printed with panels in invisible ink; if these pages were dipped 
in water, the message would appear; this could be repeated three or four 
times. 
The common inks are of two kinds: organic fluids and sympathetic 
chemicals. The former, such as urine, milk, vinegar, and fruit juices, can 
be charred into visibility by gentle heating. Despite their antiquity and 
their minimal protection, they are so convenient that they were used 
even during World War II. Count Wilhelm Albrecht von Rautter, a 
naturalized American who was spying on his 
adoptive country for his native Germany, ran out of his good secret 
ink and had to use urine. 
Sympathetic inks are solutions of chemicals that are colorless when 
dry but that react to form a visible compound when treated with another 
chemical, called the reagent. For example, when a spy writes in iron 
sulfate, nothing will be visible until it is painted over with a solution of 
potassium cyanate, when the two chemicals will combine to form ferric 
ferrocyanide, or Prussian blue, a particularly lovely hue. The colorless 
writing of lead sub- acetate will turn into a visible brown compound when 
moistened with sodium sulfhydrate. Copper sulfate can be developed 
with ammonia fumes, and it may have been this chemical that was used 
for the secret writing on the handkerchief of George Dasch, leader of the 
eight Nazi spies who landed by submarine on Long Island in 1942 to 
blow up American defense plants , railroad bridges, and canal locks. The 
red letters that appeared as if by magic when the pungent ammonia 
reached it spelled out the names and addresses of a mail drop in Lisbon 
and of two reliable sources for help in the United States. Each of the 
eight saboteurs had also been given a watertight tube containing four or 
five matchsticks tipped with a grayish substance that served as a ready-
made pen-and-secret-ink. The trick in concocting a good secret ink is to 
find a substance that will react with the fewest possible chemicals— only 
one, if possible, thus resulting in what is called a highly "specific" ink. 
To test for secret inks, censorship stations "striped" letters. The 
laboratory assistant drew several brushes, all wired together in a holder  
and each dipped in a different developer, diagonally across the suspected 
documents. The developers were wide-spectrum, picking up even such 
substances as body oils, so that fingerprints and sweat drops often 
showed up. On the other hand, they missed some specific inks. A 
bleaching bath removed the stripes. Letters were also checked by 
infrared and ultraviolet light. Writing in starch, invisible in daylight or 
under electric light, will fluoresce under ultraviolet. Infrared can 
differentiate colors indistinguishable in ordinary light and so can pick 
up, for example, green writing on a green postage stamp. The censorship 
field stations tested all suspicious letters and a percentage of ordinary 
mail picked at random, and sometimes all letters to and from a certain 
286      THB CUJJJiBKliAKERS 
city for a week to see if anything suspicious turned up. During the 
war, about 4,600 suspicious letters were passed along to the F.B.I, and 
other investigative agencies; of these 400 proved to be of some 
importance. 
Problems that would not yield to the crude approach of the field 
stations went back to the T.O.D. laboratory. Here, amid Bunsen burners 
and retorts, Pierce and Breon, aided by an expert photographer and 
laboratory technicians, cooked up reagents that would reincarnate the 
phantom writing. Better equipped and more deeply versed in the nuances 
of sympathetic inks than the mass-production workers of the field 
stations, they had received a great stimulus from contact with one of the 
great secret-ink experts of the world, England's Dr. Stanley W. Collins , 
who had conducted this battle of the test tubes in two World Wars; he 
spoke at the Miami Counter-Espionage Conference in August, 1943. 
T.O.D. soon learned that Nazi spies were taking countermeasures to 
frustrate the iodine-vapor test and the general reagent. 
One was to split a piece of paper, write a secret-ink message on the 
inner surface, then rejoin the halves. With the ink on the inside, no 
reagent applied to the outside could develop it! The technique came to 
light when one German spy used too much ink and the excess soaked 
through. Sanborn Brown, an M.I.T. physicist, got two inmates of a local 
jail to explain how two sheets of parchment could be used to do the 
splitting. They had been caught misapplying the talent to one- and ten-
dollar bills, pasting one half of the tens to one half of the ones and 
passing them with the ten-dollar side up. The method is more an art 
than a science, for if the sudden tear is not done just right, the paper will 
shred. To read the message, the paper must be resplit, but it comes 
apart much more easily the second time. 
Another antidetection measure was transfer . German agents would 
write their message in invisible ink on one sheet of paper, then press this 
tightly against another sheet. Moisture in the air would carry some of the 
ink to the second sheet without the telltale differential wetting of the fiber  
papers on which the iodine test relied. This compelled T.O.D. to find the 
specific reagent required. 
Perhaps the most interesting development of the secret-ink war was 
the German instrument discovered by Shaw, Pierce, and others in 1945 
and dubbed the "Wurlitzer 
Organ" because of its resemblance to that musical instrument. They 
found a burned-out shell of one "organ" in the bombed remnants of the 
Munich censorship station, and an undamaged one in the censorship 
station on an upper floor of the Hamburg post office. It examined 
suspected letters on an assembly-line basis by ingeniously exploiting 
some principles of physics to make the invisible ink glow. It first exposed 
the paper to ultraviolet light. This pumped energy into chemicals of the 
ink, boosting their electrons out of their normal orbits into higher ones. 
The chemical was then in a metastable state. The heat from a source of 
infrared then nudged the electrons from their higher orbits back into 
their regular ones. As they did so, the substance would give up, in the 
form of visible light, the energy that it had absorbed from the ultraviolet. 
Since this phenomenon will occur for nearly all substances, even 
common salt , though some will "naturally shine more brightly than 
others, the Germans had a system that would develop a good many inks. 
The chief difficulty with secret inks was their inability to handle the 
great volume of information that spies had to transmit in a modern war. 
One way of channeling large amounts was to dot the meaningful letters 
in a newspaper with a solution of anthracene in alcohol . This was 
invisible under normal circumstances but glowed when exposed to 
ultraviolet light. But with newspapers being carried as third-class mail,' 
this was hardly the fastest method of getting information to where it was 
going. 
The Germans then came up with what F.B.I. Director J. Edgar Hoover 
called "the enemy's masterpiece of espionage." This was the microdot, a 
photograph the size of a printed period that reproduced with perfect 
clarity a standard-sized typewritten letter. Though microphotographs (of 
a lesser reduction) had carried messages to beleaguered Paris as far back 
as 1870, a tip to the F.B.I, in January of 1940 by a double agent, "Watch 
out for the dots— lots and lots of little dots," threw the bureau into a near 
panic. Agents feverishly looked everywhere for some evidence of them, 
but it was not until August of 1941 that a laboratory technician saw a 
sudden tiny gleam on the surface of an envelope carried by a suspected 
German agent-—and carefully pried off the first of the microdots, which 
had been masquerading as a typewritten period. 
At first the microdot process involved two steps: A first photograph of 
an espionage message resulted in an image the size of a postage stamp; 
the second, made through a reversed microscope, brought it down to less 
than 0.05 inches in diameter. This negative was developed. Then the spy 
pressed a hypodermic needle, whose point had been clipped off and its 
round edge sharpened, into the emulsion like a cookie cutter and lifted 
out the microdot. Finally the agent inserted it into a cover-text over a 
period and cemented it there with collodion. Later, one Professor Zapp 
simplified the process so that most of these operations could be 
performed mechanically in a cabinet the size of a dispatch case. The 
microdots, or " pats ," as T.O.D. called them, were photographically fixed 
but were not developed; consequently, the image on them remained 
latent and the film itself clear. In this less obtrusive form they were 
pasted onto the gummed surface of envelopes, whose shininess 
camouflaged their own. The pats could show such fine detail because the 
aniline dye used as an emulsion would resolve images at the molecular 
level, whereas the silver compounds ordinarily used in photography 
resolve only down to the granular level. 
The microdots solved the problem of quantity flow of information for 
the Nazis. Professor Zapp's cabinets were shipped to agents in South 
America, and soon a flood of material was being sent to Germany 
disguised as hundreds of periods in telegraph blanks, love letters, 
business communications, family missives, or sometimes as a strip of the 
tiny film hidden under a stamp. The very first discovered, and the most 
frightening, was one in which a spy was asked to discover "Where are 
being made tests with uranium?" at a time when the United States was 
fighting to keep secret its development of the atom bomb. The "Mexican 
microdot ring," which operated from a suburb of Mexico City, 
microphotographed trade and technical publications that were barred 
from international channels—a favorite was Iron Age, with statistics on 
American steel production—and sent them to cover addresses in Europe 
on a wholesale basis, with as many as twenty pats in a single letter. 
Technical drawings also went by microdot. Other microdots talked of 
blowing up seized Axis ships in southern harbors, the deficient condition 
of one of the Panama Canal locks, and so on. Censorship discovered 
many of these, now that it knew what 
to look for, send this enabled the F.B.I.'s wartime Latin American 
branch to break up one Axis spy ring after another. 
 
Telephoning is an exceedingly convenient way to communicate. How 
delightfully simple to pick up a phone, talk with the other party, and get 
everything settled in one conversation! Much easier than sending written 
messages back and forth. But the telephone is notoriously insecure—and 
its offspring, the radiotelephone, even more so. A single wiretap grants 
access to a telephone conversation, and only a radio set is needed to 
overhear radiotelephone talk. And the Axis did not hesitate to grasp 
these opportunities at the highest diplomatic levels. 
The most obvious protective measure against eavesdropping is to 
make up codes for conversation, and this has of course been done at one 
time or another by almost anyone who has spoken over the telephone. 
The codes range from mere oblique references and the most impromptu 
cant to elaborately prepared lists of jargon. Less frequently, a message 
might be enciphered in a prearranged system and the ciphertext read off 
letter by letter, as the Manhattan District did with a checkerboard. Or 
the speakers may resort to a foreign language. 
The United States raised the latter device to the level of a full-scale 
system in both World Wars by making use of a resource that virtually no 
other combatant had: pools of tongues so recondite that almost no one 
else in the world understood them. These were the American Indian 
languages, which are isolated both geographically and linguistically. In 
1918, eight Choctaws of Company D, 141st Infantry, transmitted orders 
by field telephone; this was the idea of Captain E. W. Horner , who named 
Solomon Lewis as the chief of the detail. Other Indian tongues were also 
used. During preparations for World War II, the Signal Corps tested 
Comanches and Indians from Michigan and Wisconsin in war games, but 
most of the codetalkers in the combat itself were Navaho. One reason 
probably was that the tribe was large enough (more than 50,000 persons) 
to furnish a goodly number of speakers; another, that reportedly only 28 
non-Navahos—mainly anthropologists and missionaries—could speak 
the language, and none of these were German or Japanese; a third 
reason was the extreme difficulty of the tongue and 
the near impossibility—even if someone did learn it—of counterfeiting 
its sounds. 
"Sounds [in Navaho] must be reproduced with pedantic neatness . . . 
almost as if a robot were talking," wrote anthropologist Clyde Kluckhohn. 
"The talk of those who have learned Navaho as adults always has a 
flabby quality to the Navaho ear. They neglect a .slight hesitation a 
fraction of a second before uttering the stem of the word." A hint of its 
complexity may be seen in some of its verb forms, on which it insists. 
The stems of many Navaho verbs differ with the object acted upon. Thus 
one stem must be used with long objects (pencils, sticks), another with 
slender flexible objects (snakes, thongs), and still others with granular 
masses (sugar, salt), things bundled up (hay, bundles of clothing), fabrics 
(paper, blankets), viscous objects (mud, feces), bulky round objects, 
container- and- contents, animate objects, and so forth. An entirely 
different verb form concerns itself with the manner of knowing an event. 
For example, a Navaho must use one form if he himself is aware of the 
actual start of rain, another if he believes that rain was falling for some 
time in his locality before he noticed it, and so on. "Because so much is 
expressed and implied by the few syllables that make up a single verb 
form, the Navaho verb is like a tiny imagist poem." Thus "na'fldil" means 
"You are accustomed to eat plural separable objects one at a time." 
A cryptosystem like that boasts considerable security, and it is not 
surprising that the dark-skinned, black-haired Navaho became a familiar 
sight in Marine regimental, divisional, or corps command posts, 
translating a message into a conglomeration of Navaho, American slang, 
and military terminology as he huddled over a radio set in the Pacific 
combat zone. Close friends usually worked together. The number of 
Navaho codetalkers in the Marines rose from 30 at the start of the war to 
420 at the end. They relayed operational orders with a secrecy that 
helped the United States advance from the Solomons to Okinawa. 
Linguistic codetalking, jargon codes, or double meanings all use the 
human speaker as the coding machine. But this job may be delegated to 
a real machine—the scrambler. These two modes of oral secrecy, the 
human and the mechanical, correspond to the two basic forms of crypto-
systems. Human coding transmutes words, syllables, and 
sounds (as in Pig Latin)—the linguistic elements of speech —into 
secret forms and so parallels code. Both ciphers and scramblers, on the 
other hand, work upon particles of a text cut up without regard to 
linguistic functions. From this analogy, scrambler methods of modifying 
speech are called "ciphony" (from "cipher" plus "telephony"). The field of 
secret voice communication as a whole may be termed "cryptophony." 
Though it was only in World War II that scramblers came into 
widespread use, and only in that war that serious attempts began to be 
made to solve scrambled speech, devices to assure telephonic secrecy 
had been in existence almost as long as the telephone itself. The 
granddaddy of these was patented on December 20, 1881, only five years 
after Bell obtained his patent on the telephone. Its inventor, 25-year-old 
James Harris Rogers , an American electrical pioneer who was then chief 
electrician for the Capitol, wrote: "My invention consists in throwing a 
message sent from any transmitting instrument through two or more 
circuits alternately in rapid succession . . . in such a manner that 
anyone tapping but one of the circuits is unable to obtain anything but a 
confused and unintelligible series of signals. . . . The two or more lines 
on which a signal is transmitted according to my plan may be carried to 
a common terminus by widely different routes, and thus it will be 
impossible for any person wishing to do so to ... or tap both lines at the 
same time." 
Later methods operate more directly on the speech itself, often in 
ways that resemble transposition, substitution, and null ciphers. In most 
of the substitution systems, ciphony selects one component out of the 
many that make up the complex phenomenon of speech and alters it. It 
usually chooses frequency, though some scramblers distort volume. 
Frequency here refers to the number of times the vocal chords vibrate; it 
is usually stated in terms of cycles per second, or c.p.s., so that a 
frequency of 500 c.p.s. means that the vocal chords are vibrating 500 
times a second. Because of the resonance of the vocal organs, most 
sounds in speech combine several frequencies, and each sound has its 
distinctive combination of frequencies. The main frequency of the /e/ 
sound in "feel," for example, is much higher than that of the /ii/ sound 
in "fool." Naturally, the absolute frequencies will differ somewhat from 
Person to person, but it is the relative variations within 
an individual's speech that carry much of its information content. 
Ciphony seeks to conceal this content by shifting the frequencies of 
the sounds of speech. It can do this because the telephone first converts 
these sounds into a fluctuating electrical current, which the tubes, 
switches, filters, and circuits that comprise a scrambler then modify 
according to well-known principles of electricity.* Though this current 
may be, transformed in a great variety of ways, many affect the voice 
essentially alike, so that there are relatively few basic scrambles. 
The simplest is inversion. This turns the voice upside down. Though 
normal speech ranges from about 70 to about 7,000 c.p.s., the 
telephone, for engineering reasons, responds only to sounds from about 
300 to 3,300 c.p.s. It is this frequency band that is inverted . A voice tone 
of 300 c.p.s. will emerge from the inverter at 3,300 c.p.s., and vice versa. 
A tone of 750 c.p.s. will become 2,250 c.p.s., and again vice versa. It is 
the equivalent of a = z, 
b = Y.....z = A, a phonetic atbash. Inverted speech 
sounds like a thin high-pitched squawking, ringing with bell-like 
chimes. The word company resembles CRINKAN-OPE, Chicago, SIKAYBEE. 
The inversion pivots in the middle of the frequency band, which means 
that tones in this area somersault through a narrow range. A frequency 
of 1,625 will become 1,675. This relative lack of change results in the 
phenomenon that the word inverter itself, which is composed largely of 
such tones, emerges from the enciphering process that it describes 
almost unchanged! 
Another simple technique is the band-shift. This is a kind of 
telephonic Caesar substitution, in which all the frequencies are shoved 
upwards or downwards a certain distance, with the portion pushed out 
of the frequency band reentering at the bottom or the top. For example, a 
factor of 1,000 might be added to all frequencies in the 300-to-3,300 
band, so that a tone of 500 c.p.s. would be 
*It does not seem possible to devise a scrambler that distorts the 
sound itself (i.e., the vibrations in the air) because, once the waves were 
degraded by, say, some kind of baffle, they could not be restored to their 
original form. Transposition systems, on the other hand, might be 
possible in a very crude form by means of mechanical phonographs. 
From a practical point of view, however, nonelectrical scramblers may be 
ruled out. None ever seems to have been constructed. 
tJtlNSUKS,   S^KAJVLBLtKB,   AIN1J 
shifted to 1,500. One of 2,800 c.p.s. would then be enciphered to 800. 
Band-splitting splits the frequency band into several smaller bands 
and interchanges these. Filters can divide a 250-to-3,000 band into five 
subbands of 550 cycles each: subband A of 250 to 800, subband B of 800 
to 1,350, subband c of 1,350 to 1,900, subband D of 1,900 to 2,450, and 
subband E of 2,450 to 3,000. Then the scrambler's switches and circuits 
may replace A by c, B by D, c by E, D by A, and E by B, thus jumbling the 
normal tones. The better band-splitters shift these substitutions every 
few seconds or milliseconds. The result sounds something like a 
recording of a Mah-Jongg game played too fast. 
Masking systems bury the voice signal in noise. The music from a 
phonograph record can be electrically superimposed on the voice, 
drowning it out. The descrambler, which must have an identical disk 
precisely synchronized with that of the scrambler, subtracts the 
phonograph signal out, leaving the voice. These systems resemble null 
ciphers, which interlard the true message within a welter of spurious  
symbols. Another system is wave-form modification. A fluctuating 
electrical current operates upon the voice current to produce rapid and 
extreme variations in the amplitude of the transmitted speech. This 
sounds rather like a radio whose volume control is being turned up to 
full blast one instant and then down to a whisper the next. In the 
descrambler, an identical synchronized current reverses these effects. 
All these encipherments transform the speech only in the frequency 
dimension, along the vertical axis, as it were. None extends horizontally 
along the time axis. Systems that encipher by changing the temporal 
relationships of speech's continuous flow must preserve it momentarily 
to permit the transposition. Usually they have used magnetic tape. 
Time-division scramble, or T.D.S., chops the stream of speech into 
split-second portions and shuffles them. It does so by tape-recording the 
voice and then picking off segments in jumbled order, using, say, five 
pickup heads fhat a mechanism activates in mixed sequence. The result 
18 a literal  hash of sounds. The descrambler uses five recording heads to 
lay the sounds back on a moving tape m their proper order. Another 
tape-based scramble, the 
wobble, slides a pickup head back and forth along ft,; length of the 
tape as the tape passes beneath it. As tK: head moves opposite to the 
tape's direction, it will re off the signals faster than, they were recorded, 
and the ; will sound higher than normal. As the head moves wi the tape, 
it will read off the signals more slowly than tht were recorded, and these 
will sound lower than norm, \ The result will be an alternation of 
squeaks and grow-sounding exactly as if a phonograph record were 
alternately raced and almost stopped. 
Most of the basic scrambler systems were invented during the 1920s 
and 1930s by engineers for the growing radio and telephone companies. 
A need for them first became apparent when the radio hams began 
listening in to the conversations of erring husbands and their wives and 
on stockbrokers giving tips on the first public radiotelephone service, 
offered after World War I by the Pacific Telephone Company between Los 
Angeles and nearby Catalina Island. The American Telephone & 
Telegraph Company installed an inverter. While it prevented casual 
eavesdropping, it would not keep a determined amateur from inverting 
the inversion. And several did just that on the East Coast in the latter 
1920s when the telephone company was setting up its radiotelephone 
link to Europe. Among them was a young man of 20, William Roberts of 
Trenton, who even sold some of his "De-Scramblers" to Latin American 
countries. 
Growing realization of the insecurity of the inverter caused its 
replacement by band-splitters on both the A. T. & T. transatlantic 
radiotelephone circuit and the Radio Corporation of America's circuit 
between San Francisco, Honolulu, and Tokyo. Called the A-3, this Bell 
Telephone device not only switched the substitution assignments for its 
five subbands but inverted them as well. However, of the 3,840 possible 
combinations, only 11 were considered suitable for privacy, and of these 
only 6 were actually used. They were brought into play in a cycle of 36 
steps, each of which remained for 20 seconds, giving the A-3 an overall 
period of 12 minutes. It began operating betwee the R.C.A. post in San 
Francisco and the Mutual Tel-phone Company post in Honolulu in 
December, 1937-and a few days later the Tokyo post, which was still 
using the old inverters, asked what kind of system was in use on the 
other leg of the circuit, since they could not understand 
it. The military took the query as proof that Japan was monitoring the 
mainland communications. 
It was the A-3 that brought news of World War II to President 
Roosevelt, who was awakened early on the morning of September 1, 
1939, by a call from the American ambassador in Paris, William C. 
Bullitt. As the United States was drawn closer and closer to war, the 
President conferred with his emissaries abroad more and more by 
scrambler radiotelephone. During the Battle of France he sometimes 
spoke with Bullittt several times a day. Characteristically, Roosevelt liked 
the telephone because it cut through the red tape of diplomatic routine 
and the delays of coding and cabling and because it gave him personal 
contact with the speaker. Occasionally he spoke' with Premier Paul 
Reynaud, and frequently and increasingly with Churchill. 
The President's words sped from the White House to the overseas 
switchboard in an A. T. & T. building at 47 Walker Street, New York. In 
common with all other transatlantic conversations, the nasal Roosevelt 
drawl then entered a special locked room, barred to all except 
government-licensed employees, where the A-3 equipment mangled it. 
Here engineers watched dials and listened to the sound to make sure 
that the speech was properly scrambled. At the transmitter, channel 
mixers continually shifted the transmission from one frequency to 
another, so that anyone listening on one circuit would hear it go 
suddenly blank. 
And someone was indeed listening. The Deutsche Reichspost—which, 
like other European post offices, handled telephone and telegraph traffic 
as well as mail—-realized that the only telephone link between England 
and the United States was the radio circuit, and it reported "The special 
national political importance of this communication connection has 
caused the D.R.P. to try with all available scientific means to decipher 
the conversation carried on this connection." A task force under Postal 
Counselor Graduate Engineer Vetterlein of the D.R.P.'s 
Forschungsanstalt ("Research Bureau") set to Work on the problem. The 
engineers soon learned the nature of the A-3 system and found that they 
had to wire circuits for only the six different combinations of subband 
substitutions. Naturally, they had to experiment to find the exact 
subband divisions and the sequence in which 
I 
the six. combinations were used, but from start to finish the solution 
took only a few months. They completed it by September, 1941. Within a 
few more months the D.R.P. had established an intercept and voice-
cryptanalysis station on the Dutch coast. Its elaborate equipment 
instantaneously unscrambled the conversations, losing only a syllable or 
two after a key change until the proper one was found. When this was in 
operation, the German Postal Minister, Wilhelm Ohnesorge, notified Adolf 
Hitler: 
 
THE REICHSPOST MINISTER                                                            BERLIN W 66, 
6 March 1942 
LEIPZIGER   STR.    15 
U5342-1/1 Bfb Nr. 23 gRs   SECRET REICH MATTER  
Decipherment of the U.S.A.-England telephone connection 
Mein Führer ! 
The Forschungsanstalt of the Deutsche Reichspost has 
completed as the latest of its enterprises an intercept installation 
for the telephone traffic between the U.S.A. and England, which 
has been made unintelligible using all present knowledge of 
communications technology. Thanks to the devoted work of its 
scientists, it [the D.R.P.] is the only place in Germany that has 
succeeded in making the scramble, which had been made 
unintelligible with the best methods, again understandable at the 
instant of its reception. 
I will give the results of our interceptions to the Reich Leader of 
the S.S., Party Comrade Himmler, who will submit them on March 
22. 
I will limit the circulation of this communication pending higher 
decision in view of the fact that if this success were to come to the 
knowledge of the English, they would further complicate the 
problem of telephone traffic and cause it to be sent on the 
telegraph cable. 
Heil mein Führer! 
(signed)  Ohnesorge 
 
To the 
Leader and Reich Chancellor o 
f the Greater German Reich  
Berlin W8 
Dr. Ohnesorge appended a concrete example of the intercept station's 
success: a cryptanalyzed and translated conversation plucked from the 
ether at 7:45 p.m. September 7, 1941. A Briton who had just arrived in 
the United States was talking with a colleague back in England about the 
need for a man named Campbell to have an assistant and about their 
propaganda bureau. 
The group continued to send transcripts to Hitler's desk, including a 
1942 chat between Churchill (at Whitehall 4433) and a Mr. Butcher in 
New York, and one between Major General Mark Clark and the Inspector 
General's office in Washington. 
 
