Siemens & Halske T52

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T52 in Bletchley Park
T52d of the Imperial War Museum in London

The Siemens & Halske T52 , officially known at the time as the "key teleprinter" (SFM), previously also known as the "secret writer" , is a rotor key machine that was used in the Second World War for the secret transmission of radio telex . She was given the code name Sturgeon (" sturgeon ") by British and American cryptanalysts . A total of between 600 and 1200 machines were produced.

While the Enigma - machine was used primarily by mobile troops for tactical messages T52 came on the command level of the Air Force used. Originally developed for the German navy , the Luftwaffe used the heavy and voluminous machine from 1942 and operated it stationary, similar to what the army did with the Lorenz key addition SZ 42 .

In contrast to the Enigma, in which the result of the encryption had to be read off, written down and (there as Morse code ), these steps were carried out automatically with the T52. The operator only had to enter the text, after which it was encrypted by the machine and sent as encrypted telex characters . Upon receipt, the machine was also able to decrypt and print it out. One of the advantages was this simple operation, the user on either side with the key text itself came into contact.

In contrast to the T43 (also from Siemens & Halske), which worked with a one-time pad , the plain text of the T52 was mixed with a machine- generated key for encryption . To this end, five independent served Binary - pseudo-random numbers generators. In contrast to the Enigma, the rollers of the T52 are not wired and do not conduct any electrical current themselves. Instead, they have a large number of changeable pins which, depending on their position, close an electrical circuit or not.

The machine gained some prominence in the history of cryptography . For various reasons it was only partially deciphered . It was broken independently by the Swede Arne Beurling and by cryptanalysts in Bletchley Park . The Wehrmacht began during the war one among themselves incompatible variants T52a, T52b, T52c, T52ca and T52d. Variants a and b were cryptographically weak. The T52d, on the other hand, was a significantly improved device that no longer had the glaring errors recognized by its predecessors, such as a small hand crank to reset the key unit, which resulted in a large number of encrypted messages being sent with the same key . The system was significantly weakened by repeated inexpedient operation, also with regard to key selection and other reductions in the key space .

literature

  • Bengt Beckman: Arne Beurling and Hitler's secret writer. Swedish deciphering successes in WWII. Springer, Berlin et al. 2005, ISBN 3-540-23720-8 .
  • Wolfgang Mache: The Siemens secret writer - a contribution to the history of telecommunications 1992: 60 years of the key teleprinter . Archive for German Postal History , Issue 2 (1992), pp. 85–94. PDF; 4.6 MB . Retrieved January 19, 2017.
  • Klaus Schmeh : Code breakers versus code makers. The fascinating story of encryption. 2nd Edition. W3L-Verlag, Herdecke et al. 2008, ISBN 978-3-937137-89-6 , p. 174.
  • Frode Weierud : Sturgeon. The FISH BP Never Really Caught . In: David Joyner (Ed.): Coding Theory and Cryptography. From Enigma and Secret Scribe to Quantum Theory . Springer, Berlin et al. 2000, ISBN 3-540-66336-3 (English, cryptocellar.org [PDF; accessed on January 19, 2017]).

Web links

Commons : Siemens T-52  - collection of pictures, videos and audio files