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Crypto AG
Bulk encryption device · CRYPTOPLEX - this page is a stub

MCC-314 was a bulk encryption device, developed in the late 1960s by Crypto AG (Hagelin) in Zug (Switzerland), with help from the Zentralstelle für das Chiffrierwesen (ZfCh) — the German crypto authority — in Bad Godesberg (near Bonn, Germany). The latter developed the encryption algorithm, which had a built-in weakness (backdoor) that made it exploitable (readable) by ZfCh.

The device is housed in a rugged green die-cast aluminium enclosure, and was usually combined with one or more eight-channel multiplexers. It allows full-duplex point-to-point connections with a data transfer rate of 2 Mb/s, similar to the Philips Mucolex or the American TED — KG-81.

The image on the right shows an MCC-314, as it was used for training at Crypto AG in the early 1970s. The hinged door at the left gives access to an 8-level paper tape reader that is used for loading the cryptographic keys. An old brochure shows the device as part of a complete setup [1].
Close-up of an MCC-314. Photograph kindly supplied by [3].

The MCC-314 was introduced around 1972 and was in production until at least the late 1970s. Being a bulk encryption device, it was mainly used by military customers, such as the armies of Austria and Yugoslavia. In 1974, some customers discovered the weakness in the algorithm and complained. It was promptly fixed by a CAG-employee, who got himself in trouble with that [2].

Close-up of an MCC-314. Photograph kindly supplied by [3].
MCC-314 as part of a complete setup [1].
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Close-up of an MCC-314. Photograph kindly supplied by [3].
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MCC-314 as part of a complete setup [1].

Development of the MCC-314 was started in the late 1960s, at a time when the company was still owned by its founder, Boris Hagelin. But as there were strong ties to the American and German intelligence services, it was decided that the German cipher authority – the Zentralstelle für das Chiffrierwesen (ZfCh) – would design the cryptologic (the part that holds the crypto-algorithm). It was developed in parallel with the CSE-280 voice encryptor that used a similar cryptologic [2].

The algorithm had a built-in weakness that was developed by experts at the ZfCh. It made the device readable to them (ZfCh) and later – after Crypto AG had been purchased by the BND and CIA – also to the American National Security Agency (NSA), giving them an obvious advantage.

The weakness in the cryptologic is an exploitable implementation of the forward synchronisation scheme. Head of R&D at Crypto AG – Peter Frutiger – never liked the implementation and felt that it was too obvious. In 1974 Crypto AG found out that Frutiger had been right, when the Austrians and Yugoslavs had both discovered the weakness themselves. When they reported it, Frutiger fixed the flaw in the algorithm and delivered it to his customers, to great concern of the NSA.

With the fix in place, NSA was no longer able to read the targeted traffic. They contacted the CAG CEO and urged him to get a grip on his people, but since Frutiger and his men were officially unwitting of any CIA/BND involvement, there was little they could do. Frutiger did the same two years later to the CSE-280 voice encryptor of the Syrian Army, and subsequently got fired.

  1. Mehrkanal-Chiffriergerät MCC-314 CRYPTOPLEX, brochure (German)
    Crypto AG, date unknown. 1
  1. Document kindly provided by [3].

  1. Crypto AG, Company brochure
    Date unknown, but probably 1976. 24 pages. p.9.

  2. Crypto Museum, Operation RUBICON
    February 2020.

  3. Anonymous, personal correspondence
    August 2020.
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Crypto Museum. Created: Wednesday 01 January 2020. Last changed: Tuesday, 11 August 2020 - 06:45 CET.
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