The Cryptanalysis of a Three Rotor Machine Using a Genetic Algorithm.

Abstract

This paper describes a method of decipher ing messages encrypted with rotor machines utilising a Genetic Algorithm to search the keyspace A tness measure based on the phi test for non randomness of text is described and the results show that an unknown three rotor machine can generally be cryptanalysed with about letters of ciphertext The results are compared to those given using a previously published technique and found to be superior