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The previous 3-rotor Enigma model had been modified with the old reflector replaced by a thin rotor and a new thin reflector. Breaking Shark on 3-rotor bombes would have taken 50 to 100 times as long as an average Air Force or Army message. It seemed, therefore, that effective, fast, 4-rotor bombes were the only way forward.
The top drum corresponds to the left-hand Enigma rotor, the middle drum to the middle rotor and the bottom drum to the right-hand rotor. Wire brushes on the back of a drum from the rebuilt Bombe The bombe was an electro-mechanical device that replicated the action of several Enigma machines wired together.
The German Enigma used a combination key to control the operation of the machine: rotor order, which rotors to install, which ring setting for each rotor, which initial setting for each rotor, and the settings of the stecker plugboard. The rotor settings were trigrams (for example, "NJR") to indicate the way the operator was to set the machine.
A rare 8-rotor printing Enigma model H (1929) There was also a large, eight-rotor printing model, the Enigma H, called Enigma II by the Reichswehr. In 1933 the Polish Cipher Bureau detected that it was in use for high-level military communication, but it was soon withdrawn, as it was unreliable and jammed frequently. [48]
Despite the introduction of the 4-rotor Enigma for Atlantic U-boats, the analysis of traffic enciphered with the 3-rotor Enigma proved of immense value to the Allied navies. Banburismus was used until July 1943, when it became more efficient to use the many more bombes that had become available.
US Navy bombe at the National Cryptologic Museum. Partial schematics of the US Navy bombe.. The United States Naval Computing Machine Laboratory (NCML) was a highly secret design and manufacturing site for code-breaking machinery located in Building 26 of the National Cash Register (NCR) company in Dayton, Ohio and operated by the United States Navy during World War II.
Like Enigma, Typex was a rotor machine. Typex came in a number of variations, but all contained five rotors, as opposed to three or four in the Enigma. Like the Enigma, the signal was sent through the rotors twice, using a "reflector" at the end of the rotor stack. On a Typex rotor, each electrical contact was doubled to improve reliability.
Mathematician-cryptologist Marian Rejewski had already set up a system of equations describing the operation of the then new German Army Enigma rotor-wirings. The key -settings lists provided by Schmidt helped fill in enough of the unknowns in Rejewski's formulae , allowing him to speedily solve the equations and recover the wirings.