From: grendel@netaxs.com (Michael Brandt Handler)
Date: Thu, 28 Apr 94 18:42:35 PDT
To: cypherpunks@toad.com (Cypherpunks)
Subject: Random #'s via CD-ROM?
Message-ID: <199404290142.VAA04213@access.netaxs.com>
MIME-Version: 1.0
Content-Type: text


Hello cypherpunks (first post):

	In the hopes of starting an cryptograpy-related thread...


	I have been reading the section in _Applied Cryptography_ about
random number generators, and some proposed hardware random number
generators. It seems to me that with the CD-ROM drive becoming
increasingly common these days, this could be exploited as a source of
randomness. For example:

	[1] Read a pseudo-random section from the CD-ROM. Unless you catch
the blank end of a sector, you should obtain random data (this is one
obvious problem with this method).

	[2] Read a pseudo-random section from the CD-ROM, and use this
data to select another chunk of data from the CD-ROM (more random, yet we
still have a problem if we read the blank end of a sector...).

	The two above ideas are okay, but they both suffer from the same
problem, namely if you read the unused portions of the cluster you will
get a random sample of all 0's. Not good.

	The idea that really interests me is this:

	Place an *audio* CD in the CD-ROM drive. Most CD-ROM drives know
about audio discs now, and I believe they can be made to read the binary
waveform data even if they don't understand the Red Book audio format. If
you have something really random/discordant (Ministry / NIN / Curve /
Sonic Youth / Pain Teens / Diamanda Galas / Coil / etc) and you take
samples of the waveform and play with them as described in _AC_, you could
get some pretty random samples.

	Of course, care must be taken to only read within the portions of
the CD/CD-ROM that have actually been encoded....

	What do you all think? I have code to work with CD-ROM drives,
works on my system and a friend's CD-ROM drive as well (for DOS machines).
I don't know about Mac / UNIX CD-ROM drive programming, sorry. =(

	I welcome all comments, criticisms, flames, love letters, etc.
Post if there's wide enough appeal, or just email me.

	[ I am also taking suggestions for random / discordant / loud
music to use with this method. Please email me, don't post, as I'm sure
the rest of the list would dislike us discussing that in public ]

-- 
==========================================================================
| Michael Brandt Handler   |  <grendel@netaxs.com>  |   Philadelphia, PA |
==========================================================================