IN C

1. Compute the frequency ordering of the letters appearing in the ciphertext, and guess a potential decryption key by mapping them to the standard English letter frequency ordering: ETAOINSHRDLCUMWFGYPBVKJXQZ. 2. Analyze the quality of your potential key by counting the number of words from the provided dic- tionary.txt file which appear in the decoded message. 3. Permute the guessed key in order to increase the number of dictionary words the decrypted text contains, until further permutations no longer improve its quality.

ciphertext contains

KEKPRLBNOLMKYBPRGPBMMLTJLJBAZIPTKVRLKPVILIVJBAZWBATVKYBWUSMLIRAKIPVGPBMTPORLIRRL KSJBNCYLIEKJBAZWBATVKYIPSBQRLKATVKPBNOLRBAIGKNVATVRWNVRQNCBQICCBQRLKARLTVTVOBTPO

and dictionary.txt contains all the possible words in the dictionary abigail abigails ability abioses abiosis abiotic abject abjectly abjure abjured abjurer abjurers abjures abjuring ... and so on from a to z