Milestone-Nomination:Invention of Public-key Cryptography


Docket Number: 2008-15

Proposal Link:

Proposed citation in English

Invention of Public-key Cryptography, 1969-1975

At GCHQ, by 1975 James Ellis had proved that a symmetric secret-key system is unnecessary and Clifford Cocks with Malcolm Williamson showed how such 'public-key cryptography' could be achieved. Until then it was believed that secure communication was impossible without exchange of a secret key, with key distribution a major impediment. With these discoveries the essential principles were known but were kept secret until 1997.

Historic significance of this work: its importance to the evolution of electrical and computer engineering and science and its importance to regional/national/international development.

Historical significance and supporting material documentation is attached. 

What features or characteristics set this work apart from similar achievements?

The research was carried out in complete secrecy at GCHQ and could not be revealed until it was decided that no further benefit to national security could be achieved by not revealing it. Like the cryptanalysis done during World War 2 at Bletchley Park (now an IEEE Historical Milestone site, since March 2003), the significance of the work was available for public assessment only long after the research was actually carried out. The work by Diffie & Hellman at Stanford and by Rivest, Shamir & Adleman at MIT was published later.

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