TheCodeBreakers
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.
annaabi.ee 
