[Cryptech Tech] Avalanche noise test boards

[Benedikt Stockebrand]

Hi Peter and list,

Peter Gutmann <pgut001 at cs.auckland.ac.nz> writes:

> I've talked to a few commercial vendors and many of them fail one or more of
> the more rigorous tests, which is why they all postprocess the raw noise.
> That way it doesn't matter if the noise is biased in some way, as long as it's
> unpredictable it doesn't have to be white noise since the postprocessing will
> add that.

yes; well, there are ways to do this, but if we want things to be
auditable by design, that limits our choices.

> (Think of the canonical perfect RNG, a Geiger counter fed from radioactive
> decay,

Actually, even that isn't "perfect": As the radiation source decays, the
thing "slows down", at least in theory.  This could in theory even
"break" the von Neumann extractor.

> it's extremely biased since most of the time it's outputting nothing,
> but also extremely unpredictable for the events it outputs).

Well, if you know exactly how much radiation to expect, then you can set
the measurement interval (you normally test if an event happens within a
given time interval) such that there's no bias.

But that said, I've got no intention to touch anything doing with
radioactivity.  Yes, I've heard claims that you can reuse those
tritium based watch hands, or the alpha radiator from some old smoke
detector, but no, I've got no idea to get anywhere near them...


Cheers,

    Benedikt

-- 
Benedikt Stockebrand,                   Stepladder IT Training+Consulting
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