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
or the American TED — KG-81.
The image on the right shows the MCC-314 in a real-life environment.
The actual encryptor is at the top and is here being loaded with
a cryptographic key, by means of a punched paper tape.
The other devices are AMD-310 multiplexers, each suitable for up to
eight external data lines.
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
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
voice encryptor that used a similar cryptologic
The algorithm had a built-in weakness that was developed by experts at the
It made the device readable to them (ZfCh) and later – after
Crypto AG had been purchased by the
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 unwitting of
the involvement of the intelligence services, 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.
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© Crypto Museum. Created: Wednesday 01 January 2020. Last changed: Monday, 10 February 2020 - 15:04 CET.