>> Comments on http://www.openssl.org/~appro/OPENSSL_instrument_bus/ are >> welcomed. > > But here, I think you're measuring the difference between two clocks that > are derived from the same oscillator. That is worrisome. It seems > possible an adversary could analyze the device and describe the jitter > mathematically even if it's too complex to show up in your FFT tests.
Just a side note. Mathematical description wouldn't inevitably render it useless. Indeed, *if* we observe manifestation of PLL jitter and *if* jitter is result of thermal fluctuations, then what harm would it make if we knew its distribution? Or by analogy. Not that I claim that they are comparable, but radioactive decay is described even mathematically and nobody questions its viability. > Where does the underlying entropy come from, and does its safety depend > on the clock distribution hierarchy of the system where this code runs? As well as if knowing of this things would give real advantage to adversary. I also want to remind that it's not a question of using it as actual source of random numbers, but as *seed* to PRNG. Once again I want to point out that I'm not claiming that I know "the Answer" :-) ______________________________________________________________________ OpenSSL Project http://www.openssl.org Development Mailing List openssl-dev@openssl.org Automated List Manager majord...@openssl.org
