Whitfield Diffie and Martin E. Hellman were awarded the 2015 ACM AM Turing Award for their contribution to modern cryptography. The two came up with the public key cryptography, which is at the basis of, for example, pgp, ssl, ssh and ipsec.
Whitfield Diffie and Martin E. Hellman will receive the Turing Award on June 11 from the Association for Computing Machinery and will receive $1 million from Google. In awarding the award, ACM refers to the importance of the 1976 paper Diffie and Hellman: New Directions in Cryptography.
In it, the two elaborate the idea of asymmetric keys. Most decryption techniques have been symmetrical; the same key was used for encryption and decryption. Diffie and Hellman proposed a system where the decryption key, or the private key, was different from the encryption key, or the public key. The latter can then be publicly distributed and used to encrypt messages, after which the private key can decrypt the data.
The two thought of using a special one-way mathematical function, which is reversible only under special circumstances. Ronald Rivest, Adi Shamir and Leonard Adleman elaborated on this with their prime multiplication system. Multiplication is easy, but factoring the prime factors is a time consuming task. This elaboration has come to be known as the RSA security and one of the first practical elaborations of public key exchange. Incidentally, the GCHQ, the British intelligence service, would have come up with the idea for public key exchange earlier, but did not announce it until 1997.
The basis of Diffie and Hellman’s idea is ubiquitous in today’s internet age. Among other things, the security of e-mail with pgp is based on the principle, but also the ssl protocol for the encrypted connection between a client and a web server. VPN techniques such as ssh and ipsec also depend on a public key infrastructure. “In 1976, Diffie and Hellman envisioned a future where people would communicate regularly over electronic networks and would be vulnerable to theft or alteration of communications,” said Alexander L. Wolf, president of the ACM. “Now, after nearly 40 years, we see that their forecasts were remarkably prescient,” he adds.
Whitfield Diffie later went on to serve as chief security officer at Sun Microsystems, while Martin Hellman is an emeritus professor of electrical engineering at Stanford University. Both were awarded the ACM Paris Kanellakis Prize in 1996, along with Leonard Adleman, Ralph Merkle, Ronald Rivest and Adi Shamir.
Photos: Martin E. Hellman (left) and Whitfield Diffie (right)