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US rotor-based cipher machine
KL-7 was an electro-mechanical rotor-based off-line
cipher machine, developed by the
National Security Agency (NSA) in the US. It was
introduced in 1952 and served for many years as the main
cipher machine of the US and NATO. It is relatively
light-weight (9.3 kg) and is basically a more advanced
version of the
German Enigma machine. It was a replacement for the
SIGABA.
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The initial name for the machine was AFSAM-7, but
changed to TSEC/KL-7 in the early 1960s. It is
also known by key-procedure codenames ADONIS
(high-level) and POLLUX (low-level). KL-7 was
withdrawn from service in 1983.
Unlike Enigma, the KL-7 has eight rotors, seven of which
are moved in a complex irregular
stepping pattern. The machines came in several
variations and were used by the US Army, Navy and NATO
for many years. They were also used for communication by
Foreign Affairs.
Unfortunately, KL-7 still is a classified item and only
few of them have survived. Most machines that are on
public display, have been 'sanitized', and all wiring
has been removed. |
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Despite the secrecy surrounding the KL-7 and its
history, the mystery is gradually being unravelled as
the NSA releases more and more historical documents and
researchers manage to uncover more and more technical
details of the machine. As a result, a reaslistic computer simulation of the KL-7 is
now available from crypto-historian Dirk Rijmenants in
Belgium.
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