IEEE honours GCHQ public key crypto inventors

A prestigious engineering body has honoured three former employees of British intelligence agency GCHQ for the invention of public key cryptography.

The Institute of Electrical and Electronics Engineers (IEEE) held one plaque-unveiling ceremony on Monday and will be having another on Tuesday to honour James Ellis, Clifford Cocks and Malcolm Williamson. The Monday ceremony was held in private in the main body of GCHQ [Government Communications Headquarters], while the Tuesday ceremony will be public and held at the Pittville Pump Rooms in Cheltenham. James Ellis' widow accepted the award in his place.

Clifford Cocks will be honoured for coming up with public key cryptography. Photo credit: David Meyer

Public key cryptography is extensively used to encrypt online financial transactions. In public key cryptography, data is encrypted using a widely distributed public key, and can be decrypted using a private key.

Cocks told ZDNet UK on Thursday that Ellis had published the concept of what Ellis called "non-secret encryption" in 1969, while Cocks had come up with the method of public key cryptography in 1973.

"I thought the function has to be easy to do and difficult to undo," said Cocks. "It you multiply prime factors, you can only undo [the encryption] if you know the factors."

Cocks said that he had thought of the method one evening, but had not written it down.

"I kept it in my head and hoped to remember it in the morning," said Cocks.

Professor Peter Hill of Cranfield University, who is an ex-chair of the IEEE communications group, told ZDNet UK on Thursday that public key cryptography was a very significant invention.

"The awards ceremonies are about the importance of recognising the magnitude of this invention," said Hill.

This will be the one-hundredth IEEE Milestone Award. Previous award subects include the first transatlantic telephone cable, and the first transatlantic satellite TV communication.