Re: [RFC PATCH 0/5] CPU Jitter RNG

From: Stephan Mueller
Date: Tue Feb 04 2014 - 15:25:42 EST


Am Dienstag, 4. Februar 2014, 12:08:23 schrieb Theodore Ts'o:

Hi Theodore,

>
>> [2] http://www.chronox.de/jent/doc/CPU-Jitter-NPTRNG.html
>
>which don't really add much to the discussion, but instead just simply
>make an expert question how deep the analysis has gone. Measuring the
>statistical tests of the entropy pool is a complete waste of time ---
>and in general, using things like "dieharder" don't do anything to
>increase one's confidence (and could decrease one's confidence if it
>makes it appear too much like a snake oil sales document). Sure,
>passing dieharder is necessary, but it isn't even vaguely close to
>sufficient.
>

I am a bit surprised by this statement because I use statistical test
only as a necessary baseline. After that, the hard work started on the
actual noise source by measuring the actual noise coming out of the
noise sources. All of these tests have nothing to do with the
statistical tests of dieharder & Co.

That is the sole reason why I looked into testing the timing variations
on bare metal, independently for each noise source. Also, measuring the
basic noise on a large array of different CPUs which then show similar
behaviors are used to help my case.

So, when only looking at the statistical tests, the majority of the work
is not considered.

Ciao
Stephan
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