TheCodeBreakers
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
annaabi.ee 