[Codebreakers 297.jpg]
Transcript of a German descrambling of an intercepted Churchill transatlantic 
conversation 
At 1:00 a.m. July 29, 1943, they hit the jackpot: a radiotelephone 
conversation between Roosevelt and Churchill. They were discussing the 
coup in Italy that had just ousted Mussolini's government: 
"We do not want proposals for an armistice to be made before we have 
been definitely approached," said Churchill. 
"That is right," agreed Roosevelt. 
"We can also wait quietly for one or two days." 
"That is right," said Roosevelt again. 
Churchill said that he would contact the king of Italy, and Roosevelt 
replied that he too would get in touch with " Emmanuel ." "I do not know 
quite how I shall do this," he admitted. The Germans took the 
conversation as evidence of the treachery and complicity of the Italians: 
"This is complete proof that secret negotiations between the Anglo-
Americans and Italy are under way," the war diary of the O.K.W. noted. 
This does not seem to have been the case; in any event, the Allies were 
cool to the coup. 
Later the Forschungsanstalt again picked up a Roosevelt-Churchill 
conversation—Churchill was practically addicted to the telephone, calling 
Roosevelt at all hours from his bombproof shelter in Whitehall, and 
placing great faith in the scrambler. This conversation, early in 1944, 
"lasted almost five minutes," wrote Walter Schellenberg, the Himmler 
aide who studied it, "and disclosed a crescendo of military activity in 
Britain, thereby corroborating the many reports of impending invasion." 
Soon thereafter the A-3 was replaced by a more secure system, and 
English became Greek to the listening Germans. 
 
15. The Scrutable Orientals 
 
FROM THE SUNDAY morning when Commander Mitsuo Fuchida, in his 
bomber high over Pearl Harbor, radioed "TORA, TORA, TORA!" to indicate 
that his attack force had achieved complete surprise, the gods of war had 
smiled without surcease upon the armed forces of imperial Japan. The 
strike at Pearl Harbor had decimated the United States fleet. 
Unhindered, the Greater East Asia Co- 
Prosperity Sphere expanded rapidly and uninterruptedly. Guam was 
captured on December 10, Wake on the 23rd . Two days later Hong Kong 
fell. Japanese aircraft sank Prince of Wales and Repulse, giving Winston 
Churchill his worst shock of the war and leaving the whole western 
Pacific, the Indian Ocean, Oceania, and even Australia virtually 
undefended by naval forces. Tojo's armies overran Singapore and Malaya 
with its rubber plantations, then the Dutch East Indies with its great oil 
fields. Siam and the Solomons were in their hands. China was under 
blockade. In May the Philippines surrendered. Within six stupefying 
months, the Rising Sun shone upon nearly a tenth of the globe's surface. 
Nippon's enemies had been wiped from the seas. Her troops raped and 
pillaged from bustling Rangoon to the languorous South Sea islands. It 
was the most rapid conquest in history. 
It amply fulfilled the Japanese war plan. Japan did not intend to 
invade the United States. Rather, she planned to feed upon the riches of 
the conquered territories behind a ring of impregnable defense positions, 
from which she would beat off any attacker. But the high command, 
bedazzled by success and greedy for more, decided instead to continue 
the sweep before its momentum was lost. The admirals and generals 
pointed out that naval losses, which they had anticipated at 25 per cent, 
had been infinitesimal. The largest ship sunk had been a destroyer, and 
so more than adequate forces remained for the new drive. Furthermore, 
they reasoned, the defense perimeter would be protected as much by 
greater depth as by greater consolidation. They therefore set in motion 
two ambitious plans. One was an amphibious assault southward to Port 
Moresby, a town on the southeastern tip of New Guinea only 400 miles 
from Australia . The other pivoted on Midway, a tiny atoll in the middle of 
the Pacific that stood as a sentinel to Hawaii. 
This second plan had two parts. The first part aimed at the atoll's 
capture. Its two coral islets—the larger barely two miles long—possessed 
no intrinsic worth but great strategic value, for whoever held them 
controlled the central Pacific and hence the approaches to either end of 
the oceanic basin. The second and more important part of the plan 
sought to lure out the remainder of the American fleet and destroy it. 
Admiral Isoroku Yamamoto, Commander in Chief of Japan's Combined 
Fleet, appreciated 
America's industrial might and realized that Japan had to win 
quickly—before America could bring it to bear. He also knew that the 
United States could not let Midway go by default, as it had Wake and 
Guam. When the Pacific Fleet, enfeebled by the losses at Pearl Harbor, 
steamed out to defend the atoll, he would fall upon it with his vastly 
superior forces and annihilate it. This final disaster would convince 
Americans that Japan could not be beaten . They would therefore quit a 
pointless struggle and leave Japan master of the western Pacific. Or so 
the warlords purposed. 
They did not know that the United States had fashioned a secret 
weapon of such potency that it could alter the balance of power in the 
Pacific. It was located in the long, narrow, windowless basement of the 
14th Naval District's Administration Building in the Navy yard at Pearl 
Harbor. VaultHke doors protected its secrets; steel-barred gates at the 
top and bottom of the stairs kept out visitors; guards stood a round-the-
clock watch. This office was staffed, when the war broke out, with about 
30 officers and men. It was equipped with International Business 
Machine Corporation tabulators, which were partitioned off in a separate 
section because of the racket they made. Its raw material came in by 
courier from the radio intercept station at Wailupe. This was the so-
called Combat Intelligence Unit, the radio intelligence organization that 
served the Pacific Fleet. 
Lieutenant Commander Joseph John Rochefort had commanded it 
since May of 1941. Before Pearl Harbor, the bulk of its personnel worked 
on interception, direction-finding, and traffic analysis; the unit fed these 
results to the fleet intelligence officer. Though one of its young crypt-
analysts, Chief Radioman Farnsley C. Woodward, had attacked the 
Japanese diplomatic systems in use by the Honolulu consulate as a favor 
for counterintelligence, the unit's main cryptanalytic duties before Pearl 
Harbor involved the solution of the Japanese flag officers' system and 
miscellaneous administrative, personnel, and meteorological codes. It 
had only three real cryptanalysts to handle this workload, Rochefort and 
Lieutenant Commanders Thomas H. Dyer and Wesley A. Wright. The 
others were trainees, aides, clerks, and translators. Since August of 1941 
it had been working a seven-day week; in October it 
went to a night watch as well—the only unit in Pearl to do so. 
Three days after Pearl Harbor the unit was given a major change in 
assignment. It was to discontinue work on the flag officers' system (which 
was to be analyzed in OP-20-o in the Navy Department in Washington) 
and to join in the attack and breakdown of the Japanese fleet 
cryptographic system, dubbed JN25 by OP-20-G. This most widely 
distributed and extensively used of Japan's naval cryptosystems, in 
which about half her naval messages were transmitted, was already the 
target of three other cryptanalytical units—a 16th Naval District group 
under Lieutenant Rudolph J. Fabian on Corregidor, a British group at 
Singapore, and OP-20-o. They had determined that it was a two-part 
code of about 45,000 five-digit groups, enciphered by two volumes of 
50,000 five-digit additives each. The b, or second, edition had come into 
force on December 1, 1940, and by the following November messages in 
it were partly readable. At 6 a.m. on December 4, 1941, new additive 
books came into effect, together with new indicators. Fabian's group 
broke into this new encipherment four days later, and by Christmas  
messages were again being read as before. But these readings were 
tantalizingly fragmentary, and much remained to be done. 
The commencement of hostilities generated an enormous increase in 
radio traffic and consequently in the workload of the Combat Intelligence 
Unit. To handle it, the unit dragooned personnel from every possible 
source. It first acquired the band of the U.S.S. California, which had been 
badly damaged in the first few minutes of the air attack. Dyer threw up 
his hands when he heard about it, but music and mathematics and 
cryptanalysis seemed to go together,* and nearly all the bandsmen 
proved above average and some exceptional in their new tasks. By May, 
the basement office contained about 120 persons. Of these, perhaps half 
a dozen were by then fairly competent crypt-analysts, 50 were beginning 
to get the feel of the work, and the remainder were clerks. Work went on 
round the clock in the air-conditioned basement, but the unit was 
woefully understaffed. 
*As corroboration, it might be noted that Painvin won a prize as a 
young ' cello player, that Mauborgne and Kunze both play the violin at 
least passably, and that an English expert taught music. 
Rochefort virtually lived in that cellar for the first three months. He 
supervised the entire operation—interception, traffic analysis, 
cryptanalysis, translation. Dyer, his immediate subordinate, was in 
charge of the cryptanalytic section. A slender man just turning 40, with a 
mild, friendly personality but a tough and unrelenting mind, Dyer had 
come to the Islands in 1936 and had begun cryptanalytical work largely 
on his own initiative. He had become interested in the field soon after his 
graduation from Annapolis in 1924. Assigned to New Mexico as an 
assistant radio officer, he began doing the cryptograms in the naval 
communications bulletins, which intrigued him, and then read 
Friedman's Elements of Cryptanalysis, which hooked him. In 1931, he 
succeeded Safford as head of the Research Desk in the Code and Signal 
Section of Naval Communications, commanding the entire U.S. Navy 
crypt-analytical group of four people, clerks included. 
The following year, Dyer became the father of machine cryptanalysis 
when he installed I.B.M. machines to speed up solution. (The Army did 
not begin using the machines for cryptology until 1936.) In 1937, after he 
had been in Hawaii for a year, the Navy sent some I.B.M. machines out 
to him and assigned him a yeoman to expand, in a modest way, the 
cryptanalysis that he had been doing. Those machines were his baby. 
While other cryptanalysts used pencil and paper to test assumptions, 
Dyer tried them out directly on the machines—and worked more quickly 
that way than he could have by hand. He stayed in cryptanalysis all 
during the war, winning the Distinguished Service Medal, and even 
afterward, rising to a captaincy. On his retirement from the service in 
1955, he started teaching mathematics at the University of Maryland. 
His chief assistant was Wright, who handed out the work that Dyer 
wanted done and then pitched in himself. In 1929, three years after he 
graduated from Annapolis, he found himself with his crew on a rifle 
range shared by Safford, a fellow officer in a destroyer division. Like 
Dyer, he had solved the ciphers in the communications bulletins, and 
Safford, in a sales campaign that began to the crack of musketry, 
convinced him that he should specialize in cryptology. But it was not 
until June of 1933 that Wright began his first tour in communications. 
Sea duty alternated with cryptologic work until, in March of 1941, he 
went to Pearl Harbor with Admiral Kimmel as the cryptanalyst in 
1±1±J SUKUlABUi UKliJNTALS       303 
a. fleet security unit. He immediately began working with the Combat 
Intelligence Unit and in February of 1942 was formally transferred to it. 
He was then 39, a broad-shouldered redhead with craggy features and 
big hands whose strong resemblance to a tugboat captain—his nickname  
is "Ham"—belies his gentle manner and his courtesy. He too remained in 
cryptology throughout the war, winning the Legion of Merit; like Dyer he 
stayed in it afterwards, winning a gold star to his Legion of Merit. He 
retired in 1957. 
With the entrance of the Rochefort group into the fray against jN25b, 
the three Allied cryptanalytic units in the Pacific and OP-20-G in 
Washington began working in the closest possible cooperation. Positive 
or tentative codegroup recoveries were flashed from unit to unit via the 
intercept channel for MAGIC. Each unit intercepted messages that the 
others might not have picked' up, and so could make new assumptions 
or confirm or disprove old ones. Washington, which had the most 
equipment and the largest staff, seems to have led in the work of 
stripping the additive groups. The Singapore and the Philippines units 
had made the difficult initial entries, but their work was interrupted 
when the British had to move to Colombo and Fabian was evacuated by 
submarine from Corregidor in February, 1942, several weeks before 
MacArthur. Aside from a few such generalized observations, it is almost 
impossible to say which group, much less which individual, deserves the 
major share of credit for solving the edition of the fleet cryptographic 
system then in force. Collaboration was too intimate. A possibility raised 
in a discussion between Dyer and Wright might be developed into a 
probability by a check of messages in Washington and verified by a new 
intercept at Colombo. 
Meanwhile, the Japanese—who had no suspicion of all this activity—
felt a vague unease at the extreme length of service of this code. A new 
edition, which would be called JN25c by the Americans but was called 
the Naval Code Book D by the Japanese, was to be placed in service April 
1. But administrative confusion in the Navy libraries , which had custody  
of the codebooks, plus difficulties in physically distributing the books by 
destroyer and airplane to moving ships and widely dispersed 
installations, forced a postponement to May 1. Consequently, the 
American cryptanalysts could tunnel ever more deeply into JN25b. 
Gradually the isolated fragments of plaintext that they were 
recovering grew denser, enlarged, touched, made sense. Parts remained 
unread, but the large patches of coherence offered clues to Japanese 
thoughts and plans. Hence it was that by April 17 the cryptanalysts 
smoked out the gist of the Japanese plan to seize Port Moresby and 
threaten Australia. The new Commander in Chief of the Pacific Fleet, 
Admiral Chester W. Nimitz, dispatched two carriers, Lexington and 
Yorktown, to spoil it. 
This task force, commanded by Rear Admiral Frank Jack Fletcher, 
began cruising the lovely waters of the Coral Sea off the northeast coast 
of Australia in search of the enemy. At 8:15 a.m. May 7 a message from a 
Yorktown search plane was decoded as reporting the discovery of "•two 
carriers and four heavy cruisers" 175 miles northwest of the American 
force. Fletcher thought that this was the main Japanese force covering 
the amphibious landing and flew off two deckloads of planes to attack it. 
When the search pilot returned, it was discovered that the "two carriers 
and four heavy cruisers" had resulted from a disarrangement of his 
codepad; they should have been reported as "two heavy cruisers and two 
destroyers." But another contact report alerted the fliers to the presence 
nearby of the landing force itself, escorted by the light carrier Shoho. 
They swarmed over Shoho and sank it in ten minutes—a record for the 
war. " Scratch one flattop!" exulted one pilot. The transports, shorn of 
their air cover, retired to the northward. This accidental attack on the 
wrong force thwarted the main Japanese objective and, since the 
transports never again entered the Coral Sea, lifted the threat of invasion 
from Australia. 
Fletcher could hardly foresee this, however, and next day he located 
the main Japanese force of two big carriers and attacked them at the 
same time that they spotted and attacked him. It was the first naval 
battle in history which was fought entirely by air and in which the 
opposing ships never even sighted each other. One Japanese carrier was 
put out of action; the other had its flight deck bent so that it could not 
recover all its planes, many of which had to be jettisoned. But Yorktown 
was scarred and the beloved  Lexington so badly damaged that, after futile 
attempts to save her, she had to be torpedoed by an American destroyer. 
Though this gave the Japanese a tactical victory in the Coral Sea, they 
had lost strategically. More important, 
their two damaged carriers would not be present at the Midway battle. 
For the check at the Coral Sea had not altered Japan's grandiose plans 
for winning the war against America. 
During these hectic spring days, the cryptanalysts strained under 
high pressure. Rochefort and Dyer alternated 12 hours on, 12 hours off. 
Speed was emphasized. As the meaning of a codegroup became known in 
the Combat Intelligence Unit, whether through its own efforts or by a 
helpful message from another unit, the codegroup and its meaning were 
punched on an I.B.M. card and stored in the machine. When an intercept 
came in, a clerk would punch its codegroups on I.B.M. cards and feed 
them in. The machine automatically made the run of repeated 
subtractions and the check of its mechanized difference "books" 
necessary to find the identical remainders, and then, with human 
guidance, the runs to reconstruct the relative additive sequence, correct 
it to the absolute sequence, and strip it from the encicode message. This 
machine would then compare the placode groups with the decode cards 
in its storage and print out the plaintext for whatever decode cards it 
had. Presumably it would also print out the various possibilities in the 
case of garbled or partial codegroups. It could also make frequency 
counts and contact counts and on command could disgorge a desired set 
of statistics—all codegroups preceding and following a given codegroup, 
for example. Head of the I.B.M. room, which was constantly being 
enlarged, was Lieutenant Commander Jack S. Holtwick, Jr., a 1927 
Annapolis graduate who had done cryptologic work at the Navy 
Department, the 16th Naval District, and the Asiatic Fleet from 1934 to 
1939; he had reported to the Hawaiian unit in June of 1940. 
Not every cryptogram was decrypted. Japanese traffic was too heavy 
for the undermanned Combat Intelligence Unit. All major and most 
minor Japanese fleet circuits were monitored, and the messages that 
were driven down by car from the intercept stations were scrutinized by 
traffic analysts. From such indications as the length of a message, its 
originator, the time of day at which it was sent, the circuit used, the 
addressees, and stereotypes in the text of the cryptogram itself, plus an 
intuitive "feel" based on day-in, day-out listening-in to Japanese 
communications, these "scanners" could pick out the important 
messages. 
The cryptanalysts concentrated on these, filling in missing additives 
and conjecturing the meaning of new codegroups. They seldom read 
messages "solid"; even the translators— who were half cryptanalysts—did 
not fill in all the holes. 
As these translations were written up, Lieutenant Commander W. J. 
( Jasper ) Holmes brought them, blank spots and all, together with some 
that were very sketchy indeed, to Nimitz' chief of staff, Rear Admiral Milo 
F. Draemel, who took the important ones in to Nimitz himself. Holmes 
had retired in 1936 with an arthritic back but had returned to active 
service after Pearl Harbor. He was a good enough writer to have sold 
several pieces on naval subjects to The Saturday Evening Post, the 
toughest magazine market in America, and he used this literary ability in 
collaborating with the fleet intelligence officer in pulling together 
information from sightings by U.S. submarines, traffic analysis, and 
comparison of many intercepts into an intelligence compendium that 
went to the higher-ups. 
On May 5,* Imperial General Headquarters issued Navy Order 18: 
"Commander in Chief Combined Fleet will, in cooperation with the Army, 
invade and occupy strategic points in the Western Aleutians and Midway 
Island." Wireless traffic subtly changed its character. More than 200 
ships would take part in the operation, and though most were already in 
the Inland Sea, many of the carriers, battleships, submarines, 
minesweepers, transports, and supply vessels had to be summoned from 
missions at sea. Some had to be refitted, and messages crackled to and 
from the naval base at Kure. The magnitude of the supply problem alone 
was indicated by the fact that this one operation would consume more 
fuel and cover a greater mileage than the entire Japanese Navy had done 
in any previous peacetime year. The battle preparations called for the 
ships to assemble in Hiroshima Bay and then to sortie in five main forces 
over a four-day period according to a precisely calculated schedule. The 
directives, queries, and responses involved in organizing so complex an 
operation filled the airwaves. Coded messages streamed out of 
Yamamoto's headquarters aboard Yamato, the world's largest battleship. 
And not only the legitimate recipients were reading them. 
For the effective date of the new edition of the fleet cryptographic 
system, which had been postponed once 
*A11 times are local times. This would be May 4 in Hawaii. 
from April 1 to May 1, had to be again set back another month, to 
June 1. Perhaps the very extent of the Japanese conquests defeated their 
distribution efforts. These may not have been very energetic in any case, 
for the Japanese, while paying lip service to the need for communication 
security, seemed to believe, on the evidence of their military successes, 
that their codes were not being broken and that timeliness in their 
replacement was not really necessary. By early May, Allied cryptanalysts, 
who had recovered about a third of the JN25b lexicon, could read about 
90 per cent of an ordinary cryptogram (because the recovered codegroups 
were the most frequently used). Had Japan changed her main naval code 
on May 1 as scheduled, she would have blacked out Allied cryptanalysts 
for at least several weeks—weeks that, as it turned out, were to be 
crucial to history. 
Her failure to do so meant that she was masking her Midway 
preparation messages behind a cryptographic smoke screen that 
American cryptanalysts had almost entirely blown away. And as 
solutions of these messages drifted into Nimitz' office in the first weeks of 
May, that old sea dog scented a major offensive. Hastily, he recalled 
carriers Hornet and Enterprise, which had headed for the Coral Sea after 
launching Jimmy Doolittle 's raid on Tokyo, and Yorktown, to be ready for 
any eventuality. But what eventualities were possible? The Fleet 
Intelligence Summary of May 15 warned of an enemy raid or seizure of 
Dutch Harbor in the Aleutians some time between May 30 and June 10. 
This was almost certainly a diversionary move. But where would the 
main Japanese attack fall—and when? There was no clear-cut answer. 
Several Japanese strategies appeared possible. Nimitz himself thought 
Midway was the target, but in Washington Admiral Ernest J. King, Chief 
of Naval Operations, who was working from essentially the same 
information, concluded that Oahu was. 
Yamamoto was well aware of the inestimable advantage of surprise, 
that element of warfare which so often decides the course of battle. He 
felt confident that the United States, unable to defend all points, would 
have to counterattack at a time and place governed by the Japanese 
moves, giving Yamamoto control of every situation. In addition to this 
tactical initiative, he had an overwhelming preponderance of forces. To 
his 11 battleships, 5 carriers, 16 cruisers, and 49 destroyers, Nimitz 
could oppose no battle- 
ships and only 3 carriers, 8 cruisers, and 14 destroyers. 
On May 20, Yamamoto issued an operations order that spelled out in 
detail the tactics to be used in the Midway assault. It was to begin on 
June 3 with a diversionary attack on the Aleutians. With Nimitz' forces 
thus pulled off balance, the softening-up would begin on the Midway 
defenders, to be followed on June 6 by a dawn assault. When the Pacific 
Fleet either hurried south from the Aleutians or sallied forth from Pearl 
Harbor to defend Midway, the numerically superior bombers and torpedo 
planes of the Japanese force would cripple it. Then Yama-motb's 
battleships and heavy cruisers would move up to sink its remnants by 
gunfire. The work of December 7 would be completed; a Japanese 
Midway would rule the Pacific, threatening Hawaii itself; and the war 
would be as good as won. 
Unknown to Yamamoto, his order was also picked up by the Allied 
listening posts that ringed the Pacific. Its extreme length indicated its 
importance, and Fabian's unit, by this time in Melbourne, may have first 
suggested that it might be an operations order. But the Hawaii unit put 
out the first fragmentary solution. The I.B.M. apparatus rapped it out in 
a mechanical cryptanalysis for as much of the intercept as codegroups 
and additives were available in storage. Only about 10 to 15 percent of 
the message was lacking, and the unit began a massive effort to fill in 
these holes. This task lasted more than a week. Dyer pushed cards 
through the clacking machines. The. fledgling crypt-analysts drove 
pencils furiously across sheet after sheet of paper. The clerks scurried 
among the desks. Overworked language officers sucked in Japanese 
through their eyes and spouted English at their fingertips. Gradually 
additives were recovered and stripped and the plaintext of the uncovered 
codegroups was revealed or inserted. As each new portion came to light, 
adding another scrap of information, it was rushed upstairs to Jasper 
Holmes. He would write it into its proper place in the picture and send it 
along to Commander Edwin T. Layton, the fleet intelligence officer, for 
transmission to Draemel and Nimitz. The operations order was so long 
and so detailed that dozens of such fragments rustled across the 
commander's desk. 
Still in doubt, however, were its most important parts: the dates, the 
times, and the places of the various operations. The date-time 
information had been superenciphered 
in what appeared to be a polyalphabetic system. This had never been 
solved because it had been observed only three times before, and one 
occasion had a garble that threw sand in the gears of every attempted 
reconstruction. The crypt-analysts had considered that they could not do 
anything with this, and so, rather than waste a man on a fruitless 
endeavor, all hands concentrated on the body of the message. Additives 
and codegroups recovered there would be of value in later solutions. 
Consequently, the question of when was left to other branches of naval 
intelligence, which applied ship speeds and similar data to estimate the 
date and time for the attack. 
The question of where was answered fairly quickly by the Combat 
Intelligence Unit. The Japanese indicated geographic locations by maps 
with coordinates in code; they called these their CHI-HE systems, and they 
served as much to avoid error in transliterating kata kana as to conceal. 
The cryptanalysts had partly recovered one such map; they knew the 
designators for Pearl Harbor, for example. Several weeks earlier, they had 
discovered the code coordinates AF in a message sent from two scout 
planes over Midway. Context suggested that AF meant Midway. When 
they checked this against their partially solved map grid, they found that 
A'S representing one coordinate of Midway's position and F'S representing 
the other fit into it perfectly. So when they saw that AF was the codegroup 
for the locus of the main attack, they felt quite sure that Midway was the 
target. 
But the top brass squinted at this identification. On it rode the very 
existence of the American fleet and the future course of the whole Pacific 
war. They demanded confirmation. 
Rochefort decided to trick the Japanese into giving him the proof. He 
cooked up the idea of having the Midway garrison broadcast a distinctive 
plain language message which would presumably be picked up by 
Japanese monitors. Their coded report would be intercepted and solved 
by Americans, and the geographic indicator that they used in this telltale 
dispatch would have to mean Midway. Layton liked the idea, and the two 
men drafted a message in which Midway reported that its fresh-water 
distillation Plant had broken down. They cabled it to the atoll with an 
order to radio it back to Pearl in clear. Midway complied. The 
cryptanalysts waited. Two days later there appeared in 
the harvest of Japanese intercepts one stating that AF was short of 
fresh water. 
By about Wednesday, May 27, Nimitz knew almost as much about the 
Midway operation as many of the captains of Japanese warships who 
were to take part in it. In all respects but one his information was solid: 
it had come from the Japanese themselves and had even been verified. 
The one point was the when. His intelligence staff had erected an 
elaborate scaffolding of estimates, deductions, probabilities, and 
predictions to date the operation as beginning against Midway June 3. 
The reasoning was shrewd, but its hypothetical framework could hardly 
have comforted Nimitz in so weighty a matter as much as the repeatedly 
confirmed perceptions of the cryptanalysts. 
Meanwhile, in the basement office, nearly everything that could be 
done to the body of the Yamamoto operations order had been done. 
Hardly any gaps remained, and only an occasional paper went upstairs. 
Intercept importance had fallen off with the sortie of the Japanese fleet 
under radio silence. Late one afternoon in this comparative lull, 
Lieutenant Commander Joseph Finnegan , a 1929 Annapolis graduate 
who had served as a language officer in Japan from 1934 to 1937, 
brought the section with the untouched internal date-time cipher over to 
Wright. 
"Ham," he said, "we're stuck on the date and time." 
Wright had already stood his 12-hour watch and was about to go 
home before returning in 12 hours for another. Instead, he went with 
Finnegan to an empty desk in the traffic analysis section. Finnegan gave 
him the three previous uses of the cipher—one of them in a message that 
had led to the Coral Sea battle, another the garbled text. Wright put four 
people on a search for other instances of the cipher, and he and 
Finnegan set to work. For a good while the flaw in the one corrupt 
cryptogram frustrated their efforts, but as the night wore on Wright 
worked it out. He discovered that the date-and-time cipher comprised a 
poly-alphabetic with independent mixed-cipher alphabets and with the 
exterior plain and key alphabets in two different systems of Japanese 
syllabic writing—one the older, formal kata kana, the other the cursive 
hira gana . Each has 47 syllables, making the polyalphabetic tableau a 
gigantic one of 2,209 cells, more than three times as extensive as the 
ordinary Vigenere tableau of 676 cells. 
Nevertheless, by about 5:30 the next morning he had a 
solution. His inability to apply symmetry of position to the unrelated 
alphabets gave it a certain amount of slack, but he regarded it as 
essentially sound. He showed it to Rochefort. That expert noted the weak 
spots and said to Wright in mock rebuke: 
"I can't send this out." 
"If you don't," Wright replied firmly, "I will." 
Rochefort laughed. He had only been testing Wright's faith in the 
solution, and Wright knew it. "Go ahead," he said. 
Wright took it up to communications for transmission via the secret 
channel to the other communications intelligence units. He then headed 
once again for home, and on the way saw Layton about 7:45 and told 
him about it. Within hours, Nimitz knew that the Japanese had ordered 
that the Midway operation was to commence June 2 against the 
Aleutians and June 3 against the atoll. His intelligence staff had forecast 
correctly—but what a relief it was to know for sure, to work on fact 
instead of on theory. 
By this time—the middle of the week before the attack was due—
Enterprise and Hornet had reached Pearl after racing up from the 
southwest. Yorktown limped in the next day, her bowels torn by a Coral 
Sea bomb. Peacetime structural repairs would have taken 90 days; now 
the Navy yard, goaded by Nimitz, who knew how soon the hammer would 
fall, did the impossible and patched her up in two. On the 27th, Nimitz 
had issued his Operation Plan 29-42, stating that "The enemy is 
expected to attempt the capture of Midway in the near future" and 
setting forth his dispositions for the counterattack. He ordered his 
carriers to a position codenamed POINT LUCK about 350 miles northeast of 
Midway. Here, on Yamamoto's flank, where they were not likely to be 
scouted, they were to await his advance. Then, with the advantage of the 
surprise that the American cryptanalysts had wrestled from the 
unsuspecting Yama- moto , they were to spring on him, repulse the 
Midway invasion, wreak havoc on his carriers, and finally cheat him of 
the naval victory on which his war-winning strategy depended. 
The three carriers took up station at POINT LUCK on June 2. By then 
the Japanese had succeeded in effecting their long-desired code change. 
It completely blacked-out • the cryptanalysts of the Combat Intelligence 
Unit. They began chipping away at what they called jN25c, but they 
I 
got only a few glimmers of light before edition d came into force, 
unexpectedly soon, in August. Had the June change been made in April 
as the Japanese had originally wanted, the cryptanalysts, Dyer said, 
"could not have gotten back in in time to do any good. May 1st would 
have been impossible. Midway was therefore a very close thing." But the 
June change did not affect the course of events, since all plans had been 
made and the great operation had already been set in motion. 
According to program , the Japanese Aleutian force struck first. Nimitz 
had sent a North Pacific Force of cruisers and destroyers to protect his 
flank. Like some other officers, its commander, Rear Admiral Robert A. 
Theobald, suspected that the Japanese had "planted" the information on 
which U.S. intelligence estimates were based. They were probably 
thinking of dummy radio activity to fool the traffic analysts, for Nimitz 
never mentioned the supersecret cryptanalytic successes to his force 
commanders—not even in the briefings just before the battle. The 
suspicions of the doubters may have been reinforced by an intercepted 
plaintext request of a Japanese Army officer that all mail for his unit be 
addressed to Midway after June 5; as General Marshall later said, "that 
seemed a little bit too thick." Furthermore, Nimitz himself warned of 
Japanese trickery when arranging for identification by radio in his 
Operation Plan 29-42: "The Japanese are adept at the practice of 
deception. Have authenticators ready for use when needed. Small craft 
and aircraft except patrol planes use two alternate letters from the 
expression: 'Farmer in the dell .' Example: RE or EL or NH." Hence Theobald 
disbelieved the intelligence supplied him that the Japanese were going 
just to bombard Dutch Harbor but to seize Attu and Kiska. He deployed 
his force to prevent what he was convinced would be an invasion of 
Dutch Harbor. Unfortunately, this disposition deprived him of any 
opportunity to fight when, on the morning of June 3, right on schedule, 
the Japanese did just what the cryptanalysts had said they would do and 
bombed Dutch Harbor, inflicting considerable damage. They escaped 
unmolested. 
The same morning an American search plane from Midway spotted 
the enemy. It was the troop-carrying invasion force, which Midway-based 
planes promptly but ineffectually attacked. The main striking force of 
four big carriers—Akagi, Kaga, Hiryu, and Soryu, veterans of the 
Pearl Harbor attack—remained hidden by clouds until the next 
morning, June 4. Again a Midway scout discovered the vessels. The 
American carriers sped toward them to launch planes for an attack. 
Meanwhile, American bombers from Midway and Japanese bombers from 
the carriers were mounting simultaneous attacks. Neither did much 
damage. Returning Japanese planes told of the need for further attacks. 
So far the Japanese had sighted no American ships. They had not 
been diligently looking for them because, according to their expectations, 
no major enemy forces should have been in the vicinity: they should have 
been in Pearl, waiting to find out where the Japanese would strike. 
Admiral Chuichi Nagumo therefore struck below the 93 planes he had 
prudently held to counter even the highly unlikely enemy naval attack 
and ordered them rearmed for land bombardment. Thirteen minutes 
later he was dumbfounded to receive a report of the sighting of enemy 
ships to the northeast. What should he do? For a precious quarter of an 
hour he mulled it over. Finally he canceled his order and directed the 
planes readied to attack ships. The incendiary and fragmentation bombs 
that the crews had just sweated into the bomb bays had to be replaced 
with the original torpedoes and armor-piercing bombs. Before this work 
was completed, his airplanes began returning from Midway, and his 
carriers had to recover these before launching the others. 
It was at this most vulnerable of m ments—with all planes aboard, 
with fueling in process and bombs and ammunition stacked in the open 
on the hangar and flight decks —that American planes attacked. Three 
waves of torpedo-bombers, one each from Hornet, Enterprise, and 
Yorktown, swept in, suffered heavy losses under Zero attacks or 
antiaircraft fire, and scored not a single hit. The last plane zoomed away 
at 10:24 a.m. This moment marked the high tide of Japan's fortunes in 
World War II. Jubilant officers cheered what they thought was victory at 
Midway, and in the war. Within six minutes, the tide was ebbing. 
Dive-bombers from Enterprise screamed down on Akagi, Kaga, and 
Soryu. One hit set off Akagi's torpedo storage, another exploded amid 
planes being rearmed on her flight deck; flames swept her, and within 24 
hours she had been sunk. Kaga took four hits in rapid succession and 
sank that evening. Yorktown dive-bombers pummeled Soryu 
with three half-ton bombs; within 20 minutes she had to be 
abandoned, and a few hours later was torpedoed by an American 
submarine. The work of December 7 had not been completed, but 
avenged. 
The rest was anticlimax. Later in the day Hiryu was sunk, and the 
Japanese in turn got Yorktown. Yamamoto next day realized that he was 
beaten. He called off the invasion of Midway and retreated, keeping close 
to his cabin on the homeward voyage. The samurai chieftains canceled 
plans for further advances and shifted from offense to defense. The 
failure to destroy the American Navy knocked the keystone from 
Yamamoto's strategy, and his words to Prince Konoye before the war 
haunted him: "I must also tell you that, should the war be prolonged for 
two or three years, I have no confidence in our ultimate victory." And not 
only did American industrial strength rise up like a specter. Japan's lack 
of it meant that she would never recover from the loss of four big 
carriers. The 4th of June had doomed her. 
"Midway was essentially a victory of intelligence," Nimitz has written. 
"In attempting surprise, the Japanese were themselves surprised." 
General Marshall was even more specific. As a result of cryptanalysis, he 
declared, "We were able to concentrate our limited forces to meet their 
naval advance on Midway when otherwise we almost certainly would 
have been some 3,000 miles out of place." The surprise, the 
concentration, were engineered days before in a basement office a 
thousand miles from the scene of the action, where the solution of 
messages in JN25b (abetted by the recoveries of the other cryptanalytic 
units) and its internal time and place ciphers forged effects more crucial 
to the course of history than any other solution except that of the 
Zimmermann telegram. The codebreakers of the Combat Intelligence Unit 
had engrossed the fate of a nation. They had determined the destinies of 
ships and men. They had turned the tide of a war. They had caused a 
Rising Sun to start to set. 
 
