Vigen'ere cipher

In cryptography, a polyalphabetic substitution cipher first published in 1586. This cipher may be considered as a precursor of stream ciphers. Effectively each letter is replaced by a number related to its alphabetic position; the repeated keyword represents the keystream, and the plaintext/keystream numbers are added modulo 26.; 于1586年首次發表的一種多表置換密碼。它可看作是序列密碼的前身。實際上，每個字母用 與它在字母表中位置相關的數代替；以密鑰字重復代表密鑰流，明文/密鑰流的數值進行模2 6加。參閱Vernam cipher。