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The Siemens & Halske T52, also known as the Geheimfernschreiber ("secret teleprinter"), or ''Schlüsselfernschreibmaschine'' (SFM), was a World War II German cipher machine and teleprinter produced by the electrical engineering firm Siemens & Halske. The instrument and its traffic were codenamed ''Sturgeon'' by British cryptanalysts. While the Enigma machine was generally used by field units, the T52 was an online machine used by Luftwaffe and German Navy units, which could support the heavy machine, teletypewriter and attendant fixed circuits. It fulfilled a similar role to the Lorenz cipher machines in the German Army. The British cryptanalysts of Bletchley Park codenamed the German teleprinter ciphers Fish, with individual cipher-systems being given further codenames: just as the T52 was called ''Sturgeon'', the Lorenz machine was codenamed ''Tunny''. ==Operation== The teleprinters of the day emitted each character as five parallel bits on five lines, typically encoded in the Baudot code or something similar. The T52 had ten pinwheels, which were stepped in a complex nonlinear way, based in later models on their positions from various delays in the past, but in such a way that they could never stall. Each of the five plaintext bits was then XORed with the XOR sum of 3 taps from the pinwheels, and then cyclically adjacent pairs of plaintext bits were swapped or not, according to XOR sums of three (different) output bits. The numbers of pins on all the wheels were coprime, and the triplets of bits that controlled each XOR or swap were selectable through a plugboard. This produced a much more complex cipher than the Lorenz machine, and also means that the T52 is not just a pseudorandom number generator-and-XOR cipher. For example, if a cipher clerk erred and sent two different messages using exactly the same settings — a ''depth of two'' in Bletchley jargon — this could be detected statistically but was not immediately and trivially solvable as it would be with the Lorenz. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Siemens and Halske T52」の詳細全文を読む スポンサード リンク
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