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Gretag, or Gretacoder Data Systems, or simply Gretacoder, was a manufacturer of cryptographic equipment, based in Regensdorf near Zürich (Switzerland). It was founded by Dr. Edgar Gretener who was not only a direct competitor of Boris Hagelin, but also worked with him on a number of occasions. The company, which also made the encryption devices for international SWIFT bank transactions, had a world-wide customer base and had once over 2500 people on its payroll.
Gretag company logo

Gretag produced a range of commercial, industrial and military cipher machines, that were of a remarkable quality and were not rigged by foreign intelligence services like CIA or BND, although the latter two tried to get their hand on Gretag on several occasions. In 1991, the company was eventually taken over – under control of the CIA – by AT&T, and liquidated in 2004 – when it was owned by SafeNet. Before the takeover however, most of the patents had already been transferred to Omnisec AG - a new Swiss company that had been created especially for that purpose. More...

Gretag's cipher machines are known under different names and numbers. Generally speaking, the numbering was never changed, but different prefixes and brand names were used. The name Gretacoder was sometimes abbreviated as 'GC' or 'TC' (for: Tele-Crypto, or Teleprinter Crypto). E.g.: the military 812 telex encryption unit is known as Gretacoder 812, GC-812 and TC-812.

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Gretag cipher machines on this website
Telekrypto-Gerät 35, developed by Edgar Gretener (Gratag) and Boris Hagelin.
One of the first electro-mechanical cipher machines build by Gretener
Gretag KFF-58 with TC-58 cipher attachment
Electronic military telex encryptor
Electronic military telex encryptor
Gretacoder 101, speech scrambler
Gretacoder 103, telephone scrambler
Gretacoder 104, voice scrambler
TC-803 electronic portable off-line teletype encryptor
Gretacoder 805 (portable version)
Gretacoder 805 (desktop version)
Gretacoder 905, portable electronic cipher device
Gretacoder 519 Fax Encryptor (Facsimile Cipher Unit)
Gretacoder 521 for Haslter SP-300 teleprinter
Gretacoder 524 link encryptor (64 kb/s)
Gretacoder 603 bulk encryption device
Gretacoder 605 link encryptor (2048 kb/s)
Gretacoder 715 Message Authenticator
Gretacoder 720, extremely secure DES encryptor for SWIFT transactions
Schlüsselproduktionsgerät (key production device)
Digital circuit blocks
TKG 35   wanted item
Telekrypto-Gerät 35 (TKG) was an online cipher machine for Gretag's proprietary 14-bit teleprinters, such as the ETK-47. It was a joint development of Dr. Edgar Gretener (Gretag) and competitor Boris Hagelin and used Hagelin's pin-wheel system.

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The TC-53 was the first electro-mechanical cipher machine manufactured by Gretag for the Swiss Army. It was based on an earlier design of Dr. Edgar Gretener and competitor Boris Hagelin.

The machine had 12 cipher wheels and used a novel 14-bit technique, rather than the usual 5-bits for transmission of the data.

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TC-53 without the SPG key generator

TC-58   KFF-58
Around 1958, Gretag introduced the TC-58 cipher unit, which could be fitted on top of the KFF-58 teletypewriter. Like its predecessor, the TC-53, it has 12 cipher wheels and uses Gretag's 14-bit data transfer technology, rather than the more common digital 5-bit ITA-2 standard.

The machine was used by the Swiss Army, and also by the Austrian Army.

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

In 1964, Gretag made the move to electronic cipher machines, with the development of the TC-534. It was a military device that consisted of two large watertight boxes, and was built with in-house developed digital building blocks.

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Around 1970, Gretag introduced the first fully electronic portable cipher machine for teletype signals. The device was housed in a standard Samsonite briefcase and was intended for by the intelligence and diplomatic community.

The device was later found to be insecure as it uses linear-feedback shift registers (LFSRs), after which it was succeeded by the Gretacoder 805.

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Gretag TC-803 cipher machine with strip printer

In the mid-1970s, Gretag developed an all-in-one electronic cipher machine for teletype signals, aimed to the replace the KFF/TC-58 which used the (meanwhile) obsolete ETK tele­printer technology.

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Gretacoder 101
The Gretacoder 101, or GC-101, was a modular speech scrambler for telephone and radio links, introduced in 1975. It uses two-dimensional voice scrambling and was based on the earlier SC-101 from 1973.

The device is suitable for half-duplex only, which is controlled by a Push-To-Talk (PTT) switch in the handset.

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Gretacoder 101

Gretacoder 103
The Gretacoder 103, or GC-103, was a voice scrambler for analogue telephone lines. It is inserted between the phone and the line.

It uses time-domain as well as frequency-domain scrambling and was manufactuered as an OEM product by Telsy in Italy. It is identical to the Telsy TDS-2004.

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Telsy TDS-2004

Gretacoder 104
The Gretacoder 104, or GC-104, was a voice scrambler for mobile use. It uses time-domain as well as frequency-domain scrambling and was manufactuered as an OEM product by Telsy in Italy. It is identical to the Telsy TDS-2004M.

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Gretacoder 805   portable
The Gretacoder 805 was a small portable electronic cipher machine that was fitted inside a standard Samsonite briefcase, together with a small thermal printer.

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Gretacoder 805

Gretacoder 805   desktop
As the Gretacoder 805 had a highly modular design, a variety of different configurations were possible. For the office, a large desktop version could be created, complete with a papertape reader/puncher ans shown here.

