Want a random entropy source?

Stephen Satchell (list@fluent2.pyramid.net)
Sat, 28 Dec 2002 07:40:29 -0800


Not too long ago I had made a submission on SlashDot on something-or-other
(oh, right, "Rube-Goldberg Type Random Number Generators?"
http://ask.slashdot.org/article.pl?sid=02/07/26/1751228&tid=137) and I
stumbled across my submission to that article. After thinking about it, I
though it might be a reasonable thing to submit to this list as a possible
enhancement to the /dev/random driver if someone wants to try it. My
submission was thus:

"I've been vexed that the sound card plus CD-ROM drive combination always
shows signal at around -50 dBVU in CoolEdit. So, just for grins, I decided
to capture a few seconds of the noise and analyze the properties. I was
astonished to see that the resulting signal is a white-noise pattern with a
slight emphasis at the high end (when sampled at 44 kilosamples per
second). In short, it looks like diode noise with a 4 kilohertz square wave
thrown in.

"That suggests to me that this would make a fair source of random samples,
especially after you slot out the interfering signal.

"How many computers don't have cheap sound cards and CD-ROM drives?"

For what it's worth...

Satch

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