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Telekrypto-Gerät 35
Online cipher machine - wanted item

Telekrypto-Gerät 35, or TKG, or GR tg 35, or TC-35, was a cipher machine built by Dr. Edgar Gretener AG (Gretag) in Zürich (Switzerland) in 1951. The device was a joint development of Dr. Edgar Gretener and competitor Boris Hagelin, shortly before the latter founded Crypto AG (1952).
 
The device was intended for sending secure telegrams using teleprinter (telex) systems, but unlike the common 5-bit (Baudot) standard, it used Gretener's proprietary 14-bit technology that was developed for the ETK-47 teleprinter.

The image on the right shows a photograph of the machine, that was recently rediscovered in the former Gretag Archives. At the front are 14 cipher wheels mounted on a shaft. The machine used hagelin's novel pin-wheel principle and Gretener's 14-bit data standard, in which each of the 14 bits represented a part (segment) of a character, that was re-combined in the printer.
  

In 1951, Gretener managed to attract the attention of the Danish Army who ordered 35 machines. Two machines were delivered immediately, whilst the rest was delivered during the course of 1951 [2]. It is currently unknown whether any of these machines have survived. An early prototype is present in the internal collection of Crypto AG (Hagelin) in Zug (Switzerland).

The machine clearly was the predecessor of the TC-53 that was developed for the Swiss Army a few years later (1953). It was a separate device that used the same 14-bit technology and was inserted between the ETK teleprinter and the line. At Hagelin, the development of the Telekrypto 35 eventually led to the TC-52 (note the similar model numbers). Contrary to Getener's TC-53, the Hagelin machine used the more common international 5-bit technology (Baudot or ITA-2).
 
Front view of the Telekrypto 35 Rear view of the Telekrypto 35

 
References
  1. Dr Edgar Gretener AG, Telekrypto-Gerät GR tg 35
    Gretag Archives, 1949-1951. Crypto Museum #CM301792.

  2. Gretener AG, Besprechnungsnotiz vom 30. März 1951
    Minutes of meeting concerning delivery of 35 TKG machines to Danmark (German).
    Gretag archives, 3 April 1951. Crypto Museum #CM301792/A.

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