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Complete Gretacoder 805 desktop system with paper tape reader/puncher on the left

Gretacoder 905
Gretacoder 905 was the first fully-electronic portable cipher machine, produced by Gretag in 1976. It has a display with 32 LEDs and features just three push-buttons and one rotary switch.

The GC-905 was a direct competitor of the Hagelin HC-520.

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Gretacoder 905

Gretacoder 519
Gretacoder 519 was one of the first fax encryption devices on the market. It was introduced in 1984 and was inserted between a modem and the actual fax machine. It was suitable for speeds up to 9600 baud.

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GC-519 in desktop enclosure

Gretacoder 524
Gretacoder 524 was a line encryptor for synchronous (RS-232) serial links, developed in the early 1990s when Gretag was part of AT&T. It supports continuous data encryption at rates up to 64 kb/s and was available with various interfaces and (software) options.

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Gretacoder 524

Gretacoder 603
This 19" rackmount system, consisted of two units. One for either side of the communication link. It was used to encypher and decypher multiplexed data streams over satellite links.

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Gretacoder 605
Gretacoder 605 was a line encryptor for synchronous (RS-422) serial links, developed in the mid-1990s when Gretag was part of IRE (Now: SafeNet). It supports continuous data encryption at rates up to 2048 kb/s and was available with various interfaces and options.

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Gretacoder 605

Gretacoder 720
Gretacoder 720 was a highly secure DES encryptor for international bank-to-bank payments (SWIFT). It was housed in a large strong 19" case and was highly tamper-proof.

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Gretacoder 720

Known Gretag equipment
Below is a non-exhaustive list of the various Gretag devices we've identified so far. Initially all cipher machines were built under the Gretag brand. Later the name was changed to Gretacoder, which was sometimes abbreviated as 'GC'. In the overview below, 'GC' stands for Gretacoder, whilst 'TC' stands for 'Tele Crypto' or 'Teleprinter Crypto'. Found another one? Please let us know.

Encryption devices
  • 1951
    Telecrypto mechanical cipher machine
  • 1953
    Telecrypto electromechanical cipher machine (ETK)
  • 1958
    Telecrypto electromechanical cipher machine (KFF)
  • TC-61
    Later development of KFF/TC compatible with 5-bit baudot
  • QRG-101
    Quasi-random generator
  • RAG-101
    Random Generator
  • PTR-101
    Paper-tape reader
  • LUSD-68
    ETK-ITA2 converter
  • TC-812
    Military telex encryptor
  • 1975
    Electronic telex encryptor
  • SC-101
    Voice scrambler
  • 1975
    Voice scrambler (mobile)
  • 1975
    Voice scrambler (mobile)
  • SC-201
    Voice encryptor
  • GC-202
    Voice encryptor
  • GC-210
    Voice encryptor
  • GC-505
    Teletype encryptor (compatible with GC-805)
  • GC-515
    Block cipher (SWIFT payments)
  • GC-517
    Data encryptor
  • GC-518
    Link encryptor
  • 1984
    Fax encryptor
  • 1980
    Teleprinter encryptor
  • 1992
    Serial X.21 link encryptor
  • 1964
    Military speech encryptor (uses building blocks)
  • GC-545
    X.25 data encryptor
  • GC-549
    X.25 data encryptor - Network Security Center (NSC)
  • GC-555
    Frame Relay Encryptor
  • GC-601
    Military block cipher
  • 1979
    Civil block cipher
  • 1995
    V.35 Link data encryptor
  • GC-650
    High-speed link encryptor
  • GC-700
    Highly secure link encryptor (SIA Italian inter-bank)
  • 1989
    Highly secure link encryptor (SIC Swiss inter-bank)
  • 1998
    Highly secure link encryptor for SWIFT payments
  • TC-800
    Portable electronic telex encryptor (prototype of TC-803)
  • TC-801
  • TC-802
  • 1968
    Portable electronic telex encryptor
  • TC-804
  • 1978
    Portable off-line encryptor
  • 1978
    Desktop off-line encryptor
  • PTR-810
    Paper-tape reader
  • HSP-830
    Paper-tape puncher
  • 1974
    Pocket encryptor (compatible with GC-805)
  • GC-906
    Pocket encryptor with keyboard (compatible with GC-805)
  • GC-915
    Off-line authenticator for banks
Photo equipment
  • D-1
  • CGC-501
  1. Gretag full-colour company brochure
    October 1969. 16 pages.

  2. Sales leaflet, Gretacoder Security Systems
    Gretag AG, September 1979.
  1. Ulrich Rimensberger, Datensicherung durch Chiffrierung
    Description of the Gretacoder 515, published at the 5th International Congress for Data Processing in Europe. Vienna, 21-25 March 1977.

  2. Gretacoder Data Systems AG. Gretacoder 650, High-Speed Link Encryptor.
    2-page sales brochure. August 2000.

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

  4. The Free Library, IRE Acquired Gretag Data Systems AG
    11 June 1995, Retrieved march 2012.

  5. Dr. John H. Nugent, Curriculum Vitae
    Member of Board of Directors at AT&T Gretag 1991-1993.
    31 March 2007. p. 6. Retrieved march 2012.

  6. Walter Schmid, Der Krypto-Funk-Fernschreiber KFF-58
    October 2008.
Further information
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© Crypto Museum. Created: Thursday 06 August 2009. Last changed: Tuesday, 11 April 2023 - 06:22 CET.
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