Back method6.shtml Next Secret-Key Encryption Algorithms Another simple example of a secret-key encryption, Vigenere from the polyalphabetic substitution family: Involves a modification of the Ceasar substitution Start by choosing a small fixed number m, and m shifts of the alphabet. Memorize these shifts of the alphabet with the key that corresponds to the associated cypher letters. ie: with m=4 you could choose ... 1 abcdefghijklmnopqrstuvwxyz ghijklmnopqrstuvwxyzabcdef 2 abcdefghijklmnopqrstuvwxyz opqrstuvwxyzabcdefghijklmn 3 abcdefghijklmnopqrstuvwxyz lmnopqrstuvwxyzabcdefghijk 4 abcdefghijklmnopqrstuvwxyz fghijklmnopqrstuvwxyzabcde key = golf The plaintext is then separated into "chunks" of size m, and each m-gram is successively encrypted by replacing its first letter by the corresponding letter of the first cypher alphabet, the replacing its second letter by the corresponding letter of the second cypher alphabet, ..., and its mth letter by the corresponding letter of the mth cypher alphabet. ie: GETM EOUT OFHE REPL EASE MSER KCFY UTSJ XSAQ KOHJ Copyright 1997 by Slackers Union. Comments should go to any of the group members. Opinions reflected on this page are by no means opinions of UCSD. Go sue somebody else. Last Modified: June 1, 1997