TheCodeBreakers
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
annaabi.ee 
