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Strip cipher device
- this page is a stub
M-94 was a polyalphabetic manual substitution cipher device for tactical
messages, developed around 1917 1
by US Army major Joseph O. Mauborgne, and manufactured by several companies,
including Doehler, Reeve and Alcoa.
It was introduced to the US Army in 1921
and is based on a 1795 invention by (then) US President Thomas Jefferson.
It offers limited cryptographic security.
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The device consists of 25 circular discs, each with a different mixed alphabet,
placed on a common axle. For this reason,
the device is also known as a revolving discs cipher.
Each disc has the 26 letters of the
Latin alphabet engraved in a different (randomized) order on the outer rim,
and is identified by the letter that follows the 'A'.
M-94 was manufactured by several companies.
Although the exact procurement figures are unknown, ASA's cryptographer
William Friedman
reported in 1943, that a total of 9432 units had been manufactured
for use by the US Army.
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Somewhere between September 1916 and August 1917 [1].
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The principe behind the M-94 seems to have been (re)invented at several
moments in history:
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- Thomas Jeferson · 1795
President of the United States.
- Etienne Bazeries
Commandant in the French Army.
- Parker Hitt
Captain in the US Army.
- Joseph O. Mauborgne · 1917
Major (later: Major General) in the US Army.
Chief, Engineering and Research Division, Office of the Chief Signal Officer
(afterwards: Chief Signal Officer).
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1921 (2000 units) Doehler Die Casting Company, New York 1928 (1094 units) Reeve Electrical Company,New York ? Alcoa
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- US Army (M-94) - 1921 onwards
- US Navy (CSP-488) - 1928 onwards
- US Coast Guard (CSP-493) - 1939 onwards
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Declassified 2 March 1987 by Director NSA, per Sec. 3, E.O. 12356.
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© Crypto Museum. Last changed: Wednesday, 12 August 2020 - 17:18 CET.
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