| Clifford Cocks | |
|---|---|
| Born | 28 December 1950 Prestbury, Cheshire, United Kingdom |
| Nationality | British |
| Fields | Cryptography |
| Known for | RSA encryption |
Clifford Christopher Cocks, CB[1], (born 28 December 1950[2] [3]) is a British mathematician and cryptographer at GCHQ. He invented the widely-used encryption algorithm now commonly known as RSA, about three years before it was independently developed by Rivest, Shamir, and Adleman at MIT. He has not been generally recognised for this achievement because his work was by definition classified information, and therefore not released to the public at the time.
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In 1968, Cocks won Silver at the International Mathematical Olympiad while at Manchester Grammar School. Cocks went on to study mathematics as an undergraduate at King's College, Cambridge and then did graduate work at the University of Oxford, where he specialised in number theory, but left to join CESG, an arm of GCHQ, in September 1973.
At GCHQ, Cocks was told about James H. Ellis' "non-secret encryption" and further that since it had been suggested in the late 1960s, no one had been able to find a way to actually implement the concept. Cocks was intrigued, and invented, in 1973, what has become known as the RSA encryption algorithm, realising Ellis' idea. GCHQ appears not to have been able to find a way to use the idea, and in any case, treated it as classified information, so that when it was reinvented and published by Rivest, Shamir, and Adleman in 1977, Cocks' prior achievement remained unknown until 1997.
In 2001, Cocks developed one of the first secure identity based encryption (IBE) schemes, based on assumptions about quadratic residues in composite groups. The Cocks IBE scheme is not widely used in practice due to its high degree of ciphertext expansion. However, it is currently one of the few IBE schemes which do not use bilinear pairings, and rely for security on more well-studied mathematical problems.
As of 2003, Clifford Cocks held the post of Chief Mathematician at GCHQ. He was made a Companion of the Order of the Bath in 2008 (the citation describes him as "Counsellor, Foreign and Commonwealth Office")[1], and was awarded an honorary degree from Bristol University in 2008.[4]