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Gretacoder 603
Bulk Encryption Device

The Gretacode 603 was a bulk encryption device developed by Gretag in Regensdorf (Switzerland) in the mid-1980s. It was intended for the encryption of fast multiplexed telephone and data channels at speeds between 32 kbits/s to 2 Mbits/s. The Gretacoder 603 is based on the military Gretacoder 601. Data is exchanged in full-duplex time-division multiplex.
 
The system consists of two 19" rack-mount units; one for either side of the communication link. Each unit has a multiplexed input (MUX) and is probably capable of enciphering both voice and data signals.

The system is clearly derived from similar military devices, as it is partly green and has typical military connectors. Several keys can be loaded into the machine simultaneously by using a key filler.

More images below.
  

Not much is known about this Gretacoder 603 system. According to a former owner, it was used for communication via satellite between two bank sites; one in Switzerland and one in the far-east. You can help us to extend this page by providing additional information.
 
The complete unit Front panel of the Gretacoder 603 Close-up of the control panel MUX cable

 
Loading the key
Devices like the Gretacoder 603 generally store they crypto-key in the internal memory. The key itself is generated elsewhere and is loaded into the device by means of a so-called key fill device, or key-filler.
 
With this crypto-set, two devices were supplied that are related to the key-loading operation. The first one is the external key filler (or possibly a key generator) that is shown here. The other one is a simple switch, mounted on a military connector. This switch was probably used to select which key was being loaded or overwritten (see image below).

Furthermore, as set of key are supplied with each machine. These were used to switch between cipher and plain-text mode.
  

A red button is present on the front panel. It was probably used to select the required key, or to delete all crypto variables in case of an emergency.
 
Key loading device Key selector switch

 
Further information

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Crypto Museum. Last changed: Thursday, 12 July 2012 - 06:48 CET.
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