There was no single moment when the Battle of Midway was suddenly 
and decisively won, and so there was no burst of wild cheering in the 
basement office. The cryptanalysts reacted prosaically. The unit went on 
a watch in three instead of a watch and watch. It was also expanding 
rapidly. By the next year, it had changed its name to Fleet Radio 
ini-N i/vi^a 
Unit, Pacific Fleet—FRUPAC, in the Navy's interminable list of 
acronyms. Rochefort had departed in October, 1942, for two years of 
noncryptologic duties. He was replaced by Captain William B. Goggins, 
44, a 1919 Annapolis graduate with long communications experience. 
Goggins, who had been wounded in the Battle of the Java Sea, remained 
as head of FRUPAC to January, 1945. Dyer continued to head 
cryptanalysis. Eventually FRUPAC comprised a personnel of more than 
1,000. Much of the work was done in the new Joint Intelligence Center, 
housed in a long narrow building across Midway Drive from Nimitz' 
headquarters perched atop a cliff overlooking Pearl Harbor. Fabian, in 
Melbourne, directed a field unit similar to FRUPAC. He was on the staff of 
the Commander in Chief, 7th Fleet, which was attached to MacArthur's 
South West Pacific Area command. 
FRUPAC'S growth mirrored that of all American crypt-analytic agencies. 
This expansion compelled OP-20-o to reorganize as early as February, 
1942. The workload had become too heavy for one man (Safford). The 
outfit was split up into sections for its three major cryptologic functions : 
(1) the development, production, and distribution of naval cryptosystems, 
headed by Safford; (2) policing of American naval communications to 
correct and prevent security violations; (3) cryptanalysis, headed by 
Commander John Redman. In September the development function was 
separated from the production. Safford retained control of the 
development work until the end of the war, devising such new devices as 
call-sign cipher machines, adapters for British and other cryptographic 
devices, and off-line equipment for automatic operation. About June, the 
Navy ceded Japanese diplomatic solutions to the Army, giving over its 
files as well as its PURPLE machine. So rapidly was the workload 
expanding, however, that this diminution of its responsibility did not 
prevent the cryptologic branch from bursting the seams of its Navy 
Department building offices. In 1942, it moved into the brick buildings of 
a former girls' school at 3801 Nebraska Avenue, at the corner of 
Massachusetts Avenue, in a quiet section of northwest Washington. In 
the fall of 1941, about 700 persons, including 80 officers, had been doing 
communications intelligence in the entire Navy; two thirds of them were 
intercepting, direction-finding, or training for that work; the others, 
including most of the officers, were solv- 
ing and translating. By the end of the war, there were 6,000. 
The Army's growth was even more spectacular. It multiplied its 
communications-intelligence manpower thirty- fold from its strength 
December 7, 1941, of 331—44 officers and 137 enlisted men and 
civilians in Washington, and 150 officers and men in the field. Ever-
growing requirements quickly dwarfed early estimates, such as the one 
early in 1942 that a staff of 460 would suffice, and kept up a relentless 
pressure for more and still more workers. Yet the agency faced stiff 
competition for them in manpower-short Washington. Moreover, the 
necessity for employees to be of unquestionable loyalty and 
trustworthiness, because of the sensitive nature of cryptanalytic results, 
and the importance of their being temperamentally suited to the highly 
specialized nature of the work, greatly reduced the number of prospects. 
To fill its needs, the agency launched a series of vigorous but discreet 
recruiting drives . It snatched people out of its school even though they 
were only partially trained: during the school's entire time at Fort 
Monmouth, New Jersey, not one student completed the full 48-week 
course. It brought in members of the Women's Army Corps—almost 
1,500 of them. These measures enabled the agency to grow to a strength 
of 10,609 at its peak on June 1, 1945—5,565 civilians, 4,428 enlisted 
men and W.A.C.'s and 796 officers. (This figure excludes cryptologic 
personnel serving under theater commanders overseas.) Nevertheless, 
the personnel supply never caught up to the demand. In April, 1944, for 
example, the agency had more than 1,000 civilian positions empty. 
But its growth soon made more space necessary. Like the Navy, it 
found a former girls' school ideal for its purposes. During the summer of 
1942, it moved from the Munitions Building to Arlington Hall, whose 
brick buildings stood on 58 wooded acres fronting on Glebe Road in 
Arlington, Virginia, about three miles from downtown Washington and 
away from the eyes of enemy agents. The agency soon outgrew even this, 
and in the late fall of 1942 began expanding into Vint Hill Farms, an old 
estate in the Virginia horse country about 50 miles from Washington. 
Giant intercepting towers and half a dozen ugly barracks-like buildings 
soon disfigured the lovely Blue Ridge foothills, and here, in rooms filled 
with desks with tilted tops, 
most of the Army's traffic analysis was done. In addition, the agency 
taught most of its cryptology here, with the removal of its school from 
Fort Monmouth in October, 1942. 
In June of 1942, owing to a reorganization in the Office of the Chief 
Signal Officer, the outfit shed its old name of Signal Intelligence Service 
and gained and lost three new ones within two months. Then from July, 
1942, to July, 1943, it was called the Signal Security Service, and from 
July, 1943, to the end of the war, the Signal Security Agency. Lieutenant 
Colonel Rex Minckler, chief since before Pearl Harbor, was replaced in 
April, 1942, by Lieutenant Colonel Frank W. Bullock. In February, 1943, 
Lieutenant Colonel W. Preston (Red) Corderman, tall, husky , quiet, 
pleasant, who had studied and then taught in the S.I.S. school in the 
1930s, became chief. He remained in the post to the end of the war, 
rising to a brigadier general in June, 1945. 
Its population explosion and its voluminous output strained its 
administrative structure, and this was realigned several times. As of 
Pearl Harbor it was divided into four sections: the A, or administrative; 
the B, or cryptanalytic; the c, or cryptographic, and the D, or laboratory. 
The c, or cryptographic section, devised hundreds of codes and 
ciphers during the war and produced thousands of key lists. It printed 
5,000,000 classified documents, some running to many pages each, and 
distributed them in a carefully guarded manner throughout the world, 
accounting for each one. It tested the security of Army cipher machines 
(mainly Friedman's M-134 SIGABA) by attempting to solve them—and 
found that they generally proved impregnable. It supervised the 
mechanization of Army cryptography—the increasing replacement of 
strip cipher and M-209s and similar slow systems with typewriter-
keyboard cipher machines, often with an on-line capacity . Only such 
mechanization enabled Army cryptographers to keep up with the ever-
rising flood of traffic: the 23,000 codegroups a day that the 5th Army 
headquarters processed during its Sicily campaign strained even the 
machines to their limit—and by the time that army was marching on 
Rome, its headquarters was handling 40,000 groups a day. Traffic 
volume passed belief: in Hollandia, a million groups a day in November, 
1944; at the Army's European Theater of Operations headquarters even 
before OVERLORD, 
1,500,000 to 2,000,000 groups a day, or the equivalent of a shelf of 
20 average books. The biggest message center of all, the War 
Department's in Washington, handled its peak load on August 8, 1945: 
nearly 9,500,000 words, the equivalent of almost one-tenth the total of 
French intercepts in all of World War I. 
In August of 1942, subsection 6 (traffic) of the crypt-analytic section 
was upgraded to an E, or communications, section, to disseminate the 
solutions and to send directives to the field intercept units. In December, 
the shop of the cryptographic section was set up as the nucleus of the F, 
or development, section, for cryptographic equipment. In March of 1943, 
all six sections were elevated to branches, and by the following year two 
more had been added: the machine and the information and liaison 
branches. The Army had begun to use machines for cryptology in 1936, 
when Hollerith tabulating machines facilitated the compiling of codes. 
Their cryptanalytic potential had also been noted in that same year. By 
Pearl Harbor, 13 I.B.M. machines tended by 21 operators were working 
on S.I.S. projects. The personnel-short agency converted as many tasks 
as possible to mechanical operation, and the o, or machine, branch grew 
to enormous proportions. The 407 machines and 1,275 operators that it 
had by the spring of 1945 handled accounting and cryptologic tasks that 
would otherwise have required the hand labor of impossible numbers of 
clerks. 
The cryptanalytic branch, then headed by Solomon Kull-back, one of 
the three original cryptanalysts hired by Friedman in 1930, was much 
the largest, with 2,574 people in July of 1944, 82 per cent working on 
Japanese Army messages. To balance the agency and reduce the number 
of branch chiefs reporting to its commanding officer, the agency was 
reorganized the following month into four divisions: intelligence, which 
did traffic analysis and crypt-analysis; security, which handled 
cryptography and radio countermeasures and formulated and executed 
policy and technical doctrines; operating services, which provided 
services for the intelligence and security divisions and ran the secret-ink 
laboratory; and personnel and training. 
Though this set-up held until the war ended, operational control of 
the agency passed on December 15, 1944, to c-2, the military intelligence 
section of the War Department General Staff, which was the agency's 
major customer and 
which, as such, for many months had indirectly guided its activities. 
The Signal Corps merely retained administrative control. This confusing 
arrangement—complicated further by the agency's having both staff and 
command functions— ended in August, 1945, when the War Department 
transferred all signal intelligence units to agency control. On September 
6, four days after the war ended, the War Department ordered the 
creation within G-2 of a new cryptologic organization by merging the 
Signal Security Agency, the field cryptanalytic units, and Signal Corps 
cryptography. This was the Army Security Agency, which came into 
existence September 15, 1945. 
Throughout the war, most of the intercept material for Signal Security 
Agency headquarters was supplied by the 2nd Signal Service Battalion. It 
had been created as the 2nd Signal Service Company on January 1, 
1939, by Major General Joseph Mauborgne, the chief signal officer, out of 
the 1st Radio Intelligence Company at Fort Monmouth, plus the radio 
intelligence detachments of signal companies in the Canal Zone, Fort 
Sam Houston, Texas, the Presidio, San Francisco, Fort Shafter, Hawaii 
and Fort McKinley, Philippine Islands. Commanding its 101 enlisted men 
was First Lieutenant Earle F. Cooke. It grew rapidly—in October, 1939, a 
detachment under First Lieutenant Robert E. Schukraft arrived at Fort 
Hunt, Virginia, to install and operate a new Army intercept station. With 
the onset of war, the imperative demands for manpower compelled the 
Army, on April 2, 1942, to increase the company to battalion strength. 
Eventually it expanded to an enormously oversized company of 5,000 
men. From April, 1942, to the end of the war, its commanding officer was 
the Signal Security Agency chief. When G-2 took operational control, the 
battalion was redesignated the 9420th Technical Service Unit, which at 
the end of the war became part of the Army Security Agency. By that 
time, the original four radio circuits on which it was sending intercept 
material back to Washington at the time of Pearl Harbor had swollen to 
46 full-time radioteletypewriter channels. 
The Army, like the Navy, established cryptanalytic units in the several 
theaters of war. Their organization varied from one theater to another. 
The South West Pacific Area, Under MacArthur, had at its headquarters 
a communications-intelligence unit called the Central Bureau and in the 
field a number of subordinate units. Central Bureau, or 
I    ' 
l^ll 
simply C.B., had been founded in August of 1942 by Lieutenant 
Colonel Joe R. Sherr, who had been head of the 18-man 2nd Signal 
Service Company detachment in the Philippines and who had 
accompanied MacArthur to Australia. Later, Abraham Sinkov, who had 
been another of Friedman's original cryptanalysts, went out to take 
charge. C.B. was quartered in a rambling wooden house—which local 
legend said was a former whorehouse—close to the Ascot racetrack in 
Brisbane. A guard stood in front. A small air-conditioned brick building 
at the track itself housed the I.B.M. machinery. Sinkov worked -wonders: 
when a downed Japanese bomber yielded an air-to-ground codebook, it 
was discovered that Sinkov had already recovered nearly all of it. His title 
at the end of the war was Cryptanalytic Officer, Signal Intelligence 
Service, U.S. Army Forces, Far East; his rank by then was colonel. A 
sweet and unmilitary man who seemed slightly embarrassed by the 
eagles on his shoulders, he was unable to return a salute without 
blurting out a "Good morning." He was awarded a Legion of Merit and an 
Oak Leaf Cluster to it for his work. 
Some elements of the Central Bureau were—despite the name—
attached to widely scattered units. MacArthur's chief signal officer, 
Brigadier General Spencer B. Akin, who enjoyed more authority than any 
other theater signal officer, attached communications-intelligence units 
to major headquarters so that the intelligence would be promptly 
available to officers who could act upon it. He even assigned one such 
detachment to Admiral William F. Halsey, Jr.'s flagship, while Admiral 
Spruance found the Army service so valuable, when he took command of 
the 5th Fleet, that he kept the communications-intelligence specialists 
with him. 
In addition, Signal Corps radio intelligence companies provided 
tactical, combat-level communications intelligence, One of the first, the 
101st Signal Company (Radio Intelligence), replaced Hawaii's old Monitor 
Post 5 in July of 1942, vastly improving the quantity and quality of the 
work. Typical, perhaps, of these companies was the 138th. Trained in 
Spokane for Europe and then transported to the East Coast, it was 
loaded aboard a transport and promptly shipped through the Panama 
Canal to Australia, landing there in June of 1943. The 299-man 
company was mobile and self-contained so that it could operate in 
isolation: it 
was mountable within two hours and had its own truck-drivers, 
cooks, repairmen, and so forth. The men lived in tents. 
The company's mission was to determine the Japanese order of battle 
and ascertain military concentrations and movements. Most of its work 
involved air-to-ground messages. To pick up these low-power 
transmissions, it had to move forward from island to island as the Allies 
advanced. Its first position, early in 1944, was at Nadzab, an airstrip in 
the Markham Valley of New Guinea. One subordinate direction-finding 
group was over a hump at Gusap; another was on an abandoned ranch 
near Darwin, Australia, where it enjoyed fresh meat daily. In the middle 
of the year it advanced to Biak , a small island north of New Guinea, 
where it was nearly strangled by the thick jungle, and it went ashore on 
Leyte about five days after the first wave of invasion troops. By then its 
direction-finding groups were scattered all over the South Pacific. 
The unit worked near the front lines so as to get as many intercepts 
as possible. So close were they that on Leyte late in 1944 Japanese 
paratroops dropped on the unit, apparently having mistaken it for a 
command post because of its numerous antennae. One startled 
radioman, isolated in a direction-finding booth in the middle of a 
clearing, suddenly heard bullets whizzing all around him. The 
codebreakers dropped their pencils, grabbed their rifles, and engaged in 
rather more direct action against the enemy than that to which they were 
accustomed. The paratroopers were driven off, but not quickly enough to 
save the unit's documents from the flames. 
Its radio operators, specially trained in Japanese Morse, listened in 24 
hours a day on at least some of its two dozen receivers. Sometimes just 
the circuits being used would give Japanese intentions away. On Biak in 
1944, the unit quickly learned that messages on a certain frequency 
invariably preceded an evening air raid—a bit of foreknowledge that 
enabled one member to collect regularly on sure-fire bets with a sergeant 
from a nearby outfit. Other times the 20-odd nisei in the unit intercepted 
Japanese cleartext. Usually, however, the radiomen typed out the coded 
intercepts and handed them to a traffic analyst. Most of the messages 
reported planes flying from one point to another, and the analyst, by a 
study of call-signs, could tell which unit and which points were meant. 
The 15 
cryptanalysts had the mechanical task of stripping the additive from 
codes that had been solved at C.B. Each day a report summing up the 
unit's conclusions went rearward to 5th Air Force headquarters, to which 
the unit had been attached, switching from the Signal Corps under C.B. 
to the Army Ah* Corps and receiving the new name of 1st Radio 
Squadron, Mobile. 
Success usually came in the humble form of an early warning of an 
air raid that probably saved American lives, or as some insight into a 
Japanese move that enabled an American commander to neutralize it. 
Late in the war, the unit's solution of Japanese meteorological codes told 
American bombing commands what they wanted to know most —weather 
conditions over target. The outfit alerted the Allies to a major Japanese 
build-up when it solved a message reporting the presence in an airplane 
of two high-ranking officers of Japan's 4th Air Army, which up to that 
time had been thought to be in northern China. But its greatest feat was 
the discovery of a huge concentration of Japanese air strength in 
Hollandia. The 5th Air Force launched massive raids and destroyed more 
than 100 enemy planes. Consequently they were not present to attack 
the American invaders, who splashed ashore with virtually no opposition. 
 
