gpg avc

[Russell Coker]

On Thu, 22 Apr 2004 00:40, Valdis.Kletnieks at vt.edu wrote:
> I think the basic concept there is that even without a microphone, as you
> sample, most cards won't return a steady stream of exact zeros - you'll get
> back the tiniest bit of background hiss, and the low-order bits have
> entropy.
>
> Of course, doing this without filtering is a Bad Idea - the amount of
> entropy coming off the always-on cheap sound card in my laptop that has
> maybe 70db S/N is probably a lot higher than somebody who has a high-end
> card that has 85db S/N - and if their card supports auto-muting for unused
> inputs, you're basically screwed...

Detecting an auto-mute input should be quite easy, just read for a second or 
two and see if there is any change in the signal.  Also writing non-random 
data to /dev/random is supposed to not cause any problems.

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