Q&A: The encryption pioneer who was written out of history

In the early 1970s, three men working for the British Government developed an encryption system that – almost 40 years later – underpins every transaction on the internet. There was only one problem: they couldn’t tell anyone about it.

Q&A: The encryption pioneer who was written out of history

Between them James Ellis, Clifford Cocks and Malcolm Williamson invented Public Key Cryptography, a system that permits secure communications and electronic transactions without the prior exchange of a secret key. Their work was used to secure Government communications – and naturally their bosses at the Government Communications Headquarters (GCHQ) wanted to keep their discovery top secret.

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Thus, the trio were practically written out of history when in 1976, Martin Hellman, Ralph Merkle and Whitfield Diffie from Stanford University began publishing similar theories in the US.

A year later, Ron Rivest, Adi Shamir and Leonard Adleman from the Massachusetts Institute of Technology developed the Stanford team’s theory even further and the RSA encryption algorithm, which secures billions of transactions on the internet every day, was born.

The British trio’s amazing breakthrough remained under wraps until the late 1990s, when it was revealed that they had beaten the Americans to the punch. Today, their work is finally being given the recognition it deserves by the The Institute of Electrical and Electronics Engineers (IEEE), who are awarding the GCHQ trio a Milestone Award, a prestigious honour that has previously been bestowed on breakthroughs such as the Bletchley Park Enigma machine and the first transatlantic TV broadcast.

To mark the occasion, Clifford Cocks has spoken to PC Pro about the trio’s amazing discovery and the difficulties of watching someone else take the credit.

Q. When you first developed Public Key Encryption, did you have any idea of the scale of what you’d invented?

A. At the time I don’t think anyone had an idea of how big things like the internet would be. The motivation was very much in the context of reducing the cost of key management, which is something that CESG [the Communications-Electronics Security Group], part of GCHQ, was responsible for.

So I was thinking in terms of what cryptography was almost entirely used for then, which was governmental and military [communications]. The idea of this huge amount of civil use and use over the internet for e-commerce, we really didn’t have any insight into that.

Q. What did it feel like when the Americans came along and ‘invented’ something you had achieved years previous?

A. The first I knew about it was when I read about it in Scientific American. I opened it one lunchtime and saw a description and thought ‘Ah, that’s what we did’.

You don’t go into the GCHQ business to get external credit and recognition – quite the opposite. Quite honestly, the main reaction was one of complete surprise that this had actually been discovered outside.

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