3 May 2006
William F. Friedman was long-time head of cryptology at the US Army predecessor of the National Security Agency. The first two patents below were classified until late 2000; there may be others still secret.
Discussion of Patent No. 6,097,812:
http://cryptome.org/nsa-crypto33-2.htm
| No. | PAT. NO. | Inventor, Title, Granted, Filed | |
| 1 | 6,130,946 | -- William F. Friedman, Cryptographs. Assigned to the
National Security Agency. Classified until granted October 10, 2000. Filed
October 23, 1936.
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| 2 | 6,097,812 | -- William F. Friedman, Cryptographic
system. Assigned to the National Security Agency. Classified until
granted August 1, 2000. Filed July 23, 1933.
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| 3 | 2,877,565 | 380/52 -- W.F. Friedman, Electrical Cryptograph.
Granted March 17, 1959. Filed August 11, 1944.
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| 4 | 2,552,548 | 380/244 178/17D -- W.F. Friedman, Facsimile Enciphering
System. Granted May 15, 1951. Filed March 6, 1943.
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| 5 | 2,518,458 | 380/59 -- W.F. Friedman, Authenticating Device.
Granted August 15, 1950. Filed August 25, 1944.
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| 6 | 2,465,367 | 380/243 -- William F. Friedman, Joseph O. Mauborgne,
System for Enciphering Facsimiles. Granted March 29, 1949. Filed March
12, 1943.
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| 7 | 2,395,863 | 380/56 -- W.F. Friedman, Cryptographic Device.
Granted March 5, 1946. Filed October 19, 1939.
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| 8 | 2,224,646 | 209/583 209/657 234/75 235/454 235/462.25 235/492 235/494
250/555 340/5.1 -- W.F. Friedman, V.E. Whitman, Electric Control System
for Tabulating Cards, Documents and the Like. Gratned December 10, 1940.
Filed April 22, 1937.
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| 9 | 2,166,137 | 200/17R 200/11R 200/501 335/74 476/13 -- William F.
Friedman, Frank B. Rowlett, Electrical Switching System. Granted July
18, 1939. Filed August 19, 1935.
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| 10 | 2,140,424 | 380/57 -- W.F. Friedman, Cryptographic Device.
Granted December 13, 1938. Filed June 7, 1937.
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| 11 | 2,139,676 | 380/26 -- W.F. Friedman, Cryptographic Apparatus.
Granted December 13, 1938. Filed August 4, 1937.
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| 12 | 2,080,416 | 380/27 380/52 -- W.F. Friedman, Message Authentication
System. Granted may 18, 1937. Filed June 26, 1935.
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| 13 | 2,028,772 | 380/26 380/51 -- William F. Friedman, George A. Graham,
Cryptographic System. Granted January 28, 1936. Filed January 23,
1932.
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| 14 | 1,857,374 | 380/27 380/51 400/473 -- George A. Graham, Louis M.
Evans, William F. Friedman, Cryptograph Enciphering and Deciphering
Device. Granted May 10, 1932. Filed March 28, 1929.
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| 15 | 1,694,874 | 370/302 -- W.F. Friedman, Method of Electrical
Signaling, Granted December 11, 1928. Filed July 10, 1922.
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| 16 | 1,608,590 | 283/17 283/115 380/59 -- W.F. Friedman, Alphabetical
Chart, Granted November 30, 1926. Filed January 7, 1926.
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| 17 | 1,530,660 | 375/260 370/302 -- W.F. Friedman, Printing Telegraph
System. Granted March 24, 1925. Filed July 26, 1922.
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| 18 | 1,522,775 | 380/27 380/47 -- W.F. Friedman, Secret Signaling
Apparatus for Automatically Enciphering and Deciphering Messages. Granted
January 13, 1925. Filed April 14, 1922.
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| 19 | 1,516,180 | 380/27 380/47 -- W.F. Friedman, Secret Signaling
System Employing Apparatus for Automatically Enciphering and Deciphering
Messages, Granted November 18, 1924. Filed June 5, 1922.
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| 20 | 1,503,250 | 375/369 -- Paul E. Sabine and W. F. Friedman, Apparatus for and Method of Rapid Transmission of Telegraphic Messages, Granted July 29, 1924. Filed August 7, 1920. |