The Imperial Japanese Navy had commenced its crypt-analytic efforts 
in 1925 with the creation of an ultra-secret Tokumu Han ("Special 
Section") in the 4th, or communications, Department of the Naval 
General Staff. It then numbered six persons, including clerks, and was 
located in the red brick Navy Ministry building in Tokyo. Among its early 
members were the young naval officer Hideya Morikawa, nephew of Chief 
of Staff Admiral Kanji Kato , and Morikawa's former superior, First 
Lieutenant Kamisugi, who had handled cryptography aboard the flagship 
Nagato. Captain Kowalefsky, the Polish cryptologist who had improved 
the codes that Yardley had solved, lectured on cryptanalysis, and the 
neophyte codebreakers cut their eyeteeth on the GRAY code of the U.S. 
Department of State, making their entry through the classic technique of 
identifying NADED as period.* 
*Whether this solution was made in cooperation or in competition 
with the Ango Kenkyu Han, the Foreign Ministry's cryptanalytic section, 
is not known. 
They also solved Chinese cryptograms during the Manchuria incident, 
primarily because these were based on a commercial codebook that 
transformed the Chinese ideographs to four-digit numbers for telegraphic 
communication. After the Japanese seizure of Shanghai early in 1932, 
Morikawa was sent there as chief of a cryptanalytic unit attached to the 
3rd Fleet. He solved a Chinese message that corroborated a slightly 
doubtful Tokumu Han solution of an American GRAY message reporting 
Chinese plans to use its Air Force to attack Japanese troops. Instead the 
Japanese struck first, catching most of Chiang Kai-shek's Air Force at 
Hangchow. 
The Tokumu Han failed, however, to break two-part codes, such as 
the State Department's BROWN code, those used by the American Navy, 
and those introduced by Yardley into Chinese communications when he 
was Chiang's cryptologist—except in extraordinarily favorable 
circumstances. One such occurred on February 26, 1936, when two 
regiments mutinied in Tokyo and several statesmen were assassinated in 
an attempted coup d'etat. This furnished the cryptanalysts with an ocean 
of text and plenty of probable words to go fishing with. For a short time 
they read most American communications, including those of the naval 
attache. Then the United States changed systems, and the skill of the 
Tokumu Han again proved unequal to its task. Its resourcefulness made 
up for this: near the end of 1937, Morikawa, accompanied by a 
locksmith, a photographer, and some lookouts, broke into the American 
consulate at Kobe and photographed the BROWN code and the M-138 
cipher device, which the Japanese had never seen before. 
Soon thereafter, as part of Japan's preparation for war, the naval 
shoguns built their first big intercepting post at Owada, a village about 
fifty minutes by car from Tokyo. During American naval maneuvers, its 
direction-finding and traffic analysis helped the general staff analyze 
American forces and tactics. The Tokumu Han also added crypt-analysts, 
all of whom were officers. By Pearl Harbor there Were ten working full 
time and ten part time. They had still not succeeded, however, in reading 
American cryptograms. 
After Pearl Harbor, the rampant growth of Allied communications 
compelled the Tokumu Han to expand still further. The first batch of 
recruits—60 of them—were 
drawn form foreign-language schools and commercial colleges to 
become the first civilians in the Tokumu Han. The second batch 
consisted of about 70 reserve officer candidates selected from about 500 
in basic training on the basis of their competence in foreign languages. 
(These signal intelligence groups differed from classes learning 
cryptography.) During a five-month course at the Naval Communication 
School at Kurihama near Yokosuka— hard by the Commodore Matthew  
Perry monument—they practiced International Morse, studied the 
elementary Oriental Tenji and Tenchi ciphers as well as the Occident's 
more advanced Porta and Vigenere, and learned how to break codes and 
ciphers. Six classes, each larger than its predecessor , were trained 
during the war. Some graduates were assigned to communications 
intelligence in the intelligence units of fleet and force headquarters. In 
November of 1943, for example, the 3rd Fleet employed three officers and 
six enlisted men to monitor enemy messages. But most went straight 
into the Tokumu Han proper. 
A torrent of intercepts was pouring into it. Most came from the 
hundreds of radio receivers and direction-finders of the Owada 
Communications Unit. Some were picke up by the 20 Americans and 
Australians pressed into sei vice   with   the   Kanagawa   
Communication   Force   nea Hiyoshi, and a few messages trickled in 
from fleet radi units. Near the end of the war a unit was set up in radish 
field at Yokosuka. The entire Tokumu Han ha swollen to several 
thousand men by the end of the wai most engaged in intercepting. So 
hungry was it for competent personnel that it did something almost 
unheard-of in misogynistic Japan; it employed women—putting about 30 
nisei girls to work eavesdropping on American radiotelephone 
conversations. By the middle of 1943 it had outgrown its quarters, and 
the traffic analysis section moved to the third floor of the Naval War 
College in Tokyo, leaving only the cryptanalysts at the Navy Ministry. 
They comprised the 2nd Branch of the Tokumu Han's three. In charge 
was Captain Endo. Under him were several national sections: United 
States and Britain, with about 50 officers under Lieutenant Commander 
T. Satake; China, with about 20 officers under Lieutenant Commander 
Nakatani; Russia under Lieutenant Commander Masayoshi Funoto; and 
Italian, German, French, and others, about 10 officers. The 3rd Branch 
handled traffic analysis. It was 
J 
likewise organized on a national basis, subdivided into areas, with an 
average of two officers and a handful of enlisted men working on each 
area. This was fluid, however, and sometimes as many as ten officers 
would be working on a single area. The branch was commanded by 
Morikawa, now a captain, who, in a separate capacity, also headed the 
Owada Communications Unit. The 1st Branch planned, made policy, and 
distributed the results of the two operating branches. In charge was 
Captain Amano, with Commander Hideo Ozawa his executive officer. 
Command of the entire Tokumu Han was vested in the chief of its parent 
body, the 4th Department; in effect, this gave the Tokumu Han a seat on 
the Naval General Staff. In 1943 the head of the 4th Department was 
Rear Admiral Gonichiro Kakimoto, and at the end of the war, Rear 
Admiral Tomekichi Nomura. 
In sharp distinction to American cryptanalysts, who were reading the 
vast majority of Japanese messages, including those in the 
cryptosystems of topmost security, the code-breakers of the Tokumu Han 
failed almost completely in extracting usable information from American 
messages. They did not even attempt to solve medium- and high-echelon 
messages, couched in cryptosystems far beyond their ability. They 
concentrated instead on three simpler cryptosystems of the lowest level 
of command. Even with these, they achieved only limited success. 
Typical was their experience with a small code that they called AN 103. 
Carried by U.S. Navy patrol planes, it consisted of a few dozen 
expressions, such as enemy sighted. The code was changed every seven 
to ten days, but the same plaintext expressions appeared in successive 
editions, facilitating solution. Fortunately, such solutions were usually 
obtained too late to take any action based on them. 
The Tokumu Han cryptanalysts succeeded best with BAMS, the two-
part superenciphered Allied merchant ship code. They solved about half 
of the BAMS intercepts. How Were they suddenly able to do so well with 
so relatively difficult a system? Germany had given them the basic BAMS 
codebook, which had been captured by her raider Atlantis. Consequently, 
the Japanese had only to remove the superencipherment. BAMS provided 
occasional tidbits pf information—three transports had departed from 
Cal-tfornia, for example, or a vessel's course and speed data— out even 
here, Ozawa complained, "By the time the code 
[message] was broken, the ship was no longer in the original area." 
The Tokumu Han expended most of its cryptanalytical energies on the 
CSP 642, the strip cipher, which the U.S. Navy regarded as its lowest-
echelon system. The Navy complicated it by not using the full 
complement of 30 strips every time. Instead it eliminated from zero to five 
strips from one day to another. Thus one day's messages might use only 
25 strips, the next day's, 27, the next, 30. 
Japan had captured strip ciphers on Wake and Kiska, and with these 
she attacked the intercepts. Her methods mixed sophistication and 
naivete. To determine how many strips had been eliminated, the Tokumu 
Han used I.B.M. tabulators of the First Life and the Maiji Life Insurance  
companies of Tokyo. These took frequency counts at intervals of 30, 29, 
28, . . ., 25 and compared them; the interval that showed the most 
repetitions indicated the correct encipherment length. Many of the strip 
messages were sent by American submarines; these were identifiable by 
their indicators—BIMEC or FEMYH—and by their transmission from close to 
the Japanese coast. The Tokumu Han could know that at that position a 
merchant ship had been sunk, or that certain units of the Japanese fleet 
near there were steaming at such-and-such a course and speed, and that 
the submarine was reporting this. With this as a lead, two first 
lieutenants who had majored in English in college, Shimizu and Oda, 
composed what they thought the plaintext intercept was. They varied 
expressions, word positions, guesses of latitude and longitude until they 
had a supposed plaintext that matched the cryptogram in length and 
whose letters all differed from their ciphertexts— since in the strip 
system no letter can represent itself. Then they arranged and rearranged 
the strips until they had reproduced the ciphertext on one line and the 
presumed plaintext on another; the sequence of strips almost certainly 
represented that day's key. With it they decrypted other intercepts. 
This tortuous method—for some reason they failed to heed the 
writings of foreign cryptanalysts on solving this system—suggests why so 
little information was extracted from the strip cipher. The Tokumu Han 
kept increasing the size of the section in its American branch that 
handled strip messages until there were about 40 officers, 10 enlisted 
men, a dozen typists, two dozen women clerks, 
Professor Yamanashi of the Navy War College, and a mathematician, 
Ozaki. Though efforts were continued up to the end of the war, the life 
had long since gone out of them; the Tokumu Han, considering the strip 
cipher unbreakable for all intents and purposes, vacated its hopes for 
crypt-analysis and looked instead to traffic analysis as its chief source of 
information. 
The difficulty with this, as Lieutenant Commander Satake put it, was 
that "Our whole analysis was based on probabilities; there was nothing 
of a definite nature." The 3rd Branch graphed the volumes of urgent, 
priority, routine, and deferred messages transmitted from each major 
American station. It charted the traffic flow among the various call-signs. 
It located the transmitters by a widespread direction-finder net of a 
dozen linked stations situated from Kiska to Rabaul, from Wake to 
Manila. By following the bulge in BAMS transmissions from California to 
Hawaii to, say, Guam, the traffic analysts could predict the general area 
in which the next American assault would come. Messages from 
reconnoitering submarines or airplanes reinforced the estimate. The time 
of the attack was often gauged by noncommunications means—such as 
guesses based on previous movements—but sometimes by such 
communications intelligence as the imposition of radio silence or an 
increase in the urgency of reconnaissance messages. None of these 
methods, however, enabled the 3rd Branch to pinpoint time or place. The 
Japanese knew in advance, for example, that the United States was 
mounting an invasion of the Philippines, but when it would come they 
could tell no more closely than within a month, and upon which island 
the assault would fall, they never knew until it happened. Compared to 
the crystalline precision of America's Midway intelligence, Japanese 
intelligence floundered in a miasma of vaporous generalities. Only once 
in four years of war—at the Marshalls—did it get word to a garrison early 
enough to help it prepare for an impending attack. 
The Japanese Army, personified by the combined War and Prime 
Minister General Hideki Tojo, had panted for this war much more than 
the Navy, and so might have been expected to produce striking 
communications-intelligence results when the desired hostilities broke 
out. The woeful actuality was summed up in one sentence after the 
defeat 
 
or iNippon by Lieutenant General Seizo Arisue, chief of Army 
intelligence: "We couldn't break your codes at all." 
An incident of 1943 epitomizes Japanese incompetence in this whole 
field. It involved a future President of the United States, who, with his 
crew, formed the subject of a series of dispatches the Japanese 
apparently never solved. 
These messages were transmitted by three brave Australian 
coastwatchers, part of a widespread network whose members observed 
enemy activity from the peaks and cliffs of enemy-held islands, collected 
tidbits from native allies, and radioed their information to Allied military 
commands. They frequently gave valuable early warning of Japanese 
bombing raids and ship movements, and they assisted in the rescue of 
downed Allied airmen. 
In the early morning hours of August 2, 1943, coast-watcher 
Lieutenant Arthur Reginald Evans of the Royal Australian Naval 
Volunteer Reserve saw a pinpoint of flame on the dark waters of Blackett 
Strait from his jungle ridge on Kolombangara Island, one of the 
Solomons. He did not know then that the Japanese destroyer Amagiri 
had rammed and sliced in half an American patrol torpedo boat, PT 109, 
Lieutenant John F. Kennedy, United States Naval Reserve, commanding. 
But at 9:30 that morning he received a 20-group message enciphered in 
Playfair, the coastwatchers' cipher system. He deciphered it with key 
ROYAL NEW ZEALAND NAVY and learned, PT boat one owe nine lost in 
action in Blackett Strait two miles SW Meresu Cove X Crew of twelve X 
Request any information X. He reported back to the coastwatcher near 
Munda, whose call-sign was PWD, that Object still floating between Meresu 
and Gizo , and at 1:12 p.m. he was told by the coastwatcher station KEN 
on Guadalcanal that there was a possibility of survivors landing either 
Vangavanga or islands. 
This was just what Kennedy and his crew had done. They had swum 
to Plum Pudding Island, one of a group that hangs from the southeastern 
tip of Gizo Island. This group was behind enemy lines, and Gizo itself, 
only three or four miles away, was garrisoned by Japanese troops. 
Though messages about the missing crew continued to stream for the 
rest of the week between PWD, KEN, and GSE, as Evans called his station 
(after his wife, Gertrude Slaney Evans), the Japanese made no attempt to 
capture them. 
 
[Codebreakers 329.jpg] 
Arthur Evans' decipherment of the message of 9:30 a.m., August 2, 1943, that reported 
the sinking of John F. Kennedy's PT109 
 
Yet the importance of the crew should have been obvious to the 
Japanese from the many messages concerning it and from the search 
mission flown by P-40s, and a capture could not have caused them too 
much trouble, since on one occasion a Japanese barge chugged right 
past the island hideout of Kennedy and his crew. Even if they had been 
intercepting and reading the cryptograms, however, the Japanese may 
not have wanted to waste time looking for the Americans, since none of 
the messages specified their location. 
This excuse vanished at 9:20 a.m. Saturday morning, August 7. Two 
natives had found the sailors, who had moved to Gross Island, and had 
reported the find to Evans. He wrote a brief message: Eleven survivors PT 
boat on Gross Is X Have sent food and letter advising senior come here 
without delay X Warn  aviation of canoes crossing Ferguson RE. He drew 
up a square based on the current key of PHYSICAL EXAMINATION, 
P    H    Y    S    I 
C   A    L   E   X 
M   N   T   O   B 
D   F   G   K   Q 
R   U   V   W   Z 
 
and enciphered the message, departing from traditional Playfair only 
by leaving doubled letters unenciphered, as the s's in Gross and crossing: 
XELWA OHWUW YZMWI 
HOMNE OBTFW MSSP1 AJLUO EAONG OOFCM FEXTT CWCFZ 
YIPTF EOBHM WEMOC SAWCZ SNYNW MGXEL HEZCU FNZYL NSBTB 
DANFK OPEWM SSHBK GCWFV EK.MUE. A message of 
this length would alone suffice for the solution of a Play-fair, and 
there were four others in the same key, including one of 335 letters, 
beginning XYAWO GAOOA GPEMO HPQCW 
JPNLG RPIXL TXLOA NNYCS YXBOY MNBIN YOBTY QYNAI . . ., 
for Lieut Kennedy considers it advisable that he pilot PT boat tonight X . 
. . . 
These five messages detailed the rescue arrangements, which offered 
the Japanese a chance to get not only the shipwrecked crew but the force 
coming out to save it. All of them could have been solved within an hour 
by even a moderately experienced cryptanalyst. Yet at 10 p.m. the 
operation went off without the least hint of enemy interference. It seems 
likely that had the Japanese solved these elementary enciphered 
messages, they would have taken some action against the rescuers or the 
rescued or both. They did nothing. If their communications intelligence 
had been better, how might contemporary history have been changed! 
 
