The Duty of a Scholar

On November 16th, 2004 — π years after arriving in Oxford — I submitted my doctoral thesis. My mind wasn't really on my thesis though; I was thinking about an issue I had noticed in recent Intel CPUs: The "Hyper-Threading" (simultaneous multithreading) feature they introduced in 2002 could leak information between execution threads via the cache state.

There was a joke at the time that although the National Security Agency had opened up in recent years and started taking their defensive role more seriously, the one aspect of cryptography which they would never discuss publicly was side channel attacks — and this itself constituted a side channel, revealing the importance they attributed to the field. Being active in computer security, and recognizing that the NSA knew a few things about the topic, my immediate priority was to determine whether the information leakage I had identified was sufficient to construct a practical cryptographic side channel. By mid-December I had a proof-of-concept exploit which stole enough bits of an RSA private key for the entire key to be reconstructed, and I turned my attention to the hard part of the problem: Quietly notifying security teams and working together to get the issue fixed before disclosing it publicly.