Bombe

In the history of cryptography, the bombe was an electromechanical device used by British and American cryptologists to help break German Enigma machine signals during World War II. The bombe was designed by Alan Turing, with an important refinement subsequently contributed by Gordon Welchman.

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The bombe was named after, and inspired by, a cryptological device that had been designed by Polish cryptologist Marian Rejewski, known as the bomba kryptologiczna (cryptological bomb).

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A standard services Enigma employed, at any one time, a set of three rotors, each of which could be set in any of 26 positions. The bombe tried each possible rotor position and applied a certain test. The test eliminated nearly all the 26 ? 26 ? 26 = 17,576 possible positions of the three rotors; the few potential solutions were then examined by hand. In order to use a bombe, however, a cryptanalyst first had to produce a "crib" – a section of ciphertext for which he could guess the corresponding plaintext.

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History of cryptography: The history of cryptography dates back thousands of years, and for the most part, it has been the history of classical cryptography; that is, methods of encryption which can be performed using pen and paper (or perhaps with simple mechanical aids). In the early 1900s, the invention of several comple...

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