Clifford Cocks

Clifford Christopher Cocks is a British mathematician and cryptographer at GCHQ who 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 not released to the public at the time.

In 1968, Cocks won Silver at the International Mathematical Olympiad while at Manchester Grammar School. Cocks went on to study mathematics at the University of Cambridge, specialising in number theory, and joined CESG, an arm of GCHQ, in September 1973.

Upon joining — a graduate-school drop-out, aged 22, and a brand new employee at GCHQ — Cocks was told about James 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, thought about it overnight, 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, so that when it was reinvented and published by Rivest, Shamir, and Adleman in 1976, Cocks' prior achievement remained unknown until 1997.

Clifford Cocks currently (2003) holds the post of Chief Mathematician at GCHQ.

External links

• Wired article on public key cryptography at GCHQ
• James Ellis' account of the invention of non-secret encryption
• Cock's internal GCHQ note on his discovery