[690] in cryptography@c2.net mail archive
Re: Random numbers from the '60's...
daemon@ATHENA.MIT.EDU (Perry E. Metzger)
Mon May 5 20:12:20 1997
To: Phil Karn <karn@qualcomm.com>
cc: brettc@tritro.com.au, stewarts@ix.netcom.com, cryptography@c2.net
In-reply-to: Your message of "Mon, 05 May 1997 16:23:42 PDT."
<199705052323.QAA26786@servo.qualcomm.com>
Reply-To: perry@piermont.com
Date: Mon, 05 May 1997 19:37:31 -0400
From: "Perry E. Metzger" <perry@piermont.com>
Phil Karn writes:
> >I'm pretty sure that what Phil is referring to is using the noise
> >generated by the preamp without a microphone connected. As far as I'm
> >aware this is similar to shot noise in resistors which generates pretty
> >nice random bit sequences.
>
> Right, though having a microphone attached certainly won't hurt. My
> point was simply that a microphone isn't *essential*, as it's been my
> experience that the microphone preamp on a typical soundblaster card
> is quite noisy. Just crank the gain all the way up and hash the resulting
> noise. If you do have a microphone connected, so much the better. Just
> make sure the speaker is muted to avoid some annoying screeches.
I'm not sure that I trust this, if only because much of the "noise"
might not be thermal noise but instead things like the board picking
up stuff from the rest of the machine, most of which is decidedly
non-random...
Perry
