A simple demonstration of a frequency attack on a Vigenère cipher implemented in Haskell. This attack is based on the Friedman test and frequency analysis.
Call decodeVigenere code 5 to decode the cipher text code with a maximal key length of 5.
The cipher text code is:
GGAAKWRJTUWQHWSGAOAADBFTCGLYSFGWRCGLYASPGNSARZANTLHNLCBFTESRLLOJZAGOEGWNQLOGZIACPRGPYWNBLOADYPSRRLHRQCNJENDOGLHRHRBTLREIFOESWEYVIFWMCGWRJEQOESWEYDIXWWRUAALDBSNLLHVFGNTOHLIGKOJWMNQAFOEYDNBLTEQIGKGBANTLOOWAYGNTHRBUEFKBHLTUSTFLAELIAYTBUHNFGRLHRLEPZNVUAYUOZEUAATLSNQSSCWCVSLFZOHLOHLTBWVRJYHFDRJPNADNFDBNEEOOECEQKTHVEALOHLTUWRROOECIAYOALHVKYBMAEWTUWNBTLRSTYSSYAFGANTMPGZETDOOWIAGUEOIYVLLANRIUVLAODEPMREWNGKYFLEZASVFAYGTBXWNQLRXTUGLQANTLHRTATGNGZIFGNRTYIARGMEBXTUWNNLUEWOSLHRHRBTLRESOMTGZAGKNBLAYDBNVTJGTUGUFSNQLHVJTRWNSGRNDOGGFRFGVFERJSNFDEWSRSRPZEFOAFSKVFDBXAGGMVUMBEEALFBJCBEPHLEEKCVWNPWMHUHYAKRHHLKIPKPBKTZSNUSTGSNCJOWWCGSNRFTVJESAEYVOSJEFWAEUHGZAGOAFTRBSDYQACGLVLIPSLEWAYAZRVTUSTJGRXANGWNQWDGGIZHRBNEGZEUMMNFCBFDVLIBFCBMLQSLFGBRKUONEELEQLOQWGESDRATRVWNJDFFOJVEA