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The idea for the machine came from Bjørn Rørholdt, Colonel, engineer,
veteran and liason of the Norwegian Army. In close collaboration with
Kåre Meisingset at STK, the idea was further developed, resulting in 1952
in a patent for a new cipher machine with One-Time Tape
[1].
Other NATO countries were immediately interested in this new
cipher machine and ETCRRM soon became a standard crypto device within NATO.
If the machine was used properly, i.e. with a truely random key tape that
would only be used once,
it was truely unbreakable.
Three different versions of the ETCRRM were manufactured over the years,
each with minor differences and improvements.
They were identified by the addition
of a Roman number (I, II and III) to the model name.
The image on the right shows a typical ETCRRM-II.
A standard Creed paper tape reader is mounted to the front panel of the
machine, but there are also versions where the reader is detached. The
key tape is fed into the reader from a reel that is mounted to the right
of the machine.
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ETCRRM also played an important role in the Cold War.
After the Cuban Missile Crisis in 1962, it was decided to establish a
permanent direct telex line between the White House in Washington (USA) and
the Kremlin in Moscow (Russia). The hotline
became operational in 1963
and four ETCRRM machines were used on a daily basis for many years.
Each country communicated in its own language, using (modified) Siemens
T-37 teleprinters. The hotline was first used in 1967 during the
six-day Egypt-Israel war. It was upgraded with more modern equipment in 1976
[2].
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In telegraphy, each letter (or: character) is represented by a pattern
of 5 bits, often stored on a paper tape as a series of punched holes.
Most systems follow the Baudot
standard for this. Each character from
the keyboard, or from a reader that contains the plain-text tape, is
mixed with one character from a key-tape. The key-tape contains random
characters, and the two characters are mixed bit-wise by means of an
XOR operation (modulo-2 addition). At the receiving end, a copy of the
original key-tape is mixed with the cipher-text in order to reveal the
plain-text.
As transistors were not yet available in the early 1950s, the electronic
XOR-circuits inside the ETCRRM largely consist of 12AT7 electronic valves
(tubes), some relays and selenium diodes. Some good photographs of the
interior of the machine can be found on Jerry Proc's website [3].
Although it is claimed in [1] that the principle behind the ETCRRM is a
Norwegian invention, this is unlikely. So far, we haven't been
able to find the 1952 patent of the machine, and numerous other patents for
similar devices, using the same principle, have been filed long before.
During WWII, for example, Siemens developed the
T-43,
which was also a mixer machine.
All these inventions are based completely or in part on patent US1,310,719
of 1919 by Gilbert Vernam.
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© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Monday, 28 January 2013 - 23:52 CET
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