Misattributed to a 16th century French diplomat, it was actually first described by Giovan Batista Belaso. In order to make frequency analysis more difficult, it uses a table of 26 Caesar ciphers and a repeating keyword so that a given letter in the plaintext can be encoded as multiple ciphertext letters at different places in the message. For 10 points, name this polyalphabetic cipher that was thought unbreakable for nea
Misattributed to a 16th century French diplomat, it was actually first described by Giovan Batista Belaso. In order to make frequency analysis more difficult, it uses a table of 26 Caesar ciphers and a repeating keyword so that a given letter in the plaintext can be encoded as multiple ciphertext letters at different places in the message. For 10 points, name this polyalphabetic cipher that was thought unbreakable for nearly 300 years, until methods of attack were independently devised by Charles Babbage and Friedrich Kasiski.
Misattributed to a 16th century French diplomat, it was actually first described by Giovan Batista Belaso.
the {Vigenère} cipher