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US electronic cipher machine
- this page is under construction
KW-7 was an electronic on-line cipher machine, developed by the
National Security Agency (NSA) in the
USA around 1960.
The device was used on on-line teleprinter networks and was the
main cipher machine of the US Navy until the 1980s.
It is also known as TSEC/KW-7 and as Orestes.
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The KW-7 was housed in a rather heavy cubical metal enclosure,
with all connections at the rear, and its controls at the front.
The cryptographic key had to be set by wiring a plugboard that
was installed behind the heavy door at the front.
In the early 1960s, the machine was one of the first fully-electronic
cipher machines that were used by NATO.
Although it was cryptographically
more secure than the earlier wheel-based KL-7,
the latter remained in service with many army units and with NATO.
Despite its better security, the KW-7 was
compromised for many years.
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The KW-7 was used by the US Navy, but also by the Naval forces
of other NATO countries, such as German and The Netherlands.
The KW-7 was phased-out from the mid-1980s onwards, with the last
machines being decommissioned in 1988. They were largely replaced
by the KG-84, which in turn was replaced in the
mid-1990s by the much smaller and compatible KIV-7.
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The following variants of the KW-7 are known to exist:
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- Wire-cord version
The original version of the KW-7 had a plugboard behind the door at
the front. Each day, the key had to be set by patching the plugboard
according to the daily keylist. This was not very practicle, as it
took the machine out-of-service for several minutes whilst a new
key was being 'programmed'. This version had a 'flat' front door.
- Plug-block version
At some point the KW-7 was modified with a removable plug-block at
the front. The plug-block assembly was constructed in such a manner,
that it could be slotted into the existing patch sockets, e.g. as
a field-upgrade.
The advantage of a removable plug-block is that several blocks can
be prepared (i.e. wired) well in advance of changing the key.
This version can be recognized by a front door which
has a small square bulge at the center.
The machine featured on this page is of this type.
- Punched-card reader version
A later improvement consisted of a punched paper card reader, which
replaced the plug-block mentioned above. This version has a front
door with a wide rectangular bulge.
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Althoug the KW-7 can be controlled completely from its front panel,
the machine was often mounted in a 19" rack, together with other
equipment, or even in a different room. In order to control the
machine from the terminal (teletype), a separate remote control
box was used.
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The image on the right shows a KWX-7/TSEC remote control panel.
It connects to the KW-7 by means of two thick cables and has
the same controls and connections as the device itself.
The top row of the remote unit, consists of four indicator lamps:
a red one that indicates Plain Text mode, a green one that shows
that the device is in Cipher mode (secure), a red ALARM lamp
that lights in case of a failure and an orange lamp marked P&I.
The mode of operation is selected with the rotary knob at
the bottom left. At the bottom right is the SEND button.
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At the bottom center is a large button marked BREAK.
It should be pressed in case of an emergency.
It disables all output and prevents any further
data (clear or cipher) from being sent. A break condition
can only be reset by pressing the small black BREAK RESTORE button.
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During its lifetime, KW-7 was compromised several times.
Based on publicly available research [1],
it seems most probable that the Russians were able to read (break) messages
encrypted with a number of high-level US cipher machines, including
the KL-7,
the KL-47
and the KW-7.
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The most famous story of cipher compromise is that of John Anthony
Walker, born 1937, who worked for the US Navy and successfully spied for the
Russians for nearly 17 years [2].
Walker joined the US Navy in 1955 and started spying for the Soviets in
December 1967, when he had financial difficulties [3].
From that moment, until his retirement from the navy in 1983,
he supplied the Russians with the key lists and other critical cipher
material of the KL-47,
the KW-7 and other cipher machines.
For his information he received several thousand dollars from the Soviets
each month. In 1969 he began searching for assistance and befriended
Jerry Whitworth, a student who would become a Navy Senior Petty Officer.
In 1973, he was able to enlist Whitworth in his spy-ring.
In 1976, Walker left the Navy to become a Private Investigator (PI), but kept
spying for the Russians. By 1984, he had recruted his older brother Arthur
and his son Michael, who kept the endless flow of classified documents going.
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He also tried to recruit his youngest daughter who had started to work
for the US Army, but this attempt failed when she became pregnant and
abandoned her military career.
Earlier, around 1976, Walker and his wife Barbara divorced.
When he refused to pay alimony in 1985, Barbara tipped-off the FBI,
which eventually led to Walker's arrest.
After his arrest, Walker cooperated with the authorities
and pleaded guilty, in order to lower the sentence of his son Michael.
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US Embassies all over the world used KW-7 and other cipher machines
for secure communication with the Home Office back in the US. Cipher
personnel were trained in the operation of the KW-7, but also in its
demolition in case of an emergency. They were instructed not to
let any operation machines fall into enemy hands and had to destroy
any critical components in such an event.
Following the Iranian Revolution, after which Persian
became an Islamic Republic on 1 April 1979 [4],
a group of angry students supporting the revoluton,
raided the US Embassy in Tehran (Iran) on 4 November 1979
and took 52 of the US Embassy staff hostage for more than a year.
As the raid came rather unexpectidly, communications personnel
had to rush in order to get all crypto gear destroyed in time.
The image above shows part of the communications room in the embassy,
with a KW-7 unit clearly visible at the front. It has been pulled
out of the 19" rack, the top has been removed and the critical
cipher board have been taken out and destroyed.
At the right, on the floor, are the destructed key card readers
of the KW-7.
In the same way, all technical documentation and key lists had to
be destroyed as well. In this case, no critical components fell into
enemy hands and the KW-7 was not compromised. Eventually, after
long negotiations, the hostages were released on 20 January 1981,
after being held for 444 days [5].
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- TM 11-5810-221-12P - Operator's and Organizational Maintenance Repair...
...Parts and Special Tools Lists and Maintenance Allocation Chart:
Communications Security Equipment TSEC/KW-7, TSEC/KW-7 with KWX-10/TSEC.
NSN 5810-00-998-5760.
- KAM-143B/TSEC - Repair and Maintenance Instructions for TSEC/KW-7
Volume I - Description, Installation & Theory of Operation.
- KAM-144B/TSEC - Repair and Maintenance Instructions for TSEC/KW-7
Volume II - Preventive Maintenance Troubleshooting and Diagrams.
- KAM-145C/TSEC - Repair and Maintenance Instructions for TSEC/KW-7
Volume III - Illustrated Parts List.
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- Laura H. Heath, Analysis of Systematic Security Weaknesses of the US Navy...
M.S., Georgia Institute of Technology, 2001.
Fort Leavensworth, Kansas (USA), 2005.
Thesis of Major Laura Heath, detailing how John Walker exploited weaknesses
in the US Navy Broadcasting System between 1967 and 1974.
- Pete Earley, Family of Spies: The John Walker Jr. Spy Case
TruTV website, crime library. Date unknown.
- Wikipedia, John Anthony Walker
Retrieved November 2010.
- Wikipedia, Iranian Revolution
Retrieved October 2013.
- Wikipedia, Iran hostage crisis
Retrieved October 2013.
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© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Sunday, 19 January 2014 - 11:05 CET
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