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TC-850
Off-line teletype encryptor - this page is a stub

TC-850 was a military off-line device for the encryption and decryption of teletypewriter signals (telex), develop in the mid-1970s by Gretag AG in Regensdorf (Switzerland), as a modern day alternative to the KFF/TC-58. 1 Unlike the KFF-58 – which used a proprietary data format similar to the Gretag ETK – the TC-850 was compliant with the common ITA2 (Baudot) teletype standard.

For this reason, the TC-850 was compatible with most existing teletype equipment on the market. As it is intended for off-line use, it has a built-in paper tape reader and a paper tape puncher, which could be used for loading and saving bulk data. In addition, plaintext and cryptograms could be entered on the built-in keyboard.

The image on the right shows a typical TC-850 ready for use. It was taken from the original instruction manual, and shows the machine without its protective metal dust cover [A]. 		  

Development of the TC-850 started in 1973 and lasted until approx. 1975, after which full production was scheduled for 1977 [2]. It is currently unknown how many devices were made.

  1. Note that the TC-850 is not compatible with the KFF/TC-58.

THIS PAGE IS A STUB — This page currently acts as a placeholder for future information about this machine. If you have any additional information about it, please contact us. We do not have this device in our collection.
Cryptanalysis
It is known that the TC-850 had the attention of the Cuban intelligence services and the East-German Stasi. The firmware of the TC-850 was analysed by the Cubans in 1983, and a suitable simulation was created in the programming language PASCAL. In 1987 the Cubans passed their work on to the Stasi, who tried to convert it into an automated cryptanalysis tool. It is currently unknown whether this attempt was successful or not.

From information found in the German BStU archives, historian Jörg Drobick has meanwhile created a detailed description of the software [3].

➤ Jörg Drobick's analysis (off-site)


Documentation
  1. Chiffriergeraet TC-850 Operating instructions (German/French)
    Gretag AG, August 1975.
References
  1. Gerhard Sulger Buel, TC-803, documentation and background information
    Personal correspondence, June 2013.

  2. Gretag AG, Documents related to the production planning of the TC-850
    Crypto Museum Archive CM-303064/C. 1973 — 1977.

  3. Jörg Drobick, Das Chiffriergerät GRETG TC-850
    Retrieved 23 November 2021.
Further information
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© Crypto Museum. Created: Monday 01 April 2019. Last changed: Saturday, 13 January 2024 - 16:15 CET.
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