Their failure sharpens the contrast with Allied successes. For Allied 
cryptanalysts—which in the Pacific meant mostly Americans—galloped 
like Tartars through the phalanxed ranks of a legion of Japanese 
cryptosystems. They ravaged and plundered with a prodigality that did 
not trifle with petty matters. One system, when solved, proved to be used 
by direction-finding teams; though this might have afforded some 
indirect clues to Japanese attacks, it was cast aside for richer treasure. 
Commander Dyer estimated that American cryptanalysts demolished 75 
Japanese naval codes during the war. 
Among them was the four-digit code used by the marus, or Japanese 
merchant vessels—the s code. Presumably this was attacked after the 
more important combat codes had been resolved. From about 1943, it 
yielded information of the greatest value: the routes, timetables, and 
destinations of Japanese convoys. Japan's conquests consisted almost 
entirely of islands which could be supplied and reinforced only by sea, 
and Nippon itself was an island empire. 
American submarines therefore undertook in the Pacific what U-boats 
were attempting in the Atlantic, and, as with the U-boats, cryptanalysis 
helped them achieve their greatest successes.                                                                 
il 
A direct line led from FRUPAC to the office of Captain R. G. Voge, 
operations officer of the Commander, Submarines Pacific Fleet. The 
Japanese convoys radioed the positions where they estimated they would 
be as of noon on the next few days. This was to inform their own forces of 
their locations, but FRUPAC solved the messages, and Jasper Holmes, an 
ex-submariner himself, relayed them to Voge, who broadcast them to the 
American submarines. This fattened their kill. Vice Admiral Charles A. 
Lockwood, Jr., who was COMSUBPAC during most of the war, estimated 
that cryptanalytic information stepped up American sinkings by about 
one third on the trade routes to the Philippines and the Marianas. 
Eventually the submarine commanders received it so regularly that they 
complained if a convoy reached its noon position half an hour late! 
The pigboats accounted for nearly two thirds of Japanese merchant 
tonnage sunk during the war. Their torpedoing of 110 tankers from the 
East Indies resulted in oil shortages in the homeland that prevented the 
training of badly needed pilots and forced a split-up of Japan's Navy, 
with serious tactical results. Starvation at home caused Japan to make 
surrender overtures even before the islands were invaded, before the 
atom bombs exploded. After the war, Tojo said that the destruction of the 
merchant marine was one of the three factors that defeated Japan, the 
others being leapfrog strategy and fast carrier operations. This is why 
Dyer, looking back, regarded FRUPAC'S solution of the maru code as one of 
its primary contributions to victory. 
American cryptanalysts scored some long-range combat triumphs as 
well. Shortly after MacArthur invaded Leyte, they discovered from their 
reading of coded enemy messages that 40,000 soldiers were on their way 
to reinforce Japanese troops in the Philippines. American air and sea 
power met and destroyed this force, and not a man reached Leyte. 
During the Okinawa campaign, the sharp ears of the cryptanalysts 
overheard the orders that directed the superbattleship Yamato, a 72,000-
ton monster with 18-inch guns that could hurl a projectile 22 miles, to 
sortie in a last-ditch defense effort. They passed this news to the 
American commanders on the spot. Thus alerted, the com- 
manders prepared to attack her, and after a picket submarine 
reported her position, flung wave after wave of carrier-based planes at 
her. They struck her at 12:32 p.m. April 7, 1945, and after less than two 
hours of repeated bomb-hits and torpedoings, the world's largest 
battleship slid to the bottom, rumbling and exploding, and taking with 
her 2,488 officers and men of her complement of 2,767. 
FRUPAC also engendered what is probably the most spectacular single 
incident ever to result from crypt-analysis. 
In the spring of 1943, Admiral Isoroku Yamamoto came down to 
Rabaul to take personal charge of the deteriorating situation in the 
Solomon Islands. Japan had just been pushed off Guadalcanal and her 
supply lines were being snarled by Allied air attacks. Yamamoto welded 
together the biggest Japanese air armada of the war and sent it against 
the Allies, achieving some tactical successes. In preparation for further 
aerial offensives, the stocky, black-browed seaman decided to make a 
one-day morale and inspection tour of bases in the upper Solomons. 
Those bases would have to be alerted, together with several other units, 
so that they could make the many preparations needed for an inspection 
by the Commander in Chief Combined Fleet. At 5:55 p.m. on April 13, 
1943, the commander of the 8th Fleet broadcast Yamamoto's itinerary of 
five days hence to the 1st Base Force, the 26th Air Flotilla, all 
commanding officers of the llth Air Flotilla, the commander of the 958th 
Air Unit, and the chief of the Ballale Defense Unit. The great variety of 
addressees, plus the need to safeguard the person of the head of the 
Navy, makes it almost certain that the Japanese communicator selected 
the current edition of JN25—the most widely distributed high-security 
code—in which to armor this information. 
Unfortunately for the Japanese, this armor plating had been dissolved 
in the acid of Allied cryptanalysis. As with the pre-Midway solution, the 
scattered codebreaking units had exchanged their results—possibly 
augmenting them this time with documents salvaged a few weeks 
previously from the grounded submarine 1-1. Though the additive had 
been changed only two weeks before, on April 1, large portions of it had 
been recovered. At FRUPAC, these results had been punched onto cards 
for the I.B.M. machines. FRUPAC'S monitors had intercepted the messages 
that the 8th Fleet commander had spread on the airwaves, and 
when this was fed to the robot cryptanalyst in a form palatable to it, it 
swallowed it, digested it to the accompaniment of horrendous clickings 
and rattlings, and disgorged the Japanese plaintext. 
Because of the many addressees, the "scanners," or traffic analysts, 
had probably flagged the message as one of more than ordinary 
importance. Hence the plaintext went to a translator of more than 
ordinary competence, a 38-year-old Marine Corps lieutenant colonel, 
Alva Bryan Lasswell. He had studied Japanese as a language officer in 
Tokyo from 1935 to 1938 and had helped with communications-
intelligence activities in Hawaii since May, 1941. The message was 
essentially complete, but he helped fill in some holes, while Dyer 
recovered some additives and Wright determined the meaning of internal 
geographical codegroups: RR for Rabaul; RXZ for Ballale, a small island in 
the Solomons group, just south of Bougainville; RXE for Shortland, 
another of the Solomons, also south of Bougainville and west of Ballale; 
and RXP for Buin, a base on the southern tip of Bougainville. When this 
work was completed, Lasswell translated the message. 
 
The Commander in Chief Combined Fleet will inspect Ballale, 
Shortland, and Buin in accordance with the following: 
1.  0600 depart Rabaul on board medium attack plane (escorted 
by 6 fighters); 0800 arrive Ballale. Immediately depart for 
Shortland on board subchaser (1st Base Force to ready one boat), 
arriving at 0840. Depart Shortland 0945 aboard said subchaser, 
arriving Ballale at 1030. (For transportation purposes, have ready 
an assault boat at Shortland and a motor launch at Ballale.) 1100 
depart Ballale on board medium attack plane, arriving Buin at 
1110. Lunch at 1st Base Force   Headquarters   (Senior   Staff   
Officer  of   Air Flotilla 26 to be present). 1400 depart Buin aboard 
medium attack plane; arrive Rabaul at 1540. 
2.  Inspection Procedures: After being briefed on present status, 
the troops (patients at 1st Base Force Hospital) will be visited. 
However, there will be no interruptions in the routine duties of the 
day. 
3.  Uniforms will be the uniform for the day except that the 
commanding officers of the various units will be in combat attire 
with decorations. 
4. In the event of inclement weather, the tour will be postponed 
one day. 
 
Yamamoto was known to be almost compulsively punctual. He 
adhered to his schedules virtually to the split second. And Lasswell was 
now reading almost a minute-by-minute listing of his activities on a day 
during which the admiral would come closer to the combat zone than he 
had probably ever done before! The cryptanalyzed intercept amounted to 
a death warrant for the highest enemy commander. 
The question was: Should it be executed? It was not an easy one to 
answer. Nimitz wrestled with the pros and cons . If Yamamoto were shot 
down, would a better man be appointed to succeed him? Commander 
Layton, the fleet intelligence officer, set out the arguments, most of which 
Nimitz well knew. 
Yamamoto, 59, was the dominant figure of the Japanese Navy. A 
prophet of air power, aggressive and determined, he devised bold, 
imaginative plans and executed them under strong leadership. He was 
the Shogi (Japanese chess) champion of his navy, and in the 1920s had 
enjoyed matching wits with Americans at poker, which he played very 
well indeed. He has lost two fingers of his right hand in battle, and he 
manipulated the cards with the remaining three in so wizardly a manner 
that he distracted his opponents. American intelligence rated him as 
"Exceptionally able, forceful, and quick-thinking." His men idolized him. 
"If, at the start of the Pacific War," wrote Commander Fuchida, leader of 
the Pearl Harbor attack, "a poll had been taken among Japanese naval 
officers to determine their choice of the man to lead them as Commander 
in Chief Combined Fleet, there is little doubt that Admiral Yamamoto 
would have been selected by an overwhelming majority." 
Layton summed up with the observation that Yamamoto was 
preeminent in all categories, that any successor would be personally and 
professionally inferior , and, finally, that the death of the Commander in 
Chief would demoralize the Japanese, who venerate their captains much 
more than Occidentals do. Nimitz concurred. He realized that the shock 
of such a leader's death, combined with the elimination of the finest 
strategist of the enemy war machine, would equal a major American 
battle victory. He was furthermore 
probably influenced by the general American hatred of Yamamoto. 
Naval officers knew that he had conceived the treacherous strike at Pearl 
Harbor that had slaughtered their shipmates and wrecked their ships. 
He had, they thought, arrogantly boasted that he would dictate peace in 
the White House.* This was why Admiral William F. ( Bull ) Halsey made 
him "No. 3 on my private list of public enemies, closely trailing Hirohito 
and Tojo." 
By chance, the Ballale-Shortland-Buin area was in Hal-sey's theater 
of operations. Consequently Nimitz sent him a top-secret command-level 
communication referring to the Yamamoto itinerary and authorizing him 
to shoot down the Japanese planes if his forces had the capability of 
doing so. Halsey was in Australia; his deputy, Vice Admiral Theodore S. 
Wilkinson, reported that he could do it, but invited Nimitz' attention to 
the danger of making the Japanese suspicious that the Allies were 
reading their codes. If they changed them, might not this deprive the 
Allies of possibly even more valuable intelligence in the future? 
Nimitz felt that this bird in the hand was well worth stay two in the 
bush . Nevertheless, he sought to minimize the danger by following 
Layton's suggestion of a cover story. This was to the effect that 
Australian coastwatchers had radioed in the Yamamoto flight 
information, probably getting it from friendly natives around Rabaul. The 
coast-watchers enjoyed a superexcellent reputation among airmen and 
so the story would ring true. If it got back to the Japanese, they might 
never even think about codes. Even if they did realize that the Allies were 
reading their codes, either by capture or by cryptanalysis, they could 
probably do no more than issue a new edition of JN25 and perhaps 
tighten cryptographic security. But this had happened before, and Allied 
cryptanalysts had broken the new codes. The most realistic assessment 
predicted that the Yamamoto mission might temporarily dim Allied 
communications intelligence while cryptanalysts sought entry into the 
new code. 
Such a loss of information is never good, but it would be less 
unfortunate now, when the Allies were resting and consolidating their 
positions, than during a major opera - 
*This was later proved to be a canard, but its authenticity was 
accepted at the time. 
tion. No such advance was planned for two and a half months. Hence 
if the Japanese changed their code immediately after Yamamoto's death, 
the cryptanalysts would have ten weeks of relative quiet to break back in. 
In his reply to Wilkinson, therefore, Nimitz ordered him to brief all 
personnel on the cover story, iterated his authorization, and added a 
personal "good luck and good hunting" to the message. 
The death warrant was now signed, sealed, and delivered. 
On the afternoon of April 17, Major John W. Mitchell and Captain 
Thomas G. Lanphier, Jr., both of the Army Air Corps, walked into a dank 
and musty Marine dugout on Henderson Field, Guadalcanal. An 
operations officer handed them a cablegram on blue tissue—the kind 
used for top-secret dispatches. It detailed Yamamoto's itinerary, 
including times of arrival and departure from each place. The airmen 
vetoed a suggestion to strafe him while crossing from Ballale to 
Shortland in the subchaser because of the difficulty of identifying the 
right craft. Instead they decided to intercept him in the air. 
Their plan depended upon Yamamoto's punctuality and required 
careful timing of its own: Ballale was near the limit of range of the twin -
engined P-38 Lightnings that the pilots flew, so there would be little fuel 
for waiting. Though the Japanese message specified arrival at Ballale at 8 
a.m. after a two-hour flight from Rabaul, calculations showed that the 
two-motored Mitsubishi ( Betty ) attack bombers would reach Ballale in an 
hour and 45 minutes; this was partially confirmed by the estimated 
hour-and-40-minute return time from the slightly closer Buin. This 
meant that Yamamoto would arrive at Ballale about 7:45 a.m. Though he 
would be escorted by six fighters, Mitchell and Lanphier decided to 
attack him about 35 miles up the Bougainville coast to avoid the planes 
that buzzed around Kahili airstrip not far from Buin. This pushed the 
time of interception back ten minutes to 7:35 a.m.—or 9:35 a.m. 
American time. 
Next morning, 18 P-38s of the 12th, 339th, and 70th Fighter 
Squadrons lifted off the Henderson runway at 7:25 (American time). 
Thirty-five minutes later and 700-odd miles away, Yamamoto's flight took 
off right on schedule. Radios silent, the Americans flew a semicircle of 
435 miles around Munda, Rendova, and Shortland at wave-top height 
to avoid radar detection. Mitchell navigated by compass and airspeed 
indicator, and two hours and nine minutes after take-off was skimming 
the waves toward the Bougainville coast. He had timed the flight to the 
split second, and suddenly, as if the entire affair had been rehearsed to 
perfection, the black specks of Yamamoto's squadron appeared five miles 
away. 
"Bogey. Ten o'clock high," called out Lieutenant Doug Canning, 
breaking radio silence. Mitchell led 14 fighters up to 20,00 feet as cover 
and to engage the fighters. Lanphier dropped his belly tanks, and, with 
his wing man, Lieutenant Rex T. Barber, climbed to within two miles of 
Yamamoto's right and a mile in front of him before his escorting Zeroes 
saw them and turned to attack. Lanphier disintegrated one of them, then 
kicked his ship on its back and looked down for the lead bomber. He 
spotted it dodging away at tree-top level. As he spun toward it, two 
Zeroes dived at him. But, he said, "I remember suddenly getting very 
stubborn about making the most of the one good shot I had coming up. I 
fired a long steady burst across the bomber's course of flight, from 
approximately right angles. The bomber's right engine , then its right 
wing, burst into flame. . . . Just as I moved into range of Yamamoto's 
bomber and its [tail] cannon, the bomber's wing tore off. The bomber 
plunged into the jungle." The Zeros screamed helplessly overhead. 
Barber, meanwhile, exploded the other Mitsubishi. Lanphier shook his 
pursuers in a speedy climb to 20,000 feet, and he and all the other 
members of the mission except one returned safely to Henderson. 
Deep in the Bougainville jungle, Yamamoto's devoted aide found his 
admiral's charred corpse still in its seat, its chin on a samurai sword. 
The body was extricated with care and solemnly burned. On May 21 a 
Japanese newscaster announced, in tones heavy with sorrow, that 
Yamamoto, "while directing general strategy on the front line in April of 
this year, engaged in combat with the enemy and met gallant death in a 
war plane." Toward the end of the communique his voice became choked, 
as if through tears . As Layton and Nimitz had foreseen, Yamamoto's 
death stunned the entire nation. On June 5, his ashes were interred with 
great pomp in Tokyo's Hibiya Park in the presence of the government and 
an immense and silent crowd. The death of the great popular hero 
disheartened 
Japanese soldiers, sailors, and civilians. "There was only one 
Yamamoto, and no one is able to replace him," said the man who 
succeeded him. "His loss is an insupportable blow to us." Cryptanalysis 
had given America the equivalent of a major victory. 
 
What happened to cryptology during World War II? 
The war worked no changes as basic as those of telegraphy, which 
revolutionized the structure of cryptography, or of radio, which ushered 
cryptanalysis into the world as a factor of importance. Rather it enlarged, 
accelerated, intensified what was already there. This held true even in 
the two most noteworthy cryptologic developments of the war. One was 
internal, in which the changes were so great as to be qualitative: the 
evolution in the operations of cryptography and the techniques of 
cryptanalysis, and one external: the elevation of cryptanalysis from just 
one among many sources of intelligence to the principal one. 
All this resulted, of course, from the immense increase in the use of 
radio. Blitzkrieg required the closest coordination between motorized 
spearheads, air support, and consolidating infantry. Global conflict 
demanded global communications. Unprecedented volumes of traffic 
streamed through radio channels. To handle it, huge agencies sprang 
into being. 
In World War I, the U.S. Army and Navy had about 400 persons in 
cryptology (excluding cipher clerks), or about one person in every 10,000 
under arms. In World War II, there were 16,000 in cryptology—40 times 
as many —and the ratio was one person in every 800. In World War I, a 
handful of officers and enlisted men in the Code Compilation Section had 
produced codes for the whole A.E.F. In World War II, hundreds of 
privates at Arlington Hall did nothing but draw up key patterns for the 
tens of thousands of M-209s all over the world which devoured a new 
pattern once every eight hours. (Eventually, a linguist on the Hall's think 
squad devised a mechanism that produced the patterns automatically.) 
In 1918, a few men had carried the packages of codebooks to the 
American headquarters that received them. In 1942, Japan was faced 
with a major logistics task in distributing new code-books to her far-
flung forces. Her disastrous pre-Midway failure to do the job in time 
showed that codes had become cargo almost as essential as food or 
ammunition. Codes and 
ciphers cloaked even more secondary forms of messages— 
meteorological, direction-finding, airplane, merchant ships'. Intercept 
stations covered the globe. Branches and subsections sprouted that the 
science had never known: the Signal Security Service had a special 
section just to distribute its solutions, another one just to improve and 
develop cryptographic mechanisms. Brass hats abounded. Recruiting 
drives were mounted. The whole paraphernalia of large organizations 
materialized. Cryptology became big business. 
At the same time, cryptology completed an evolution in the two core 
areas of cryptographic operations and crypt-analytic techniques. World 
War I had left both of them depleted and inadequate. Hand encipherment 
had barely coped with the message load, even though codes furnished a 
primitive mechanization. Brute frequency analysis had barely sufficed for 
the ADFGVX, even though it was handled by a master. The 1920s began to 
furnish the tools and ideas for which this lack cried out. In cryptography, 
Vernam, Hebern, Scherbius, Damm, and Hagelin invented practicable 
cipher machines—secure, portable, rugged, printing. Governments 
gradually introduced them into service, replacing the old pencil-and-
paper methods. In cryptanalysis, Friedman pioneered with statistical 
methods. Hill opened a window on the new vistas of mathematics. 
Cryptologic agencies hired mathematicians like Kunze and Kullback and 
Sinkov as cryptanalysts and purchased tabulating machines to make 
more calculations. Mathematics generated analytical techniques of great 
precision and power. These trends, which were still just getting under 
way in 1939, accelerated with a rush during the war and culminated by 
1945. This evolution transformed both cryptography and cryptanalysis 
and gave each a characteristic it still has. World War II mechanized 
cryptography and mathematized cryptanalysis. 
This development of cryptology's substance, like the growth of its 
administrative organization, was paralleled by the enormous 
amplification of its effects. In World War I, cryptanalysis played a central 
role in one event of high significance—the American declaration of war 
following the Zimmermann telegram disclosure. In World War II, 
cryptanalysis helped make possible at least four critical events—Midway, 
Yamamoto, the rapid cutting of Japan's lifeline, the defeat of the U-boats. 
Cryptanalysis was not 
 
 
just a tangential and merely helpful factor; it was a vital one. 
•Indeed, the higher in the politico-military realm are the events, the 
more important becomes cryptanalysis. At the front, it probably stands 
equal with prisoner-of-war intelligence or aerial reconnaisance. But 
neither of these can match it for providing insight into the strategic plans 
of top generals or the basic diplomatic policy of a whole country. A spy 
may occasionally pluck forth a richer nugget, but he cannot refine the 
quantity of ore that a cryptanalyst can, nor can he command the 
credibility. The ungrudging tributes of the two German spymasters attest  
to this superiority: Walter Schellenberg's acknowledgment that the 
assistance rendered him by the communications-intelligence chiefs 
"made most of my success in Secret Service operations possible," and 
Wilhelm Hottl's boast that his Hungarian cryptanalysts provided him 
with "at least a hundred successes such as seldom fall to the lot of a 
Secret Service working in the ordinary ways." General Ame, chief of 
Italy's Servizio Informazione Militare, listed three succinct reasons why 
intelligence chiefs like crypt-analysis : it is usually the cheapest, the 
latest, and the truest source of information. 
After the war was over, an American official familiar with the wartime 
value of codebreaking said that it had shortened World War II by a year. 
The estimate may be conservative : a Japanese victory at Midway would 
probably have cost the United States more than a year to come back. 
When asked about the value of the wartime codebreaking, Vice Admiral 
Walter S. Anderson, a former Director of Naval Intelligence, exclaimed "It 
won the war!" Hyperbole, to be sure, but indicative nevertheless. In fact, 
a letter of General Marshall, who was certainly in a position to know, 
tends to support the hyperbole. It was this vital importance of cryptology 
that was new in the world. No one could have articulated in 1919 the 
tribute that Representative Clarence B. Hancock offered at the end of 
1945 on the floor of the Congress of the United States: "I believe that our 
cryptographers [cryptanalysts] ... did as much to bring that war to a 
successful and early conclusion as any other group of men." 
For in World War II cryptology became a nation's most important 
source of secret intelligence. 
 
