Editing RSA cryptosystem (section)

==Patent==

A [[patent]] describing the RSA algorithm was granted to [[Massachusetts Institute of Technology|MIT]] on 20 September 1983: {{US patent|4405829}} "Cryptographic communications system and method". From [[Derwent World Patent Index|DWPI]]'s abstract of the patent:
{{Blockquote|The system includes a communications channel coupled to at least one terminal having an encoding device and to at least one terminal having a decoding device. A message-to-be-transferred is enciphered to ciphertext at the encoding terminal by encoding the message as a number M in a predetermined set. That number is then raised to a first predetermined power (associated with the intended receiver) and finally computed. The remainder or residue, C, is... computed when the exponentiated number is divided by the product of two predetermined prime numbers (associated with the intended receiver).}}

A detailed description of the algorithm was published in August 1977, in [[Scientific American]]'s [[List of Martin Gardner Mathematical Games columns|Mathematical Games]] column.<ref name="SIAM" /> This preceded the patent's filing date of December 1977. Consequently, the patent had no legal standing outside the [[United States]]. Had Cocks' work been publicly known, a patent in the United States would not have been legal either.

When the patent was issued, [[term of patent|terms of patent]] were 17 years. The patent was about to expire on 21 September 2000, but [[RSA Security]] released the algorithm to the public domain on 6 September 2000.<ref>{{cite web |url=http://www.rsa.com/press_release.aspx?id=261 |title=RSA Security Releases RSA Encryption Algorithm into Public Domain |access-date=2010-03-03 |url-status=dead |archive-url=https://web.archive.org/web/20070621021111/http://www.rsa.com/press_release.aspx?id=261 |archive-date=June 21, 2007 }}</ref>