Giants Still Walk Among Us: Diffie and Hellman Awarded Turing

In May the Association for Computing Machinery announced this year’s “Turing Award” goes to Whitfield Diffie and Martin Hellman, recognizing their foundational work (along with Ralph Merkle) on public key cryptography [3].

This is a well-deserved honor, and not just because they are old hippies. The internet could not be used without the ideas of Diffie, Hellman, and Merkle, which are used many times every day by everyone on the web.

Just as important, their first paper, “New directions in cryptography” [1] was a thunderbolt when we read it–in 1976! New, revolutionary ideas, and, for those of use doing distributed systems, a path to solve the two most critical problems we faced. Brilliant! It gave me goose bumps when I first read it a few years later. (Yes, I still remember it.)

It is also hard to realize these days, but the paper was also a political rebellion, apiece with many other developments of the unfairly maligned 1970s. The paper marked a bold defiance of the semi-formal, semi-legal, sort-of-old-boys, wink-wink, control of cryptography held by the NSA, GCHQ, allied, and competing agencies.

When I was a lad, both parallel computing and cryptography were considered weapons of war, and stiffly regulated by the US and other governments. While you may scoff, they had a point: these technologies were, and are, critical for the defense of the nation. But they are basically just good ideas, and it isn’t really possible to monopolize math, not for long.

We would not have the World Wide Web if academics such as Hellman and Diffie, and later the Mosaic crew at NCSA, and many others, had not pushed hard to get public key cryptography out in the world. You are welcome.

I should note that all the whoop-dee-do about Bitcoin and the Blockchain in the past few years is all built on the technology described by Diffie and Hellman in 1976. In many ways, there isn’t much new in Bitcoin except a data structure for passing around cryptographic signatures. That’s a good idea, but no where near as important or innovative as the much older cryptographic signature technology itself.

So let’s credit Bitcoin to Diffie, Hellman, and Merkle, too.

While we’re looking at CACM, I would note the really cool article “Physical Key Extraction Attacks on PCs” by Daniel Genkin, Lev Pachmanov, Itamar Pipman, Adi Shamir, and Eran Tromer [2]. This terrifying work is all about the uncontrolled physical side-effects of computing, which can be snooped and used to extract secrets (such as cryptographic keys).

“The hardware running the program is a physical object and, as such, interacts with its environment in complex ways, including electric currents, electromagnetic fields, sound, vibrations, and light emissions. All these “side channels” may depend on the computation performed, along with the secrets within it. “Side-channel attacks,” which exploit such information leakage, have been used to break the security of numerous cryptographic implementations.” (p. 70)


In case you imagined that public key cryptography solves all problems and makes your digital life secure and private, think again.

Their paper runs through a bunch of ways that you can figure out what the computer is doing based on the leaked electricity, magnetism, and, surprising to me, sound. Wow!

This is a really cool article, and you have to wonder just how crazy they had to be to dream up some of these things to try!

As Hellman says, “My advice, is don’t worry about doing something foolish.”

  1. W. Diffie and M. Hellman, New directions in cryptography. IEEE Trans. Inf. Theor., 22 (6):644-654, 2006.
  2. Daniel Genkin, Lev Pachmanov, Itamar Pipman, Adi Shamir, and Eran Tromer, Physical key extraction attacks on PCs. Commun. ACM, 59 (6):70-79, 2016.
  3. Neil Savage, The key to privacy. Commun. ACM, 59 (6):12-14, 2016.


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