Re: x86 MSRs - example program

Matthias Urlichs (smurf@noris.de)
5 Mar 1997 15:27:46 +0100


In linux.dev.kernel, article <m0w1e9H-000AA6C@cerebro>,
mlehmann@hildesheim.sgh-net.de (Marc Lehmann) writes:
> >> ON the other hand... security hole????? how????????
> >>
> >Cryptography. If you know exactly how long a given algorithm takes for
> >different inputs, you can sometimes infer clues about the secret key.
>
> gettimeofyday is always available, and in that scenario is just
> as good as rdtsc.
>
gettimeofday isn't nearly as accurate. While that's not an absolute
barrier, it raises the number of iterations required to get accurate data.

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