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Gretag KFF-58/68   TC-58
Online cipher machine - under construction

KFF-58 was an electromechanical online cipher machine, developed by Gretag AG in Regensdorf (Switzerland) in 1958, as the successor to the TC-53. Like the TC-53, the cipher unit is wheel-based, but introduces automatic synchronisation of the cipher stream, making it more suitable for use on noisy HF communication links. The machine was initially developed for the Swiss Army, but was also sold to the Austrian Army, albeit without the special key production device (SPG).

It consists of a KFF-58 teleprinter and an TC-58 cipher attachment, which is placed on top.

The image on the right shows a typical TC-58 unit. It has 12 small windows through which the cipher wheels are visible: 4 on the left, which are the actual scramblers, and 8 on the right which control the stepping, just like on the TC-53.

Below the wheels are two rows of switches. The lower row (i.e. the black switches) are used to set the initial position of the wheels. Unlike the TC-53, where the wheels can only be stepped forward, the wheels of the TC-58 can be stepped in both directions.
TC-58 cipher add-on for the KFF-85

Unlike the TC-53, which was used as a separate device aside an ETK teleprinter, the TC-58 was designed to go on top of the KFF-58 teleprinter and for a complete -single- unit.

Teleprinter (Fernschreiber) KFF-58
Cipher attachment (TC-58)
Key production unit (SPG)
HF radio station SE-222
Teleprinter   KFF-58

Cipher attachment   TC-58
TC-58 cipher add-on for the KFF-85

Key production unit (SPG)
When using the TC-58, the operator had to set the machine to the daily key (Grundstellung) plus an additional randomly picked message key. Due to the way in which the brain works however, such keys are hardly ever random.

For this reason, Gretag developed the SPG, a small key generator that could be mounted at the left of the front panel of the TC-58. It was secret and was only supplied to the Swiss Army.

 More information
Schlüsselproduktionsgerät (SPG). Click for more information.

Radio   SE-222
Although the KFF-58 can be used with virtually any type of shortwave (SW) radio system, it was commonly used in combination with the SE-222 station made by Zellweger in Uster (Switzerland).

 More information

  1. KFF-58A Bedienungsanleitung
    Nr. 1018a. 15 August 1958.
  1. Walter Schmid, Der Krypto-Funk-Fernschreiber KFF-58
    October 2008.
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© Crypto Museum. Created: Friday 03 November 2017. Last changed: Saturday, 24 February 2018 - 08:48 CET.
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