16 Russkaya Kriptologiya 
 
ALTHOUGH SECRET WRITING appears in Russia in the simple letter-
substitutions of 12th- and 13th-century manuscripts, akin to those of 
medieval France and Germany, political cryptography seems to have first 
come to the country under the Westernizing influence of Peter the Great. 
Among the Western innovations that he brought to the new Russia 
was the exceedingly valuable one of black chambers. Situated, like those 
of England, France, and Austria, in the post offices, they employed the 
full battery of expert openers, seal-forgers, translators, and cryptan-
alysts. At least some of the latter appear to have been German, and their 
descendants seem to have maintained a monopoly in this field for 
generations, as in the reign of Peter's daughter, Elizabeth. 
Thus the French ambassador, Marquis de la Chetardie, knew well 
that his dispatches were being opened. But they were enciphered, and, in 
the manner of diplomats everywhere, he felt safe because he thought that 
the Russians were too dumb to break his cipher. He may have been right 
about Russians, but three Germans in the black chamber were making 
mince pie out of it. He erred in writing home with a deplorable lack of 
gallantry about the Czarina, remarking that she was "given entirely to 
her pleasures" and was "so frivolous and so dissipated." The 
interceptions were seen as a matter of course by Count Aleksey 
Bestuzhev-Ryumin, grand chancellor of the imperial court. He had been 
waiting to strike back at Chetardie, who had organized a cabal against 
him because of his Anglophile tendencies. He showed the solutions to 
Elizabeth, who, blinded by her own French leanings, refused to believe 
them until he deciphered them in her presence. The next day, June 17, 
1744, as Chetardie entered his residence, he was handed a note ordering 
him to leave Russia in 24 hours. He protested; a Russian began reading 
him his dispatches. "That's enough," he said, and started to pack. 
*Russkaya Kriptologiya ("Russian Cryptology"). 
341 
At the turn of the century, cryptanalytic information was still 
informing Russian foreign policy. Foreign Minister Panin wrote on March 
26, 1800, from St. Petersburg to his ambassador in Berlin: "We possess 
the ciphers of the correspondence of the king [of Prussia] with his charge 
d'affaires here: in case you suspect [Prussian Foreign Minister Count 
Christian von] Haugwitz of bad faith, it is only necessary to get him to 
write here on the subject in question under some pretext, and as soon as 
his or his king's dispatch is deciphered, I will not fail to apprise you of its 
content." 
Twelve years later, Russian cryptanalysis played an obbligato to the 
grand symphony of the Russian winter in inflicting the first defeat on the 
hitherto unconquerable Napoleon. That military genius, though not quite 
the cryptologic moron that it has been the fashion to portray him as 
being, certainly did not fully appreciate the importance of a tough 
cryptography. He depended upon a single, easy-to-solve system during 
most of his campaigns , including the Russian; this was his petit chiffre, 
a nomenclator of about 200 groups. Even without his generals' 
predilection for partial encipherments, the Napoleonic cryptograms must 
have crumpled before the assault of the Russian cryptanalysts. How the 
solutions helped the Russians is not known, but that they must have 
been of some assistance is indicated by the fact that the victorious Czar, 
Alexander I, cited them himself when reminiscing about the war. At a 
state dinner that he gave in Paris years later for the marshals of France, 
he mentioned having read secret French dispatches. Marshal Macdonald, 
who had commanded a corps for Napoleon, recalled that one of the 
French generals had defected and said, "It is not surprising that Your 
Majesty was able to decipher them; someone gave you the key." 
Alexander denied it. "He assumed a serious air," Macdonald related, 
"placed one hand on his heart and raised the other. 'No,' he replied, 'I 
give you my word of honor.' " His cryptanalysts would have been proud of 
so stout a defense of their honor. 
 
During the nineteenth century, cryptanalysts functioned as one of the 
Czar's chief tools of despotism. Libertarian movements were growing 
increasingly restive and radical. One way in which the Okhrana, the 
notorious secret police, kept tabs on underground workers was to have 
the black 
chambers read the letters and telegrams of suspects—as well as most 
foreign mail and a random selection of the domestic post, too. 
The most popular cipher of the Russian underground seems to have 
derived from the prisons in which so many of its leaders had to serve 
time. Intercommunication among the inmates was strictly forbidden. But 
the prisoners, languishing in the tomblike solitude of their gloomy stone 
casements, with nothing to occupy their minds, had the patience, 
perseverance, and ingenuity to outwit their jailers. They knocked, using 
the number of taps to indicate the rows and columns of a simple 
checkerboard, like the original Polybius square, sometimes 6 X 6 to 
accommodate the 35 letters of the old Russian alphabet, more often five 
across and six down, with the alternate letter forms eliminated. In 
English, the checkerboard would take this form: 
 
abode f g h ij k 1 m n o p q r s t u v w x y z 
 
Thus hello would become 23 1531 31 34. Prisoners quickly memorized 
the proper numbers and "talked" at from 10 to 15 words a minute. The 
system was universal in the penal institutions of Russia, with felons as 
well as political convicts employing it. , 
One of its advantages was that it afforded communication by a great 
variety of media—anything that could be dotted, knotted, pierced, 
flashed, or indicate numerals in any way could be pressed into service. It 
often concealed a message within an innocuous handwritten letter. The 
ciphertext numbers were indicated by the number of letters written 
together; breaks in the count were indicated by minute and almost 
imperceptible spaces, much as occur naturally in many persons' 
handwriting. Spaces between Words were bridged by having the last 
letter of a word end in an upstroke if the count was to continue, in a 
downstroke if the end of the word coincided with the end °f a count. This 
subtle means, in which the cover-text bears no relation to the underlying 
message, and so does 
not have to strain to make sense, frequently bootlegged secrets in and 
out of prisons, and undoubtedly past the noses of the black chamber 
experts, until they finally caught on. 
The popular cipher that the checkerboard inspired is named for the 
Nihilists, the anarchistic opponents of the czarist regime, who may have 
invented it. The Nihilist cipher converts both the plaintext and a 
repeating keyword into numerical form via the checkerboard, and then 
adds them together to produce the ciphertext. If the keyword is ARISE, or 
11 42 24 43 15, the plaintext Bomb Winter Palace would be enciphered 
like this: 
literal plain numerical plain key 
ciphertext 
bombwinterpalace 12 34 32 12 52 24 33 44 15 42 35 11 31 11 13 15 
11 42 24 43 15 11 42 24 43 15 11 42 24 43 15 ll 
23 76 56 55 67 35 75 68 58 57 46 53 55 54 28 26 
Occasional three-digit groups will occur, as 55 -j- 54 = 109. The 
cipher is a kind of modified numerical Vigenere with additional 
weaknesses that simplify solution. It would not have baffled an expert 
very long. Yet this basic system—the adding of a key to a checkerboard 
substitution, though with important improvements—survived through 
the years to become the primary form of secret communication for 
Russian undercover agents. 
 
The Russian plan of campaign against Germany in 1914 called for an 
invasion of East Prussia by two armies. The 1st Army was to drive 
straight west into that province and grip the German defenders tightly in 
battle. The 2nd Army, to the south, was to circle around the Masurian 
Lakes, come up behind the Germans, block their retreat, and destroy 
them. This strategy naturally required careful timing and close 
collaboration between the two forces. Unfortunately, Russian 
communications were woefully inadequate. The 2nd Army had only 350 
miles of wire all told to string during its advance across the plains of 
Poland; this pitiful supply contrasts sharply with the 2,500 miles of wire 
later used in a single day by an A.E.F. army on the Western Front. At the 
same time radios were issued only to the headquarters of both armies 
and the headquarters of their immediate subordinates—their corps. 
Division and lower headquarters lacked them. The several corps 
headquarters therefore used their wire to link up with their 
divisions. Since army headquarters had exhausted their meager wire 
supplies in stringing lines to the rear commands, this left wireless as the 
only means of communication among the several corps headquarters and 
between them and their army headquarters—the two highest echelons of 
field command. 
Their messages lay naked to the enemy. The general inefficiency that 
crippled the Russian mobilization had fouled up distribution of the new 
military cipher and its keys. Within a single army (the 2nd), for instance, 
the XIII Corps did not have the key needed to read cryptograms from its 
immediate neighbor, the VI Corps. The war broke out August 4. Before a 
fortnight had passed Russian signalmen were no longer even trying to 
encipher messages, but were passing them over the radio in the clear. 
In accordance with the Russian strategy, General Pavel Rennenkampf, 
commanding the 1st, or northern, Army, began moving into East Prussia 
on August 17. The German general staff had long foreseen the two-
pronged attack—the terrain made it obvious. They had left only one army 
to defend East Prussia because their strategy called for a quick and 
decisive victory against France first. This single force was approximately 
as strong as either Russian army but desperately weaker than both 
combined, and the general staff had dictated as its strategy to strike with 
all possible strength at the first Russian force within reach, then to turn 
and attack the second. East Prussia was the homeland of the Junkers. 
The Germans preferred not to yield it to the hideous trampling of the 
Slav . 
They gave battle to Rennenkampf at Gumbinnen. Under a hammering 
Russian artillery barrage, the German troops broke and fled 15 miles to 
the rear before they could be halted. The frightened German commander 
prepared to fall back to the Vistula River and abandon East Prussia. He 
reported his intentions to the German high command, which promptly 
began looking for a replacement. But his brainy First General Staff 
Officer, Colonel Max Hoffmann, pointed out that the southern Russian 
army had already invaded so far that its left wing was actually closer to 
the Vistula than the German rear and so was in a position to cut off the 
German retreat. He convinced his chief that he had to strike against this 
wing to give the German army freedom to maneuver, if only to reach the 
safety of the 
Vistula. The Germans had somewhat mauled the Russian bear before 
their rout, and Rennenkampf, instead of pursuing to turn victory into 
triumph, had paused to lick his wounds. Hoffmann was confident that he 
would rest another day or two. He proposed, and his general agreed, to 
disengage two German corps from the front against Rennenkampf, 
switch them southward over the excellent network of German railroads, 
and fall upon the Russian southern prong with surprise. 
The movement was in its early stages when the new German 
commander, Paul von Hindenburg, and his chief of staff, Erich 
Ludendorff, who really ran the show, arrived and confirmed it. The 
difficult entrainment process began. Ludendorff flung out a screen of 
cavalry along the northern battle line to conceal the withdrawal of his 
troops and to keep Rennenkampf under observation. The division of 
forces violated the German strategic doctrine of concentration, and the 
question arose as to whether all German forces should be thrown into 
the battle against the southern force, commanded by General Aleksandr 
Samsonov. To do so would almost ensure victory, but it would also leave 
the German rear entirely unprotected from an attack by Rennenkampf. 
While the German staff was discussing the pros and cons of this move on 
the evening of August 24, a motorcyclist brought in two Russian 
intercepts. They had been forwarded on the initiative of the head of the 
radio station at the German fortress at Konigsberg. His operators, who 
had little traffic of their own to transmit, had begun listening in to the 
Russian transmissions as a diversion. 
Both messages were from the headquarters of Samsonov's XIII Corps, 
which was communicating with army headquarters by radio because 
that was the only means the corps had. And both were in the clear 
because XIII Corps had never received the proper cipher key. They 
specified exactly where the corps was going, when it expected to be there, 
and what it would do next. Was it a trick? No, because these details were 
perfectly consistent with an overall Russian directive that had been 
found in the wallet of a dead Russian officer the day before. The 
intercepts did not answer the crucial question of Rennenkampf s 
intentions. But Ludendorff decided that, with this intelligence, the 
likelihood of overwhelming victory over Samsonov was worth risking 
defeat by Rennenkampf. The orders went out 
to march the remaining troops facing Rennenkampf across the short 
inner distance between the two pincers. 
The march was getting under way next morning as Ludendorff and 
Hindenburg appeared at headquarters in Marienburg. But Ludendorff 
was not entirely free of anxiety about what he had done; second thoughts 
disturbed him. His thin line of cavalry could have been easily pierced by 
the Russian 1st Army. "Rennenkampf's formidable host hung like a 
threatening thundercloud to the northeast," he worried. "He need only 
have closed with us and we should have been beaten." Their defeat would 
have meant a tremendous moral blow to the German cause, loss of the 
country's richest grain and dairy lands, and possibly the fall of the only 
barrier between the Russian steamroller and Berlin. Should he perhaps 
have been a little more cautious? While there was yet time, should he 
leave some troops to block Rennenkampf? Or should he even call off the 
whole offensive against Samsonov and turn back against Rennenkampf? 
So much was at stake, and it rested upon little more than his soldier's 
intuition that Rennenkampf would merely crawl forward as he repaired 
his supply lines and refitted his troops. 
But at headquarters that morning there arrived what at one stroke 
lifted the burden from the minds of Ludendorff and Hoffmann and 
permitted them to prepare one of the great military triumphs of the war. 
It was a Russian intercept. It, too, was in clear, but this one was from 
Rennenkampf to his IV Corps, and it read, in part: 
 
The army will continue its attack. On August 25 it will reach the 
Wiberln-Saalau-Norkitten-Potauren-Nordenburg line; on August 26 
the Damerau-Peters- dorf -Wehlau-Allenburg-Gerdauen line. 
 
Their maps told the Germans that Rennenkampf was still moving at 
his snail's pace. The evidence of hasty German departure that the 
Russian general had seen as he advanced leisurely upon their evacuated 
positions had confirmed his erroneous opinion that the Germans were in 
full retreat after Gumbinnen. He did not want to press them too much for 
fear of forcing them to the Vistula before Samsonov could crush them. 
The Germans, however, saw at once that he could not reach any position 
in time to attack the German rear before the expected destruction of 
Sam- 
sonov was complete. Relieved, they concentrated at once on 
engineering that destruction. 
Later that morning, as the German commanders were returning to 
headquarters from a conference at a corps headquarters, they stopped at 
a railway station in Montovo for news. A signalman handed Hoffmann 
still another Russian intercept—also in clear. Samsonov had sent it to 
the cipherless XIII Corps at 6 a.m. It was a long dispatch, and 
Hindenburg and Ludendorff had already driven off when Hoffmann got it 
all. He sped after them in his own car, overtook them, and, as the two 
automobiles jounced side by side along the rutted Polish road, handed it 
over. Hindenburg stopped his car, and the officers studied it: 
 
... On 25 August the 2nd Army proceeds to the Allenstein-
Osterode line; the main strength of the army corps occupies: XIII 
Corps the Gimmendorf-Kurken line; XV Corps Nadrau-Paulsgut; 
XXIII Corps Michalken-Gr. Gardienne .... The I Corps to remain in 
District 5, to protect army's left flank .... 
 
It was, in fact, nothing less than a full roundup of the situation as 
Samsonov saw it, together with the most detailed and explicit moves to 
be followed by his army. It gave the Germans a knowledge of enemy 
intentions unprecedented in the whole of military history. It was like 
reading the mind of a chess opponent, like playing blind-man's bluff  
without the blindfold. It was almost impossible to lose. 
The Germans formulated their plans to take advantage of the 
weaknesses of the Russian dispositions. They plotted a double 
envelopment of Samsonov, and it worked to perfection. General combat 
opened the next day, the 26th. One of the German corps marching down 
from Rennen-kampf's front struck hard at Samsonov's right; during the 
night, that wing was turned. Before dawn on the 27th, a hurricane 
barrage of artillery demoralized the hungry, tired troops of his left flank, 
and before noon they had fled the field without a single serious German 
infantry assault. Soon the realization penetrated to Samsonov that 
instead of the Russians crushing a retreating German Army, that army 
had in fact almost enveloped him. His XIII and XV Corps, in the center, 
fought bravely in the confused, surging struggle, but the frantic orders 
and cries 
for help that their radios squealed in clear were all heard by the 
Germans who, fully informed, could exploit a gap here, a movement 
there. Bit by bit the Germans drove in behind the two corps from both 
sides; soon the Russians found themselves fighting both front and rear. 
By the 30th, the Germans had encircled the corps with a ring of steel 
from which only 2,000 Russians escaped. This ended the battle: there 
were no Russians left to fight. By then Samsonov was dead. He had shot 
himself in despair as he stumbled through the forest in the night of 
defeat. 
Gradually, it became clear to the Germans that they had won, as 
Hoffmann wrote, "one of the great victories in history." Almost 100,000 
Russians were taken prisoner. An estimated 30,000 were dead or 
missing. The Russian 2nd Army had ceased to exist. One of the few 
battles of the entire war that was a decisive victory, Tannenberg —as the 
Germans named it—demonstrated that the Russian steamroller was not 
quite the invincible machine that had terrorized central Europe. It 
catapulted Hindenburg to a popularity that carried him, later in the war, 
to supreme command, and, in peace, to the presidency of his country. 
Pro-German groups in Russia began to agitate for a withdrawal from the 
war. Russian morale sank. 
Hoffmann, the architect of the victory, acknowledged its real cause. 
"We had an ally that I can only talk about after it is all over—we knew all 
the enemy's plans. The Russians sent out their wireless in clear." The 
case was clear-cut. Interception of unenciphered communications had 
awarded the Germans their triumph. Tannenberg, which gave Russia the 
first push on her long slide into ruin and revolution, was the first battle 
in the history of the world to be decided by cryptologic failure. 
 
So inexhaustible were the manpower resources of Russia that not 
even a debacle like Tannenberg could cripple its war effort. "We are 
happy to make such sacrifices for our allies," replied the Grand Duke 
Nicholas, commander in chief of the Russian armies, when the French 
ambassador expressed his condolences. And even though the Germans 
turned on Rennenkampf and drove him out of East Prussia in the Battle 
of the Masurian Lakes, two Russian armies pounded the Austro-
Hungarian forces back through Lvov with such force that they retreated 
almost to Krakow. Meanwhile, though stiE plagued with shortages of all 
kinds, 
I 
gM|Ui|| 
including signal equipment, the Russians finally managed to 
distribute their cipher system to all commands by the middle of 
September. On the 14th, the Stavka, the Russian high command, 
prescribed its use for all military orders. 
The system was a numerical polyalphabetic which negated most of the 
advantages of polyalphabeticity by enciphering several letters in 
succession in a single cipher alphabet. It resembled a feeble cipher used 
by Cornwallis in the American Revolution and solved with ease by James 
Lovell. Along the top of its tableau were listed 33 letters of the Russian 
alphabet; the tableau proper consisted of eight lines of two-digit numbers 
in mixed order. Each line differed from the others, and they were 
numbered at the left in mixed order. In enciphering, these cipher 
alphabets were used in rotation, the one numbered 1 first, the one 
numbered 2 second, and so on. Each alphabet enciphered several letters 
at a time. The number of letters to be enciphered in a given alphabet 
before the next came into play lay at the whim of the encipherer, who 
informed the decipherer of this number by writing it out five times and 
then placing this group at the head of the cryptogram. If he wished to 
change this number during a message, he simply repeated the new 
encipherment group length five times, inserted it into the body of the 
cryptogram, and used that length from then on. 
Cryptograms in the Russian Army cipher thus consisted of groups of 
monoalphabetically enciphered letters, with the length of the groups 
clearly indicated by the unmistakable appearance of, say a 99999 (the 
maximum length) or a 66666. Aside from being vulnerable to the usual 
techniques of frequency analysis, the cipher would often mirror the 
telltale repeated-letter pattern of an underlying plaintext word, such as 
attack or division, that had fallen entirely within a single encipherment 
group and so had been monoalphabetically enciphered. Such a system 
does not interpose insuperable difficulties to the cryptanalyst, especially 
when, as with the Russians, it was poorly used, often with intermixture 
of plaintext. Mixed text was soon prohibited, but by then it was too late. 
For the brilliant young Captain Hermann Pokorny, head of the 
Russian subsection of the Austro-Hungarian Dechif-frierdienst, had 
cracked the system and reconstructed all its alphabets by September 19. 
His first important solution, on September 25, disclosed General 
Novikov 's lengthy 
report of his reconnaissance of Central Powers troops, with his 
additional note: "I took the decision of not crossing the Vistula." The 
message was dated 8:40 a.m.; by 4 p.m. the Austrian liaison officer had 
brought it to the attention of the German headquarters. Knowledge of 
Novikov's decision determined the initially successful Austro-German 
tactics of the battles of the Vistula and San rivers. Other intercepts were 
valuable in more local situations. A message of Prince Engalitschev, 
colonel of the 10th Russian Cavalry Division, warned of a strong attack 
on the fortress of Przemysl; the prepared commander easily warded it off 
until the Austrian advance forced the Russians to lift the siege in mid-
October. During this advance, Pokorny's group solved as many as 30 
cryptograms a day. 
It was at about that time that the Russians made their first key 
change. It apparently consisted only of altering the order in which the 
cipher alphabets were to be used, the alphabets themselves remaining 
unchanged. Solution of this would have taken Pokorny at most a few 
minutes. Any difficulty that he might have encountered evaporated when 
a Russian station repeated in the old key a message already sent in the 
new. 
Meanwhile, the Germans had, more by fortune than by foresight, 
developed a cryptanalytic service of their own. Ludwig Deubner, a 
professor of philology at the University of Konigsberg who had enlisted in 
the Landsturm as an interpreter of Russian and who was stationed at 
the Konigsberg fortress, began his radio-intelligence work by translating 
the cleartext intercepts that the fortress radio station picked up. As 
words in cipher began to appear, he undertook to solve them. Gradually 
he mastered the Russian system so that he could read messages entirely 
in cipher. At the end of September, he was called to headquarters and 
given charge of a group of interpreters who were to learn cryptanalysis. 
Soon he and Lieutenant Alexander Bauermeister—Hoffmann called them 
"quite geniuses in deciphering"—were, with their neophyte code-
breakers, sending a stream of solutions to Ludendorff each night about 
11. The chief of staff waited for them impatiently, barking, "Any 
radiograms?" at his subordinates. He based his orders for the next day in 
large measure on the intelligence the intercepts gave. When they were 
late, he would stalk into the cryptanalytic section to find out what the 
delay was. And if for a time nothing of im- 
 
