Telex encryption device
- this page is a stub
T-204, codenamed Wolna (Russian: Волна), was an electromechanical
encryption & decryption device
for telegraphy (telex) signals, introduced
by the USSR
around 1962. The device had the size of a large wardrobe,
and was built around drums with five rotors, or cipher wheels.
In the former DDR (East Germany) the T-204 M was introduced in 1966, followed
in 1969 by the T-204 M1. . Following the Six-Day War 1 they
were replaced by the T-205 from 1975 onwards.
As far as we know, there are no surviving examples of the T-204 machine on
The image below shows the cipher mechanism, or drum, as it was rescued
by German collector Immo Hahn from a demolition site in 2009 .
Although the artefact has been damaged badly – and is clearly beyond repair –
its features are still visible. It shows that two sets of five
rotors each were used side-by-side. Like with the
German Enigma cipher machine,
each rotor set is held between two
fixed contact discs.
It is also clear that the rotors had 13 contact points at either side.
The rotors are driven by a
complex cog-wheel driven gear, with a
variety of pawls, notches, levers and actuating solenoids, which makes
it likely that the machine featured irregular stepping of the rotors,
and that the wheels could probably move in both directions, similar to
(but more complex than) the
Russian M-125 Fialka,
in which the wheels move in opposite (but fixed) directions.
In 1975, the T-204 (Wolna) was succeeded by the T-205
— codenamed Wecha
During Six-Day War (5-10 June 1967) between Israel and some Arab countries
(Egypt, Jordan and Syria) an unknown number of
Soviet cipher machines had been captured
by the Israelis. It is believed that eventually it enabled them (possibly with
help from the NSA)
to break the Soviet ciphers, which is why many Soviet
systems were either replaced or modified several years later.
The image below shows one of the original rotors of the T-204,
which is all we currently have of this machine. The wheel is largely
destroyed as part of the demilitarization procedure, but is still good enough
to show its original purpose. Many thanks to Immo Hahn for providing this item
A similar cipher wheel — probably from the same source — is shown in Klaus
Schmeh's excellent book Codeknacker gegen Codemacher .
Further details, photographs and other information is available from
Jörg Drobick's informative website
Der SAS- und Chiffrierdienst (SCD)
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© Crypto Museum. Created: Sunday 24 March 2019. Last changed: Sunday, 24 March 2019 - 17:06 CET.