lkml.org 
[lkml]   [2002]   [Dec]   [28]   [last100]   RSS Feed
Views: [more markup]   [less markup]   [headers]   [forward]  
 
Messages in this thread
/
FromJohn Bradford <>
SubjectRe: Want a random entropy source?
DateSat, 28 Dec 2002 20:39:16 +0000 (GMT)
> > 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.
> JB> How can you guarantee that you are sampling noise, though, what if a
> JB> sound card was picking up 50 Hz mains hum, for example,  that would
> JB> de-randomise the data quite a bit.
> 
> Well, the 50hz from the mains isn't a perfect 50hz; it has random (yes)
> fluctuations.

Yes, that's true.

More generally, though, is there any point in this going in to the
mainline kernel, if:

* Most users don't need faster entropy generation than we've got

and

* The entropy gathered from the soundcard is statistically inferior to
that gathered from the current sources of entropy.

I don't see how it's possible to guarantee that the data below a
certain dB level from the soundcard is noise.

John.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:31    [W:0.178 / U:0.140 seconds]
©2003-2008 Jasper Spaans