M-325

In the history of cryptography, M-325, also known as SIGFOY,<ref name="Bauer2002">Template:Cite book</ref> was an American rotor machine designed by William F. Friedman and built in 1944.<ref name="LeeuwBergstra2007">Template:Cite book</ref> Between 1944 and 1946, more than 1,100 machines were deployed within the United States Foreign Service. Its use was discontinued in 1946 because of faults in operation. Friedman applied for a patent on the M-325 on 11 August 1944;<ref name="Bauer2006">Template:Cite book</ref> it was and was granted on 17 March 1959 (US patent #2,877,565).

Like the Enigma, the M-325 contains three intermediate rotors and a reflecting rotor.

File:M-325.png

Friedman patented the design of the M-325 in US patent #2,877,565.

See also

• Hebern rotor machine
• SIGABA

Further reading

• Louis Kruh, Converter M-325(T), Cryptologia 1, 1977, pp143–149.

External links

• Operating and Keying Instructions for Converter M-325(T) Headquarters, Army Security Agency, July 1948, scanned and transcribed by Bob Lord.
• Friedman M-325 — information and photographs.
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