M-325 Explained

M-325
Invent-Date:	1944^[1]
Type:	rotor machine

In the history of cryptography, M-325, also known as SIGFOY,^[2] was an American rotor machine designed by William F. Friedman and built in 1944.^[3] 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;^[4] 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.

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.

Notes and References

1. Book: F.L. Bauer. Decrypted Secrets: Methods and Maxims of Cryptology. 9 March 2013. Springer Science & Business Media. 978-3-662-03452-1. 133–.
2. Book: Friedrich Ludwig Bauer. Decrypted Secrets: Methods and Maxims of Cryptology. 2002. Springer Science & Business Media. 978-3-540-42674-5. 137–.
3. Book: Karl Maria Michael de Leeuw. Jan Bergstra. The History of Information Security: A Comprehensive Handbook. 28 August 2007. Elsevier. 978-0-08-055058-9. 407–.
4. Book: Friedrich L. Bauer. Decrypted Secrets: Methods and Maxims of Cryptology. 24 November 2006. Springer Science & Business Media. 978-3-540-48121-8. 151–.