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M-94   CSP 488
Strip cipher device - this page is a stub

M-94 was a military hand-operated poly-alphabet substitution cipher, also known as a strip cipher device, 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.

The device consists of 25 circular discs, each with a different mixed alphabet, placed on a common axle. Forthis 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 its circumference, and is identified by the letter that follows the 'A'.

The M-94 was manufactured by several companies. Although the exact procurement figures are unknown, ASA's cryptographer William Friedmand reported in 1943, that a total of 9432 had been manufactured.

  1. Somewhere between September 1916 and August 1917 [1].

  • Thomas Jeferson
    President of the United States.
  • Etienne Bazeries
    Commandant in the French Army.
  • Parker Hitt
    Captain in the US Army.
  • Joseph O. Mauborgne
    Major (later: Major General) in the US Army. Chief, Engineering and Research Division, Office of the Chief Signal Officer (afterwards: Chief Signal Officer).
  • 1921 - (2000) Doehler Die Casting Company, New York
  • 1928 - (1094) Reeve Electrical Company,New York
  • Alcoa
  • US Army (M-94) - 1921
  • US Navy (CSP-488) - 1928
  • US Coast Guard (CSP-493) - 1939
  1. ASA Historian AS-13, The History of Army Strip Cipher Devices 1
    SRH-366. July 1934 - October 1947.
    Army Security Agency, Washington (USA), November 1948.

  2. Jerry Proc's crypto pages, M-94 (CSP-488)
    Retrieved May 2018.

  3. Wikipedia, M-94
    Retrieved May 218.
  1. Declassified 2 March 1987 by Director NSA, per Sec. 3, E.O. 12356.

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