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"The breakthrough came when we started thinking about the components in the system as malicious actors colluding via covert channels." That's probably the piec

• cperciva 12y ago
  That's exactly the thinking which led me to the first published cryptographic side channel attack against hyperthreading: Intel's optimization manual had a comment about being careful with stack alignment to avoid poor cache performance, and I thought "what if slow could instead be maliciously slow?"
• jerf 12y ago
  This is definitely one of the most powerful debugging techniques for hard problems in my toolkit, though I phrase it as "If I wanted to produce this problem on purpose, how would I go about doing it?", since that is a general debugging technique and their phrasing is specific to communicating actors. This results in me exclaiming every 4-6 months or so that I wouldn't know how to create this particular bug on purpose if I wanted to, which I suppose doesn't make much sense as a complaint about a bug until you start thinking this way. Anyhow, it isn't perfect and you will sometimes be defeated by the sheer perversity of bugs and their behavior. (I also find these are the tiny ones, like OR instead of XOR or something equally simple and at times even one-character, that produce mind-blowing behavior off that one error. The architectural bugs tend to give way to this analysis much more readily.) But it's a useful tool much of the time.