Malcolm Williamson

Together with Clifford Cocks, Malcolm Williamson worked on what was then called Non-Secret Encryption, following a question by James Ellis at GCHQ, as to whether such a concept was possible. 

Clifford Cocks devised the public-key encryption system now known as RSA, and shortly afterwards Malcolm Williamson devised a method of public key exchange, which allows two parties to obtain a common secret key while communicating only in public. 

This is now known as the Diffie-Hellmann key exchange after the academic researchers who independently found it at almost the same time. 

This technique remains at the heart of cyber-security, being used by internet router equipment all over the world to make secure connections.

Malcolm was a brilliant mathematician who competed on the British team in the International Mathematical Olympiad, winning a Gold Medal in 1968. 

He joined GCHQ in 1972 after studying mathematics at Trinity College Cambridge. He moved to the United States in 1982 to work in a mathematical research centre.

He applied his interest in digital signal processing to the development of improved hearing aids, for which he held two patents. 

In 2010 Malcolm, together with Clifford Cocks and James Ellis, received a Milestone Award from the Institute of Electrical and Electronics Engineers (IEEE) for the development of Public Key Cryptography.

GCHQ’s Chief Cryptologist said: "GCHQ is very proud of Malcolm Williamson’s contribution to PKC: the method he invented was, and is, universally used in internet security to this day."

Malcolm died in 2015 and is survived by his wife and son.