portance appeared in the messages, he would growl that the intercept 
service had not been paying attention. 
Such occasions were rare. Direct telegraph connections were soon 
established between Pokorny's group and Deub-ner's; together they laid 
open virtually every Russian cryptogram that their posts intercepted. 
And they were guaranteed a good harvest when the headquarters of a 
Russian army was given permission to use radio for its front-line 
activities because its linemen were busy with repair work. 
Thus it was that the Central Powers learned from Russian wireless 
that the Grand Duke Nicholas was forming a huge phalanx of seven 
armies to rumble into the industrialized heart of Silesia in east-central, 
Europe. By the end of October, the picture of the composition, 
disposition, and strength of the Russian forces that Hindenburg and 
Ludendorff had before them could not have differed much from the 
official one at Stavka. Only the date of the advance was unknown, but 
the Germans assumed that it would take a little time before this 
ponderous Russian steamroller could get up momentum. They 
determined to seize the initiative and attack first in the hope of throwing 
a monkey wrench into the steamroller's mechanism. 
Ludendorff's plan was characteristically bold. He removed a German 
army from the defenses blocking the invader and poised it in the north 
for a plunge downwards into the right side of the Russian wedge. On 
November 11, the point of this dagger—an army under Mackensen— 
began to pierce the Russian flank. At 2:10 p.m. the next day, the chief of 
staff of one of the Russian armies under attack transmitted a long 
radiogram which the Central Powers intercepted. In addition to 
mentioning the date of the projected Russian advance, it specified the 
line of demarcation between his army and a neighbor—always a zone of 
weakness. This message lay, cryptanalyzed and translated, on the desks 
of the German headquarters for the Eastern Front at Posen by the next 
afternoon. 
It was immediately forwarded to Mackensen. At 7:30 p.m., with this 
picture of the Russian dispositions before him, he telephoned his order 
for the next day to his subordinates. It called for an all-out attack, 
concentrating on the meeting line of the two armies in the hope of driving 
them apart and breaking through. 
He achieved a massive success. The Russian forces were 
ryccmn Kpmmojiozux    353 
split; they pulled back hastily to the south. Mackensen shoved the 
dagger in up to the hilt. At the same time, Ludendorff pinned the front 
Russian armies in combat and sent a corps to turn the Russian left 
flank. He hoped to effect another Tannenberg—a double envelopment. In 
sharp fighting around Lodz, the German forces drove their enemy back, 
abetted by a constant stream of cryptanalyzed intelligence. On November 
15, for example, the German command learned that four corps were to 
reinforce Russian troops at the Ner and Bzura rivers and that another 
corps was to cross to the left bank of the Vistula at Plozk. These details 
enabled the Germans to maneuver each day as if in a war game. 
By now the Russians were changing the key to the order of the cipher 
alphabets—not the alphabets themselves— each day. The cryptanalysts 
kept pace. On November 18, it appeared that the Germans had won their 
victory when the cryptanalysts solved a message ordering a Russian 
retreat from Lodz. But the rejoicing at headquarters was cut short when 
the codebreakers read a message from Grand Duke Nicholas 
countermanding the order and directing his forces to fight on despite 
their difficult position. The flow of radio intelligence continued unabated, 
and on the 19th Mackensen even delayed giving an order until 
intercepted information was received. 
The next day a premonitory fear chilled the intercept services when 
they picked up a message from a liaison officer of the Russian 4th Army 
to a colleague, warning that the Germans had the Russian cipher key. 
The Russians had captured a German cipher key, and they apparently 
assumed that one of theirs had likewise fallen into German hands. A new 
key was instituted—and this time the entire set of cipher equivalents was 
changed. A curtain of silence descended upon the Eastern Front. 
Feverishly, Deubner and Pokorny, who was assisted by Lieutenant 
Colonel Heinrich Zemanek and Lieutenant Viktor von Marchesetti, 
grappled with the new key as the intercept posts sucked in every scrap of 
Russian wireless. The moment could not have been worse. The battle 
around Lodz raged at its peak, and just as Ludendorff was about to 
consummate his envelopment with his inferior forces but his superior 
intelligence, that intelligence was abruptly blanked out. Deprived of his 
eyes and ears, he did not know °f the Russian reinforcements that began 
to cut off the 
deeply sunk point of Mackensen's dagger. By the 21st , the point had 
been isolated, and the envelopers were themselves enveloped. A guards 
division and two cavalry corps were encircled by Russian forces with no 
apparent hope of escaping. The Russians exultantly ordered up trains to 
carry off the prisoners. 
But the next day, Pokorny's group finally subdued the new Russian 
alphabets, and the intelligence once again began streaming into German 
headquarters. Intercepts soon revealed a weak spot at Brzeziny in the 
ring of Russians. Ludendorff's headquarters radioed this information to 
the trapped commanders, who, grouping their forces densely and fighting 
hard, broke out on the 25th and reached safety, bringing with them 
10,000 prisoners. General Lietz-mann, commander of the guards 
division, won the title "Lion of Brzeziny" for the brilliant escape; the 
crypt-analysts who had showed him how best to use his fangs and claws 
purred with amusement in their secret lairs. 
This harrowing episode, resulting from a fortuitous change of key, 
balked the Germans of a decisive victory, but they had succeeded in 
throwing the vaunted Russian steamroller out of gear. Never again did it 
threaten German soil. The Central Powers pressed forward, still reading 
Russian cryptograms, and on December 6 the soldiers of the Czar 
evacuated Lodz, the second city and the industrial capital of Poland. 
Eight days later they again made a wholesale change of alphabets in 
their digit cipher. Solution again required several days, and when it was 
completed the Austro-German command learned that the Russians 
planned to dig in for the winter along the Nida River. Soon thereafter they 
gave up the old cipher altogether. 
 
When activity quickened in the spring of 1915, the Russians were 
using a simple Caesar cipher.* The multiplicity of tables used by different 
armies in the old cipher, the daily shift of keys, had evidently proved too 
difficult to handle for the half-illiterate muzhiks. The Austrian and 
German cryptanalytic organizations saw right through this transparent 
new cipher and read the indications of a projected Russian invasion of 
East and West Prussia. Then began what Colonel Max Ronge, head of 
Austro-Hungarian 
*During the Second Battle of the Masurian Lakes in February, in 
which the Russians were defeated, they used a service code called the 
RSK, which the Germans solved. Its nature is unknown. 
intelligence, called "the most brilliant period of our interception 
services." Enormous quantities of intelligence were sluiced from the 
Pokorny and Deubner groups into the offices of the operations staffs of 
the German and Austro-Hungarian commands. Helped by this, they 
parried the first tentative Russian advances, and then themselves swept 
through the whole enemy line in a rapid onslaught that penetrated 80 
miles in two weeks. 
Time after time, their solutions enabled the Central Powers to take 
steps which were so perfectly the right thing to do in each tactical 
situation that the Russian general staff was mystified by its opponents' 
apparent clairvoyance. Once the Germans fell back just two days before 
an overwhelming assault was to be launched; had they remained in 
place, their position would quickly have become critical. After the 
Germans captured Lodz, the Russians pondered the precision of the 
enemy moves and decided that the Germans must have obtained 
intelligence from air reconnaissance. 
Eventually, however, the conviction grew that the foe must be reading 
their ciphers. They did not suspect crypt-analysis. Spies, they thought, 
must have sold them to the Austrians, and in a wave of spy- mania they 
persecuted officers with German names—none of whom, Ronge said, had 
ever given anything to him. The Russians changed their cipher at the 
height of the enemy's spring offensive, but this caused the cipher clerks 
more trouble than it did the cryptanalysts, for almost all messages of 
May 15 were unintelligible to their recipients and most of those of the 
16th as well. 
The summer-long Russian retreat finally came to a halt at the end of 
September on a defensible position deep within their own territory. By 
then Russia had lost 750,000 men as prisoners and untold hundreds of 
thousands more as casualties. She simply threw more men into the war. 
She seemed to adhere to the same policy in cryptography— and with the 
same lack of success. On December 20, 1915, she put her 13th cipher 
into operation. The Austrian and German cryptanalysts recognized it at 
once as having been used elsewhere on the front, and during the 
inconclusive battles before and after New Year's Day kept up with the 
enemy situation hour by hour. On June 16, 1916, the Russians began 
using their first code, a small one of about 300 groups. This development 
may have been influenced 
by the French, who had learned about the German solution of 
Russian messages from their own cryptanalyses and had passed the 
news to their allies. Or it may have resulted from Russia's own intercept 
service; just how well Russia did in military cryptanalysis is not known, 
but she did set up direction-finding stations in mid-1916 and started an 
intercept school at Nicolaieff. 
The travail of the Central Powers cryptanalysts, who were unused to 
code, was simplified when some Russian commands, who were equally 
unfamiliar with it, continued using the old system. And their work was 
made almost mechanical when the headquarters of a Russian guard 
detachment that was being joined to the 8th Army compromised the new 
system by a message in clear. A great hubbub arose in the 8th Army; a 
new code was instituted; this one cryptanalysts solved without much 
trouble. By then they were reading up to 70 Russian dispatches a day. 
The German solutions seem to have been made in the radio stations of 
the various fortresses, to which Deubner communicated the keys as he 
solved them. Some of the Austrian cryptanalysis was done at Ronge's 
Austro-Nord Penkala under the command of Captain Karl Boldeskul. 
Later in the war, when Pokorny was promoted to head of the whole 
Kriegschiffregruppe, the Russian subsection of the Dechiffrierdietist at 
headquarters was taken over by von Marchesetti; in 1918 Rudolf 
Lippmann succeeded him. 
On November 6, 1916, the Russian Army of the Danube suppressed 
the radio use of cipher No. 14 as known to the enemy, and on December 
17 another cipher was called out of service because the radio station of 
the 1st Cossack Division had been captured. Four days later they 
returned to the air with a code that proved to be merely a slightly shifted 
version of one that had been instituted a week earlier. All these changes 
the cryptanalysts followed with contemptuous ease. The increasing 
disorganization of the Russian armies contaminated the radio services, 
and as discipline relaxed, garrulity increased. One day early in 1917, the 
Dechiffrierdienst solved 333 radiograms, from which it inferred that the 
Russian secret communications were rapidly disintegrating. In March the 
Czar-was overthrown, in July an all-out offensive by the Russian armies 
collapsed, and in October the Bolsheviks, using the people's 
overwhelming desire for peace, seized power and took Russia out of the 
war. 
The way to this situation was opened primarily by Russia's military 
failure. While this resulted largely from the lack of munitions, food, and 
supplies that the underin-dustrialized country could not supply, the 
tactical defeats inflicted by the Central Powers obviously played a 
conclusive role. And these victories of a David over a Goliath, though 
aided by superior German equipment, discipline, and logistics, were 
mainly engendered by cryptanalysis. 
"We were always warned by the wireless messages of the Russian staff 
of the positions where troops were being concentrated for any new 
undertaking," wrote Hoffmann. So complete was the intelligence that he 
could say: "Only once during the whole war were we taken by surprise on 
the Eastern Front by a Russian attack—it was on the Aa in the winter of 
1916—17." This dramatically underlines the importance of cryptanalysis 
in the outcome of the war in the East and in all that that entailed. 
Indeed, it may not be too much to claim that the establishment of 
Communist power, perhaps the supreme fact of contemporary history, 
was made possible to a significant degree by the cryptanalysis of czarist 
secret communications. 
 
The consolidation of the Soviet regime permitted Lenin and his 
colleagues to turn not only to the difficult problems of running the 
world's first socialist state but also to the traditional Communist activity 
of fomenting class struggle and the revolution of the proletariat. They felt 
justified in using subversion as well as the more orthodox methods of 
propaganda and political agitation in advancing Marxism in countries 
that had not yet reached Russia's stage of historical development. 
It was during the Spanish Civil War, in which Russia actively aided 
the Loyalists, that a cryptographic element that had served the 
revolutionary predecessors of Lenin & Co. reappeared in a form both 
streamlined and more secure. This was the straddling checkerboard. Its 
straddling feature makes use of cipher equivalents of two different 
lengths—lengths usually of one digit and two digits; the two sets of 
equivalents are so constructed that the cryptographer can 
unambiguously separate them when they are run together. The 
cryptanalyst, however, not knowing which digits are singletons and 
which form,pairs, may divide the ciphertext incorrectly, thereby 
"straddling" many of the true pairs and combining two singletons into a 
false 
 
pair. The device also reduces the length of the numerical text as 
compared with checkerboards in which all letters are replaced by 
numerical pairs. Straddling was first employed by the Argentis in some of 
their 16th-century papal ciphers (one wonders whether the atheistic 
Communists knew!). 
The straddling checkerboard produces single-digit equivalents by 
leaving the side coordinate off one of the rows of the checkerboard. A 
letter in this row is enciphered by just the single coordinate above it. If 
ambiguity is to be avoided, none of these singletons can start a two-digit 
group. Hence none caa be used as a side coordinate (which is read first). 
Using eight digits of the ten as singletons leaves two digits as side 
coordinates;, each of these two side coordinates can then pair with the 
ten top coordinates (the singletons may serve in second position) to 
produce 20 two-digit groups. This configuration makes 28 ciphertext 
equivalents available for plaintext elements. 
It was used in 1937 with keyword M DEL VAYO, the M the initial of 
the agent, the DEL VAYO the name of a Spanish Communist. The two 
extra spaces were used for a period and a letter-number shift sign: 
 
0987654321 
mdel v a y 6 bcf ghuj knp qrstuwxz. / 
 
With this, e = 8, a = 5, b = 10, t = 27, and so on. There will be no 
single 2 or 1. The decipherer takes all 1's and 2's as the first digits of a 
two-digit group, and joins to it whatever digit follows. He takes any digits 
from 3 to 0 as individuals if they are not already part of a pair. Thus the 
ciphertext 828115125 can be unambiguously divided as828115125 and 
deciphered to Espana. 
Other configurations are possible. Seven single digits will permit three 
side coordinates, for a total of 37 cells in the checkerboard. Six 
singletons will produce 46 cells; five, 55, and so on down to one 
singleton, 91 cells. The arrangement with 28 equivalents has been widely 
used for Latin-alphabet texts, that with 37 for Cyrillic texts. 
Although the M DEL VAYO checkboard was used by the Swedish 
fellow traveler Dr. Per Meurling only to teach his fiancee secret writing, 
his knowledge of it testifies to 
its use at that time by the Communists. He subjected the numerical 
text resulting from the checkerboard to a multiplication, and then 
reconverted the product to letters in another checkerboard. The system 
resembled but was much weaker than Pliny Earle Chase's of 1859, and it 
is unlikely that the Russians would have used it in that form. 
The Spanish Civil War, a prelude to World War II, furnished the 
Fascist-Nazi and the Communist dictatorships with a testing ground for 
the weapons they would use in the later conflict. Perhaps this extended—
for the Communists,, at least—to the cryptologic arena as well. Red 
ciphers of World War II had purged themselves of whatever weaknesses 
were discovered in Spain and had erected upon their strengths an 
impregnable structure. 
 
Any suspicious letters were turned over to the chief cryptologic agency 
of the Soviet Union, the quasi-independent Spets -Otdel ("Special 
Department"), whose primary task was reading the coded messages of 
other nations. Though attached to the foreign directorate of the secret 
police, it was actually responsible to the Central Committee of the 
Russian Communist party, the Soviet 
.. Union's real ruling body, whose chairman was first Lenin and then 
Stalin. In 1938, it appears to have been renamed and reorganized into 
the 5th Directorate of what was then the N.K.V.D. 
Up until that time, and beginning, apparently, around 1927, its chief 
was Gleb I. Boki, an old Bolshevik and friend of Lenin, who, at the same 
time, sat on the Supreme Court of the Soviet Union! Born in 1879, he 
had taken part in prerevolutionary activities and had gained the 
Communist badge of honor by being arrested many times and winning a 
three-year sentence in Siberia . At the time of the Revolution, he was 
secretary of the Bolshevik cell in the capital, St. Petersburg. In the early 
1920's, he headed the Cheka in Turkestan, where he so terrorized the 
country that legends about him remained alive long after he had gone: 
that he ate dog meat (especially execrable to the Moslem population), 
even that he drank human 
, blood. It seems true, however, that as head of the Spets-Otdel Boki 
held wild parties, if not actual orgies, with a group of carefully selected 
guests at his rented dacha near Batumi during his vacations. He kept his 
office door always 
i   closed and used a peephole with one-way glass to examine 
visitors. Tall and stooped, with a sinister expression and cold blue 
eyes that gave one the impression that he hated the very sight of you, he 
gave at least one girl worker the shivers whenever he emerged from his 
sanctum and spoke to her when she was alone in the office on night 
duty. Never with a hat and always with his raincoat, which he wore in all 
seasons, Boki seems to have been an administrator rather than a 
cryptologist. He was executed in 1938 in the great Stalinist purges. 
Afterwards, it was discovered that he had, most unsocialistically, 
hoarded gold and silver coins. 
The Spets-Otdel handled both cryptography and crypt-analysis. In 
1933, the cryptographers worked in a big room on the fourth floor of a 
former insurance building that the O.G.P.U. occupied at 6 Lubyanka 
Street. The cryptanalysts were then on the top floor of a former Ministry 
of Foreign Affairs building at the corner of Lubyanka Street and 
Kuznetsky Bridge Street. The comings and goings of ordinary tenants on 
the lower floors and of the members of a diplomats' club disguised the 
presence of the office. In 1935, both cryptographers and cryptanalysts 
moved into the new building of what was now the N.K.V.D. at 2 
Dzerzhinsky Street (named for the first head of the secret police, Felix 
Dzerzhinsky). 
The cryptographic division was subdivided into several sections. There 
were separate sections, for example, for the N.K.V.D. network inside 
Russia, for the border patrols (under N.K.V.D. jurisdiction) and 
uniformed N.K.V.D. troops, for Gulag , the prison administration, for 
clandestine agents abroad, and for the "legal" N.K.V.D. residents abroad. 
This last section was No. 6. Its chief, Koslov, was dismissed during the 
purges, and after his successor was sent to the United States as a cipher 
clerk, the section was headed by a man not unknown to later fame— 
Vladimir M. Petrov, who defected in 1954 and was granted asylum in 
Australia,* 
*Petrov named three men who were his bosses at different times while 
he was section chief— Ilyin , Degtjarov, and Shevelev. Whether these were 
the heads of the entire, then newly formed N.K.V.D. 5th Directorate, or 
whether they were department heads (a possible administrative level 
between the section chiefs and the directorate's chief), is not known. The 
former may be more likely in view of the fact that Boki's successor, 
Shapiro , lasted only a month or two before he was arrested, and three or 
four of Shapiro's successors were also arrested. 
The growth of Section 6 may measure that of Soviet espionage. When 
Petrov joined in 1933, there were only 12 workers; in 1951, there were 45 
or 50. As cipher clerks in the N.K.V.D., entrusted with the deepest 
secrets of the most secret agency in Russia, these people were among the 
elite of the Soviet Union, yet their jobs in this workers' paradise were 
anything but heavenly. Ciphering was done by hand, and early in his 
career Petrov often worked until midnight to clear up the day's backlog of 
telegrams. Later, as deputy section chief, Petrov did no actual 
enciphering or deciphering, but read the telegrams, corrected them, and 
signed them. 
The cryptanalysts were divided into geographical and linguistic 
subsections—Chinese, Anglo-American, and so on.* The future Mrs. 
Ekdovia Petrov, who had studied Japanese for two years at a language 
school in Moscow, was assigned to the Japanese section. Among her co-
workers were Vera Plotnikova, daughter of a professor of Japanese and a 
long-time resident of Japan; Galina Pod-palova, who liked things 
Japanese so much that she wore kimonos at home; Ivan Kalinin , who 
came in occasionally as a consultant; and Professor Shungsky, old, 
distinguished, vigorous, the section's supreme authority on Japanese. He 
gave Doosia (the future Mrs. Petrov's nickname) an affectionate kiss on 
the cheek when, after four years of his tutoring, she translated a difficult 
sentence to his liking at her final examination. 
Shungsky had served in the czarist Army, and many others in the 
cryptanalytic section were elderly former Russian aristocrats, including 
counts and barons. This shocking breach of Bolshevik polity resulted 
from a serious shortage of linguists, who were needed in codebreaking. 
Cryptanalysts themselves were so excessively scarce that even when they 
were jailed they continued to work. Vladimir Krivosh, the father of 
Doosia's first love and de facto  
*In 1933, it also had a military intelligence group, headed by a 
Colonel Kharkevich, a solid, impressive man who reported to both Boki 
and the general staff. This group appears to have later been abolished or 
transferred to the Army; Kharkevich himself was Purged in 1938. The 
head—under Boki—of the O.G.P.U. group of wyptanalysts was one 
Gusev, possibly Sergei I. Gusev, an old revolutionary, active in secret 
printing, a member of the Central Committee of the Russian Communist 
party since 1922, and on the Praesidium of the Comintern from 1930. He 
too was purged in 1938. 
husband, Roman Krivosh, had held a high post in the Okhrana; he 
was alternately arrested and released, but worked for the Spets-Otdel 
even while he was in the Butirskaya Prison in Moscow. Eventually the 
police took Roman away to the same prison, but the head of his section 
in what was then the 5th Directorate brought him his work. 
There was, of course, no security problem with inmate-cryptanalysts. 
But security was impressed on the others. They were not allowed to tell 
anyone the department in which they worked nor even where the office 
was. Doosia never even told her parents. They also had to keep out of 
restaurants, presumably because their conversations might be 
overheard. 
Did their work prosper ? It did, and very well indeed. In 1929 or 1930, 
the Spets-Otdel compiled a weekly precis of foreign telegrams that it had 
solved and sent it to O.G.P.U. department heads and to the Central 
Committee. By 1938, the pace seems to have accelerated, for by then 
Doosia had the job with a Madame Moritz of checking the typed fair 
copies that represented each day's output against their handwritten 
originals. One former O.G.P.U. official stated that the Spets-Otdel 
"carries on the work of reading codes splendidly" and praised Boki's 
staffers as "a first-class lot, often cited for emulation." 
 
