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How a Caius Fellow helped secure the internet

  • 15 June 2016

A Caius Fellow awarded the “Nobel Prize of Computing” for his ground-breaking work enabling secure internet communications is featured in a new film celebrating the award.

Whitfield Diffie, a GC Steward Visiting Fellow at Caius in 1996, received the Association for Computing Machinery’s 2015 AM Turing Award in March this year. The prestigious $1 million award was shared with Martin E. Hellman, Professor Emeritus of Electrical Engineering at Stanford University, and recognised the “critical contribution” of the pair to modern cryptography.

The two researchers are interviewed in a film and article in the association’s latest magazine, Communications of the ACM.

Diffie and Hellman were decades ahead of their time, publishing a paper on electronic encryption in 1976 – years before the subject would become a preoccupation of governments, companies and billions of internet users anxious to keep their data secure. Announcing their award, ACM President Alexander L. Wolf said: “In 1976, Diffie and Hellman imagined a future where people would regularly communicate through electronic networks and be vulnerable to having their communications stolen or altered. Now, after nearly 40 years, we see that their forecasts were remarkably prescient.”

Encryption allows two parties to communicate privately over an otherwise insecure channel. Individuals rely on it daily to establish secure online connections with banks, e-commerce sites, email servers and the cloud.

Diffie and Hellman’s groundbreaking 1976 paper, “New Directions in Cryptography,” introduced the ideas of public-key cryptography and digital signatures, which are the foundation for most regularly-used security protocols on the Internet today.

The Diffie-Hellman Protocol protects daily internet communications and trillions of dollars in financial transactions.

In encryption, a “key” is a piece of information used to transform readable plain text into garbled and incomprehensible cipher text. In the past, two parties seeking to establish secure communications needed identical keys: one to encode and another to restore the text. Diffie and Hellman’s crucial breakthrough was to show that asymmetric or “public-key” cryptography was possible, with a public, non-secret key used for encryption and a private one for decryption. In reverse, a transmitter of a message uses a private key to sign it, while the receiver uses a public key to authenticate it – thus creating a secure “digital signature” linked precisely to that one message.

The research not only laid the foundation for today’s online security industry and established cryptography as a leading discipline within computer science, but also made encryption technologies accessible to individuals and companies.

Diffie, former vice president and chief security officer of Sun Microsystems, describes himself as a hippie with “much more anti-societal views” at the time of the 1976 paper than now. Just a year after publication, he joined Hellman in presenting papers at an international conference on information theory in defiance of US National Security Agency claims that their new approach to encryption would violate US law prohibiting the export of weapons to other countries.

"This was just absolute nonsense, that you could have laws that could affect free speech," Diffie says. "It was very important to defy them."

* A previous joint winner of the Turing Award - named after Alan Turing, the British mathematician who was a key contributor to the cracking of the German Enigma code – was Michael Rabin, a GC Steward Visiting Fellow at Caius in 2004.

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