Reminiscences and Reflections of a Codebreaker

Many books have now been published about the work of the Bletchley Park codebreakers during World War II. Outstanding among these are Alan Turing: The Enigma, by Andrew Hodges [Ho], a sensitive and enormously informative biography of a genius who made a unique contribution to winning the war while he was simultaneously inventing the computer; and Codebreakers, edited by F. H. Hinsley and Alan Stripp [Hin], a series of articles providing detailed information on the methods employed by the codebreakers of Bletchley Park. Particularly to be commended among the latter is the article by Professor I. J. (Jack) Good, entitled “Enigma and Fish”, in which Jack, one of the key members of the teams working first on Naval Enigma and then on the even more sophisticated Geheimschreiber code (which we called Fish!), describes the machines employed by the Germans and the machines we developed to help to read messages encrypted by these machines. It is a great advantage, of course, for those able, like Jack Good, to provide precise descriptions of these machines and of our methods, that much of the necessary information has now, at long last, been declassified.