Homepage
Crypto
Index
Glossary
Enigma
Hagelin
Fialka
Nema
Voice
Hand
OTP
EMU
Mixers
Phones
FILL
Codebooks
Algorithms
USA
USSR
UK
Yugoslavia
Ascom
AT&T
Bosch
Datotek
Gretag
HELL
ITT
Motorola
Mils
OMI
Philips
Racal
Siemens
STK
Tadiran
Telsy
Teltron
Transvertex
TST
Spy radio
Burst encoders
Intercept
Covert
Radio
PC
Telex
People
Agencies
Manufacturers
• • • Donate • • •
Kits
Shop
News
Events
Wanted
Contact
About
Links
   Click for homepage
Gretacoder 524
64 kb/s serial link encryptor

Gretacoder 524 was a link encryptor, developed by Gretag in Regensdorf (Switzerland) in the early 1990s. It was intended for the continuous encryption and decryption of serial (RS232) data at speeds up to 64 kb/s (synchronous). It was available with a variety of interface options.

All controls are at the front panel, together with two security modules (SM), left and right, and a physical key. The physical key locks the right SM and prevents the case from being opened. The user interface consists of a series of buttons and an 2-row LCD display at the top left.

The image on the right shows the front panel of a typical Gretacoder 524. The case and the front panel layout is identical to that of the later (and faster) Gretacoder 605. It is also identical to the later X.25 variant, the Gretacoder 545 [1], although the case of the latter was grey.
  
Gretacoder 524

The Gretacoder 524 was part of a range of encryption devices that were released over time, consisting of the 522, 524, 526 and 605 models, that are more or less (backwards) compatible with each other, differing only in speed and interface. To allow customization, the interface was generally implemented as a separate daughter card, making the unit suitable for wide range of applications and networks. The device shown here supports the X.21 standard.

In 1991, Gretag was acquired by AT&T (USA) and became known as AT&T Gretag Data Systems AG, hence the reason for the AT&T logo on the front panel. AT&T also took care for the US sales of the Gretacoder range. The 524 was succeeded by the improved and faster Gretacoder 605 in the mid-1990s. By that time the company was taken over by IRE and the AT&T logo disappeared.

Gretacoder 524 Gretacoder 524 front panel AT&T logo on the front panel Unlocking the rightmost plug-in Removing the rightmost plug-in Leftmost plug-in Serial number plate at the bottom

Protocols
Please note that the Gretacoder 524 does not contain a physical MODEM. It can only encrypt serial data in a variety of formats, but needs an external modem in order to connect it to the outside world (e.g. via telephone lines). Two separate proprietary connectors are available at the back. The leftmost one connects to the device that needs to be protected (plain text), whilst the rightmost one delivers the cipher text.

The Gretacoder supports two encryption standards: (1) Gretag's own proprietary block cipher with a key length of 64 or 128 bits, or (2) industry standard DES with a key length of 56 bits [2]. The latter was supplied for customers who wanted an industry standard, despite the fact that by the early 1990s DES increasingly became critisized as being unsafe. The in-house developed 128 bit key block cipher provided much stronger security.

Interior
The Gretacoder 524 is built inside a rather neat cream metal case, that measures only 22 x 7 x 36.5 cm. The case consists of two parts: A metal frame holding the PCBs and the front panel, and a cream outer shell. The latter is held in place by just two large bolt at the rear.

The outer shell can only be removed when the two bolts are taken out and the physical key (at the right of the front panel) is released. The internal frame holds the front panel and two PCBs: the Main PCB at the bottom and a smaller interface board at the top.

Depending on the customer's requirements, a different interface board would be used. The interface connects to the main PCB by means of a 40-pin ribbon cable. The interface shown here has two proprietary rectanglular connectors, marked PLAIN and CIPHER.
  
Gretacoder 524 interior

At the heart of the main PCB is the M80C154 microcontroller, which is compatible with the industry standard 8051. Several supporting chips are present (e.g. RAM and serial interfaces) and the firmware is contained in EEPROM. Encryption and decryption is implemented in two custom chips on the main PCB.

At the rear, the main PCB has a female DB9 socket marked REMOTE CONTROL. The purpose of this socket is currently unknown, but it seems to be a standard asynchronous RS-232 port, probably used for a controlling terminal. The PCB was designed to hold two DB25 connectors but these are unused in this version of the 524 as the function is taken over by the interface board. Apparently, the DB25 connectors were hardly used as they were omitted in later designs.

Gretacoder 524 interior Gretacoder 524 interior Inside of the physical lock that blocks the rightmost security plug-in as well as the outer shell of the case Main PCB top view Interface board Removing the interface board Processor and oscillator Custom chips

Help required
As Gretag is no longer in business, background information about the company and its devices are very hard to find. Unfortunately, we have no further information about this device at present. If you have more, different or better information, please contact us. Your help is appreciated.

References
  1. Gretacoder Data Systems AG., Gretacoder 545, X.25 Data Encryption
    4-page sales brochure. April 1997.

  2. Cyberspace Policy Institute, Growing Development of Foreign Encryption Products
    10 June 1999. p. 44. Retrieved March 2012.

  3. OKI Semiconductor, M80C154 processor datasheet
    CMOS 8-bit 8051-compatible microcontroller. January 1998. Retrieved March 2012.

  4. Wikipedia, X.21 Standard
    Retrieved July 2012.
Further information
Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Last changed: Friday, 19 April 2013 - 08:39 CET.
Click for homepage