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"The Turing Bombe" Breaking the Enigma cipher at the Bletchley Park museum 2015.

Turing designed the British Bombe in 1939. Compared to the Polish Bomba, it used a completely different approach. It was based on the assumption that a known (or guessed) plaintext, a so-called crib, is present at a certain position in the message. The Bombes were built by the British Tabulating Company (BTM, later ICL) at Letchworth (UK) under the supervision of Harold 'Doc' Keen . The first machine, called 'Victory', was delivered at Bletchley Park on 18 March 1940.

 

The Bombe was further enhanced with the so-called diagonal board, an invention of fellow codebreaker Gordon Welchman, that greatly reduced the number of steps needed for the codebreaking effort. A second Bombe, with Welchman's diagonal board present, was installed on 8 August 1940. It was named 'Agnus Dei', later shortened to 'Agnes' or 'Aggie'. The first machine (Victory) was later modified with a diagonal board as well.

 

During the course of the war, over 200 Turing-Welchmand Bombes were built. To avoid the risk of losing them in case of a bomb attack, they were spread between Bletchley Park and its so-called Outstations in Wavendon, Adstock, Gayhurst, Eastcote and Stanmore, where they were operated by WRNS, RAF-technicians and civillian personnel.

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Uploaded on August 27, 2016
Taken on November 19, 2013