Hello, -- T. William Wells writes: -- Well, since I'm here, I thought I'd satisfy a curiosity of mine. Has anyone done any research, formal or informal, on the use of genetic algorithms to break cyphers? If not, would anyone care to discuss how it might be done? GA's (which I love, but you won't be able to tell from the following) are a 'robust' search mechanism better at finding _good_ answers than _the_ answer. Because genetic search is driven by partial reward from a partially correct solution, GA's are not adept at searching a space that is very flat except for the single 'spike' of the correct answer. Good encryption systems are like this. You are either right or wrong, no in between. Being one bit off in the key should give a totally fruitless result. GA's don't help much with such ciphers. However, in simple substitution ciphers, frequencies and patterns in partial decryptions can provide the reward GA's need to climb the hills. In fact, Spillman, Janssen, Nelson and Kepner wrote an article in the January 1993 Cryptologia titled "Use of a Genetic Algorithm in the Cryptanalysis of Simple Substitution Ciphers" in which they found that, for the particular class of problems they were solving, within (a short) 100 generations, the GAs could bring the cipher text to the point where a human could 'just read it', whatever that means. Scott Collins | "Few people realize what tremendous power there | is in one of these things." -- Willy Wonka ......................|................................................ BUSINESS. voice:408.862.0540 fax:974.6094 collins@newton.apple.com Apple Computer, Inc. 1 Infinite Loop, MS 301-2C Cupertino, CA 95014 ....................................................................... PERSONAL. voice/fax:408.257.1746 1024/669687 catalyst@netcom.com