Click for homepage
USA
  
M-94   CSP 488
Strip cipher device - this page is a stub - wanted item

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.

The M-94 consists of 25 circular discs, each with a different mixed alphabet, placed on a com­mon spindle. 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 at 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.
  

A similar device, issued in 1946 by the Swiss Army, is known as Front-Chiffrier­gerät or FG. The M-94 was used until approx. 1942, after which was replaced by the M-209 cipher machine, also known as CSP-1500 — the military variant of the Hagelin C-38 pin-and-lug cipher machine.

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

Inventors
The principe behind the M-94 seems to have been (re)invented at several moments in history:

  • 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).
Manufacturers
  • 1921 (2000 units)
    Doehler Die Casting Company, New York
  • 1928 (1094 units)
    Reeve Electrical Company,New York
  • ? (6338 units)
    Alcoa
Users
  • M-94
    1921 >
    US Army
  • CSP-488
    1928 >
    US Navy
  • CSP-493
    1939 >
    US Coast Guard
References
  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 2018.
  1. Declassified 2 March 1987 by Director NSA, per Sec. 3, E.O. 12356.

Further information
Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Last changed: Sunday, 31 December 2023 - 17:28 CET.
Click for homepage