From: paul@poboy.b17c.ingr.com (Paul Robichaux)
Date: Tue, 8 Feb 94 07:10:51 PST
To: karn@qualcomm.com (Phil Karn)
Subject: Re: STEG: a real-life use for steganography
In-Reply-To: <199402080707.XAA24919@servo.qualcomm.com>
Message-ID: <199402081509.AA17293@poboy.b17c.ingr.com>
MIME-Version: 1.0
Content-Type: text/plain


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> There's a practical problem here. Audio CD players generally provide
> no easy way to get the raw bits into a computer (SPDIF interface cards
> exist for PCs, but they're rare and expensive). And I haven't yet
> figured out how to get a CD-ROM drive to read the raw bits off an
> audio CD; I suspect it requires munging the firmware in the drive,
> which makes anything you do highly manufacturer specific.

Apple's CD-300/300i drives can read audio bits directly and turn them
into a QuickTime sound channel, as can SGI's SCSI CD. Apple uses a
Sony mechanism, and SGI uses a Toshiba. The SGI drives use modified
firmware and (AFAIK) are not available elsewhere, but you can get the
Apple drives at Circuit City, Sears, etc.

With the right sequence of SCSI commands you could easily capture an
"audio" bitstream, then munge it as desired to extract the stegged
data, play it backwards, or whatever. IIR, code to directly read
arbitrary audio data on an Apple CD-ROM was recently posted in
comp.sys.mac.programmer, but I didn't save it.

- -Paul

- -- 
Paul Robichaux, KD4JZG     | "Though we live in trying times 
perobich@ingr.com          |  We're the ones who have to try." - Neil Peart
Intergraph Federal Systems | Be a cryptography user- ask me how.
	       Of course I don't speak for Intergraph.

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