The strides that the Russian Army had made in cryptography after the 
traumatic experiences of World War I were dramatized by an interchange 
of messages between incredulous Russian units at the very start of the 
Russo -German War. Moments after the Nazis launched their sneak 
attack at 3:30 a.m. June 22, 1941, a Red outpost wirelessed frantically, 
"We are being fired on. What shall we do?" Back came the stern reply, 
"You must be insane. And why is your signal not in code?" 
Red Army cryptography rested in World War II upon the enciphered 
code. The system appeared in four series: 5-digit codes for strategic 
messages, 4-digit for high-level tactical communications, perhaps of the 
rank of army headquarters, 3-digit for medium-level tactical, as of 
brigade rank, and 2-digit for the front. The Soviets replaced their tactical 
codes frequently, although sometimes a code that had been used in one 
sector of their thousand-mile front reappeared later in another. The 4-
digit codes were en- 
ciphered by 10 X 10 tables, one table for the first 2 digits and another 
for the second pair. The 5-digit codes were enciphered by additive tables 
of 300 groups changed daily. The Army and Navy shared the 5-digit 
strategic system; border patrol and N.K.V.D. units had their own 
systems, usually 4-digit. In addition, the Soviets got some Hagelin M-
209s in Lend Lease , which they apparently used as models for their own 
constructions, though it is not known where these were used. 
With enough traffic, enciphered code can of course be read. One of the 
first to do so in the case of the Russian military was the Swedish expert 
Arne Beurling. During the bitter struggle of Finland against Russian 
aggressors in the Winter War of 1939-1940, Sweden fed intelligence 
based on cryptanalysis to her neighbor. Beurling attacked the top 
system, the 5-digit strategic, which was actually a 4-digit code with an 
extra digit added as some form of check. In several of the codes, the page 
digit—the second— was repeated, so that the groups would look like 
52217, 88824, and so on. In others, the fifth digit gave the unit total of 
the preceding four digits, so that 6432 would have a check digit of 5, 
making the codegroup 64325. Beurling wrote the cryptograms on a sheet 
of graph paper with five-millimeter squares that was so large—about 3X4 
feet —that he had to order it specially. He sought to strip the 
superencipherment and, with luck, sometimes succeeded. 
Soviet strategy against Finland called for a five-pronged invasion 
along their north-south border. The middle force drove for the tiny village 
of Suomussalmi to cut Finland at her waist ; the force just north of that 
one rolled on another little village, Salla, in a secondary cut-off. But 
intelligence developed in the Swedish cryptanalytic office helped the 
Finns to repulse both Russian attacks. 
Crucial to Marshal Mannerheim 's victory at Suomussalmi was the 
information that the Russian 44th Division, a crack motorized outfit from 
Moscow, was advancing from Raate . He immediately sent reinforcements 
to Suomussalmi. Two days after his five battalions reached there, the 
Finns, dressed in white and moving like the ghosts of the north, attacked 
the Russian forces in the village, broke their resistance, and forced them 
to flee across frozen Lake Kiantajarvi. The skiing wraiths then cut off the 
retreat of the 44th Division, severed its column and destroyed it section 
by section in fighting that continued into the 
first week of 1940. Large quantities of stores were captured, but, 
Mannerheim wrote, "The enemy's casualties could not be estimated, as 
great snowdrifts over a large area covered the fallen as well as the 
wounded who were frozen to death." 
Temperatures during the battle dropped to 56 degrees below zero, and 
it was under such conditions that the Swedes solved some pitiful 
messages from isolated Russian units. One encircled group radioed that 
they were burning their papers and were going to shoot their last horse 
for food, and that this was their final message. Silence followed, and soon 
thereafter the Swedish cryptanalysts learned that the Finns had crushed 
them. Another Russian battalion sent a coded message that they were 
desperately short of supplies and would build three fires in a triangle to 
show the Red Air Force where to parachute desperately needed food and 
ammunition. The Swedes solved it and gave it to the Finns, who built a 
triangle of fires and watched with bitter satisfaction as the packages 
floated down into it. 
Swarms of Russian Air Force cryptograms were downed by the 
Swedish codebreakers. Many were orders to bomb Helsinki , and often 
these were solved before the bombers took off from airfields in Latvia and 
Estonia for the 20-minute flight to their target. Finnish authorities thus 
had ample time to sound air-raid alerts; as a result the capital suffered 
exceptionally light civilian casualties considering the number of bombs 
dropped. 
But little Finland was no match for the colossal U.S.S.R. despite her 
cryptologic advantages, and in March she signed a peace treaty. When 
the Germans invaded Russia a year later, Finland declared war against 
her harasser and later exchanged cryptographic intercepts with her new 
ally. 
German radio intelligence against the Soviet Union appears to have 
been characterized by a severe split. Strategically it enjoyed no success 
at all. The Germans did not solve the cryptosystems of the top Soviet 
military commands—primarily the 5-digit codes. Perhaps by 1941 the 
Russians had corrected their cryptographic, technique enough to keep 
the Germans from repeating the 1939 Swedish successes. Whatever the 
reason, cryptanalysis contributed little to O.K.W.'s overall picture of 
Russian strategy. 
Tactically, however, the Germans reaped rich harvests of intelligence. 
In mid-1940, when Hitler first decided to attack the Soviet Union, 
Germany had no radio-intelligence service of any kind in the East; a year 
later, when Hitler struck, the new intercept service had already provided 
him with good information on Russian order of battle. In July, a captured 
Russian Air Force captain betrayed one of the Air Force systems. This 
intelligence windfall helped the Luftwaffe destroy hundreds of Soviet 
airplanes on the ground and another hundred in a great air battle over 
Minsk . 
The resultant air superiority, plus surprise, momentum, armor, and 
speed, carried the Wehrmacht forward in a surge of victories. In 1941 
and again in 1942 Germany mounted massive offensives and overran 
vast areas of Russia. But in the winter of 1942-43, Stalingrad held and 
the German 6th Army capitulated; at the same time, Germany lifted the 
two-year siege of Leningrad . By next summer, it had become evident that 
Nazidom could not win its great victory over Bolshevism, but the troops 
hoped at least for a stalemate that would stabilize their conquests. The 
high command decided on some limited attacks to cripple Soviet 
offensive power. With the waning of Luftwaffe air mastery, Nazi 
intelligence had to depend less upon aerial reconnaissance and more 
upon wireless surveillance. In tactical operations during the Battle of the 
Dnieper in October, 1943, the chief of staff of the 48th Panzer Corps 
declared, "The best and most reliable source of intelligence was our 
Wireless Intercept Service." 
A few months later, that corps participated in one of the attacks that 
Army Group South, one of the three major German groupings on the 
Eastern Front, mounted to flatten the Kiev salient and further forestall 
Soviet offensive propensities. The 48th Panzer Corps had as its objective 
the disruption of the Russian 60th Army. Air reconnaissance produced 
no information, and the corps decided not to send out ground scouts for 
fear of alerting the Russians. The attack at 6 a.m. December 6 completely 
surprised the Russians, who recoiled in confusion. 
 
In those days [wrote the corps' chief of staff, Colonel F. W. von 
Mellenthin] we were really good at intercepting Russian wireless 
traffic; enemy messages were promptly deciphered and passed to 
Corps in time 
to act on them. We were kept well informed of Russian reactions 
to our movements, and the measures they proposed to take, and 
we modified our own plans accordingly. At first the Russians 
underestimated the importance of the German thrust. Later a few 
antitank guns were thrown into the fray. Then slowly the Russian 
Command got worried. Wireless calls became frantic. "Report at 
once where the enemy comes from. Your message is unbelievable." 
Reply: "Ask the Devil 's grandmother; how should I know where the 
enemy comes from?" (Whenever the Devil and his near relations 
are mentioned in Russian signals one can assume that a crack-up 
is at hand.) Towards noon the Russian 60th Army went off the air, 
and soon afterwards our tanks overran the army headquarters. 
 
By that evening the Germans had rolled up the Russian front for 20 
miles, and by the night of December 9 the Soviets' projected offensive 
was jolted thoroughly off balance. In the next few days additional blows 
punished them further. "The Russians were certainly flabbergasted by 
these ghost-like thrusts, which seemed to come from nowhere, and their 
wireless traffic provided abundant evidence of their bewilderment and 
anxiety," Mellenthin wrote. 
This German victory at the Battle of Radomyshl delayed but did not 
prevent the Russian offense. At Christmas, Army Group South began its 
retreat from the Ukraine . Several months later the Russians had driven 
the Germans back 650 miles from their farthest penetration. 
Mellenthin has remarked that "The Red Army of World War II was 
vastly different from the Imperial Russian Army of 1914-17, but in two 
important respects the Russians have not changed. They are still 
addicted to mass attacks, and they still show an extraordinary 
indifference to wireless security." This comment seems to hold true only 
in a tactical sense, and the adjective "extraordinary" is probably justified 
only under conditions of retreat and its accompanying confusion. 
Army Group North, for example, read 5-digit code messages very 
rarely. Of the intercepts in 2-, 3-, and 4-digit codes, it read 28.7 per 
cent—13,312 messages out of 46,342 from the beginning of May, 1943, 
to the end of May, 1944, a year in which the Russians pushed back the 
northern sector of the front slightly, though not nearly as 
ryccKUH, J\puninujiu' Petrov, E., 361 Petrov,   V.   M.,   360-361 Phelippes, T., 86-88, 417 Philippines, U.S. 
Navy crypt-analytic unit, 12, 45, 301- 
303 
Pictures, encipherment of, 203 Pierce, E. C., 279-280, 286 Pigpen cipher,  413 Placode, definition , xiv Plaintext, 
definition, xi, xv Playfair cipher,  7,   118-121, 
155, 328-330, 403 Playfair, L.,  118,  120-121 Pletts, J. St. V.,  187 Plutarch, 76 Poe, E. A., 416 Polk, F. L., 148-149 
Pokorny,   H.,   350-352,   353, 
356 
Poland, 215 
Polyalphabetic substitution, 350, 351, 353, 354 
definition, xii 
development of, 90-99 
eclipse of, 99-100 
rebirth  of, 113 
solution of,  123-124, 127- 
128,   199-200 Polybius square, 76, 121, 343, 
403 
Polygrams, definition, xiii Polygraphia libri sex, 95 Polyphonic substitution, 415 Porta, G. B., 98 
Postal Telegraph Cable Company, 203 
Praun, A., 237 
Price, B., 277, 279 
Prisoners' cipher,  343-344 
Private  Office,   109 
Probable  word   solutions, 441-442 
PROD , 390 
Prohibition,   420-422 
Protocryptography, 72 
PT-109, 328 
PURPLE,  1-2,  15, 21-26, 42, 191, 266, 273-274, 315 
Puzzle cryptograms, 411 
Qalqashandi,   80-81 
Rabelais , F., 416 
Radar, 310 
Radio, 153-165, 402 
Radio Corporaation of America,  16,  39-40, 294 
Radio intelligence, 9-10 
Radio intelligence companies, 272, 320-321 
Radio   Intelligence   Publications, 45 
Radiotelephone. See Telephone secrecy 
Random key, 199 quasi-random key, 401—402 
Raven, F. A., 26, 390 
R.C.A. See Radio Corporation of America 
RED (Japanese),  15, 22, 23 
Redman, J., 312 
Redundancy,  444-450 
Reichssicherheitshauptamt, 226-231 
Rendezvous   (film),   181-182 
Rennenkampf, P., 345-350 passim 
Ribbentrop, J. von, 216, 229 
Rickert,  E.,   171 
Rin-spuns, 77 
Riverbank Laboratories, 185- 
190 Riverbank Publications, 189- 
190, 198 
Robot cryptanalysts, 219, 236 Rochefort, J.  J.,  8,  37, 45, 300, 302, 303, 311 
See also Combat Intelligence Unit Roehm, E., 225 Rogers, J. H., 291 Rohrbach, H., 217, 222 Rome, 77 
Rommel, D. C. von, 250-252 Ronge, M., 227 Room 40, 130-133, 172, 263 Room 100, 256 Room 2646, 192 
Roos, W. R., 282 Roosevelt, F. D., 29, 48-49, 
50-51,  54-55,  57-58,  62- 
63, 67, 295-296, 298 Rossignol, A., 101-104 Rote Kapelle, 368 Rotors, 204-205, 406 
machines, 207, 209-210, 400 
solution of, 191, 205-206 
See also Damm; Enigma; Hebern; Koch; Scherbius Rotscheidt, W., 236 Rowlett, F. B., 11, 192, 400 R.S.H.A. 
See Reichssicher- 
heitshauptamt Rumrunners, 420-422 Running keys, 127, 199, 200 Russia, 129, 177, 395 
black chambers, 341 
Cold war, 371-377 
cryptanalysis, 367-368 
cryptosystems solved, 350-351, 353-356, 363-367 
Czarist,  341-342 
diplomatic   cryptosystems, 368 
military cryptosystems, 350, 351, 353, 354, 355-356, 362-363, 364 
spy cryptosystems, 368-369, 
371-372, 376-377 World War I, 344-357 World War II, 362-370 
s code, 330-331 
Safford, L. F., 11-12, 192- 
193, 208, 269, 315 Samsonov, A., 346-349 Sandier, R., 259 Samoff, D., 16 Satake, T., 324, 327 Schapper, 
Gottfried, 225 Schauffler, R., 216, 218, 224 Schellenberg, W., 227-228, 
230, 298 
Scherbius, A., 210, 329 Scherschmidt, H., 216 Schimpf, H., 225 Schlusselheft,  155-157,  159 Schutzstaffel  
(S.S.), 225-226 Scientific method, 441 Scramblers, 290-298, 386, 423 S.D. See Sicherheitsdienst SEALION, 
operation, 264-265 Secrecy, 452 Secret Office, 109 Seebohm, A., 253, 254 Segerdahl, E. O., 258, 260 Selchow, 
K., 216, 218 Semagrams, 281, 283-284 Service du Chiffre, 163 Servizio Informazione Mili- 
taire, 246-248 passim Servizio Informazione Segre- 
to, 245 
Sezione 5, 246-248 Sezione 6, 246, 247-248 Shakespeare-Bacon controversy , 184-185, 416, 459 Shannon , C. E., 
407, 443-451 
passim Shaw, H. R., 279-280, 286 
SHESHACH,  72 
Shift registers, 402 Shimizu, Lieutenant, 326 Shoho, 304 
Shungsky, 361 Siam, 77-78 
Sicherheitsdienst, 225-226 Siemens & Halske machine, 237-238, 261-262 
SIGABA,  317 
Signal Intelligence, xv School, 11 
Signal Security, xv 
Signal Security Agency, 273, 274, 317-319 
SIGTOT, 203 
S. I. M. See Servizio Informa-zione Militaire 
Sinkov, A., 192, 320, 329, 390 
S.I.S. (Signal Intelligence Service), 2, 6,7, 11, 23, 25, 28,40,46,266,316-317 
Skeat , W. W., 406 
Skytale, 75-76 
Smith, E. See Friedman, E. S. 
Smith, F. O. J., 111-112 
Smith, L. C., & Corona Typewriters, Inc., 214 
Sonderdienst Dahlem, 217 
Sorge, R., 368 
Sorge ring, 368, 369 
Soro, G., 83 
Soudart, E. A., 159 
Soviet Union. See Russia 
Spain, 84, 357, 424--427 
Speech codes, 289-292 
Spets-Otdel, 359-362 
Spy cipher, 386-370, 371-327, 373, 376 
Square table, 95-96, 99, 100 
S.S. See Schutzstaffel 
Stark, H. F., 4 
Statistics, 189-190, 331, 442 See also  mathematics 
"Steganographia,"   432 
Steganograms, 281-289 
Steganography,   xi,   274-289 
Stein, K., 236 
Stimson, H. L., 4, 6, 178, 183, 457 
Straddling checkerboard, 357-359, 368, 376 
Street, G., 39-40 
Strip cipher. See CSP-642; M- 
138 
Strong, L. C., 437 Subh al-a 'sha, 80 Substitution 
basic solution of, 82-83 compared with transposition,  404 definition, xi See also Monoalphabetic substitution;     
Polyalpha-betic substitution; Transposition Suetonius, 77 Suez crisis, 398-399 Superencipherment, definition, 
xiv 
See also Enciphered code Superimposition.   See   Kerck- 
hoflfs superimposition Svensson, E., 11 Sweden,  210,  256-263, 363- 
364 SYKO, 240, 241 
Tableaux, 95-96, 98-99 Tabula recta, 95-96 Tabulators. See  computers and 
tabulators Tannenberg, Battle of, 348- 
349 T.D.S. See Time-division 
scramble 
Technical Operational Division, 279-280, 281, 286, 
288 
Telconia, 129 
Telegraph, 111-114, 154-155 Telegraphic Japanese, 27 Telephone  secrecy,  289-298, 423 
See also Wiretapping Teletype Corporation, 210 Teletypewriter, 193-198, 237- 
238 
Terminology, 190-191 Thailand,  77-78 
Thiele, F., 233, 236 
13040 (German code), 137, 
143, 144, 148 Thucydides, 76 Tibet, 77 Time, 453-454 Time-division scramble, 293 Times,  The  (London), 414- 
415 T.O.D. (Technical Operations 
Division),   279-280,   281, 
286, 288 (Togo, S., 30, 43^*4, 61 jTojo, H., 30-31, 43 fTokumu Han,  322-327 Tombstones, 412 Tomographic 
ciphers, 121-122 Traicte des Chiffres, 98 Traffic analysis, xv, 8-10, 232, 
305-306, 321-322, 326- 
327 
Traffic volume, 317-318, 407 Transmission security, definition, xi Transposition, 80, 238, 413 
compared with substitution, 404 
defined, xii 
See also Skytale; Substitution 
Trithemius, J., 95-97 xsu. See J series Tsukikawa,   S.,   39 Tuchman, B. W., 458 Turkey, 219, 224, 228-229, 
231, 248, 263 
U-158, 269 
17-505, 270-271 
U-boats,  132-133, 243-244, 
269-272 Unbreakable cipher, 199-202, 
216, 388 
Unicity distance, 450 Unicity point, 450 United States, 191, 379 
Air Force 389, 400 
Army, 15, 389 
cryptosystems, security of, 
389-390, 402 
cryptosystems solved,  110, 221-222,   231,   238-239, 241, 248-256, 325, 332 Navy, 14, 315-316, 381, 389 
See also A.F.S.A.; Army Security Agency; Code and Cipher Compilation Section; Code and Signal Section; 
Combat Intelligence Unit; Federal Communications Commission; FRUPAC; G.2 A.6; Mi-8; National Security 
Agency; OP-20-o; Radio intelligence companies; S.I.S.; Signal Security Agency: T.O.D. Univacs, 394 Uruk, 72 
Van Deman, R. H., 168 
Vatican, 91, 177, 224 
Vatsyayana, 72 
Venice, 83 
Vernam, G. S., 193-203, 329 
system,  193-198, 202-203, 
406 
Verne, J., 416 Video scramblers, 386 Viete,  F., 84-86 Vigenere, B. de, 97-99 Vigenere cipher, 97-100, 403, 
406, 415, 440 Vinay, E., 197 Voge, R. G., 331 Voice communications, 289- 
298 
Volapuk, 125 _ Volunteer Evaluation  Office, 
232 
von der Osten, Ulrich, 276 von Feilitzen, O., 258 von Neumann , J., 451 Voynich, E., 439 
Voynich  manuscript,  428- 
439 
Voynich, W., 432, 439  Vries , M. de, 440, 452 
Waberski, P., 171 Walsingham, Sir Francis, 86- 
89 Wanderer Werke machine, 
237 
Warburg, C. G., 257 Washington  Disarmament 
Conference, 175-177 Wave-form modification, 293 Weather-forecast codes,  Japanese, 42, 322 
Wehrmachtnachrichtenver- 
bindungen, 232-233 Welker, G. W., 13 Wendland, V., 236 Wesemann, 243 Wheatstone, C., 117-118, 121, 
415 Wheatstone cryptograph, 118, 
187 
Wigg, G., 398  Wilkins , J., 438 Willes, E., and family, 106- 
108, 111, 113 Willoughby, C. A., 378 Wilson,  Woodrow,   137-138, 
140-141,  145,   153,  168 Winds code, 31-32, 34-35, 
42-43 
Wiretapping, 289 Witzke, L., 171 W.N.V. See Wehrmachtnach- 
richtenverbindungen Wobble scramble, 293-294 Wolfe, J. R., 458 Women's Army Corps, 313 Woodward, F. C., 45, 
300 World War I, 129-167, 168- 
172,  186-188,  344-357 
World War H, 1-68, 214-340, 
362-370 Wright, W. A., 45, 300, 302, 
310-311, 333 
"Wurlitzer   Organ,"   286-287 Yale University, 439 Yamamoto, I., 7, 299-300, 
308, 314 
assassination, 332-338 Yamanashi, 327 Yamato, 331-332 Yardley, H. O., 167-168, 
172-173, 181-183 American Black Chamber, 
The, 30, 179-181 characteristics, 167-168 chief   of   American   Black 
Chamber, 6, 173-180 chief of Mi-8, 168-172 in China, 182-183, 323 interest in cryptology, 167- 
169 
"Japanese Diplomatic Secrets," 181 later life, 182-183 solves Japanese codes, 173- 
177 
Voynich manuscript, 433 "Yardley symptom,"  168 Yezidis, 77 
Yoshikawa, 15, 39, 44-45, 49 YU, 175-176 Yugoslavia, 246-247 
Zacharias, E. M., 192-193 Zapp, Prof., 288 Zenith Radio Corporation, 0075 (German code), 134, 
137,   139,   140,   142,   143, 
145, 148 
Ziegenriiger, J., 218-219 Zim, H. S., 458 Zimmermann telegram,  134- 
153, 263 Zipf, G. K., 445 
 
THE HISTORY 
OF SECRET CODES— 
AND THE MEN WHO HAVE 
CREATED AND BROKEN 
THEM WITH DRAMATIC 
CONSEQUENCES 
FOR THE WORLD! 
"THRILLING!" 
-CINCINNATI ENQUIRER 
"A LAVISH, NOTABLE ACHIEVEMENT!" 
-THE NEW YORK TIMES 
-.-THE CLASSIC IN ITS FIELD!" 
-CLIFTON FADIMAN, BOOK-OF-THE-MONTH CLUB NEWS 
 
"Comprehensive and astounding ... utterly fascinating 
to anyone interested in political or military history, mathematics, mystery or pure who-dun-it—
Beginning wii 
hieroglyphics and ending with computers, David Kahn 
has produced an anthology of a hundred detective stories, 
one more ingenious than the last, and all real> central 
to the fate of armies and kingdoms. 
-THE WASHINGTON POST 
"SUCH FASCINATION THAT THE READER MAY FIND 
HIMSELF NEGLECTING HIS WORK, BEING LATE 
TO DINNER, AND UNABLE TO GET TO BED AT A 
REASONABLE  HOUR." 
-NEWSWEEK 
SELECTED BY THE BOOK-OF-THE-MONTH CLUB 
NEW AMERICAN LIBRARY PUBLISHES SIGNET, SIGNETTE, MENTOR, CLASSIC, PLUMES NAL BOOKS 
                                                      
1 Not the same thing as the American name J for the J series of Japanese codes. 
2 Whence, apparently, its codename. In American prewar military and naval parlance, the 
codeword ORANGE meant Japan in official papers such as war plans, and even in personal letters 
between high-ranking officers. In the 1930s, Lieutenant Jack S. Holtwick, Jr., a Navy cryptanalyst, 
built a machine to solve a Japanese diplomatic cipher that was abandoned in 1938. American 
cryptanalysts could very naturally have called it the ORANGE machine. As the successors of this 
system appeared, each increasingly enigmatic, their American codenames might well have 
progressively deepened in hue. 
3 This is the literal translation made by Mr. Cory of GZ and given in MAGIC. But Friedman and 
others have contended that it does not take into account the Japanese tendency to speak in 
circumlocution and by indirection. The spirit of it might better be rendered into English, Friedman 
suggested, as "on the brink of catastrophe" or "on the verge of disaster." Kramer conceded that 
the words should not be interpreted as mildly as the English seems to indicate, but could imply 
"relations are reaching a crisis." The British translated this phrase as "Relations between Japan 
and (name of country) are extremely critical." 
4 This may be why Rochefort did not simply request the keys from Washington via the special 
monitors' channel. 
5 The correct plaintexts were simply and, with the extra nd probably an inadvertent repetition, and 
China, it must, with the LYL probably a codeword for comma. 

Document Outline

• Contents
• A Note on the Abridged Version
• Preface
• A Few Words
• 1. One Day of Magic:  I
• 2.  One Day of Magic:  II
• 3.  The First 3,000 Years
• 4.  The Rise of the West
• 5.   On The Origin  of a  Species
• 6.  The Era of the Black Chambers
• 7.  The Contribution of the Dilettantes
• 8.  Room 40
• 9.   A War of Intercepts
• 10. Two  Americans
• Secrecy for  Sale
• 12. Duel in the Ether:  I
• 13  Duel in the Ether:  II
• 14. Censors,  Scramblers, and Spies
• 15. The Scrutable Orientals
• 16 Russkaya Kriptologiya
• 17. N.  S.  A.
• 18. Heterogeneous Impulses
• 19. Ciphers in the Past Tense
• 20. The Anatomy of Cryptology
• Suggestions for Further Reading
• Index