From: "Alex F" <alexf@iss.net>
Date: Thu, 25 Jul 1996 04:57:38 +0800
To: tcmay@got.net (Timothy C. May)
Subject: Re: Digital Watermarks for copy protection in recent Billbo
Message-ID: <199607241653.MAA22114@phoenix.iss.net>
MIME-Version: 1.0
Content-Type: text/plain



> >Yes, but concievably if (whoever would be incharge, FBI?) *could*,
> >under law do this, even if they are wrong.  It is a lot harder to
> >prove that they intentionally harrassed *you* than it is for them to
> >say that they were following leads and show evidence.  Yes, this may
> 
> To go to trial, an indictment would be needed. How likely is this?

The likelyness is irrelevant to the point.  Possibility is relevant.  
Probability is not.

> Discussion of "in theory they could arrest you" points often neglects the
> realities of the legal system.

Does that really matter? .  In REALITY, it 
will never be enforced.  So what?  The potential is still there, and 
in essence, that is ALL that matters!  The discussion of "in 
theory...." doesn't neglect the realities of the legal system, rather 
it highlights the POTENTIAL for abuse.  Even if the law is never 
enforced, could it not be used as an example to justify other laws 
that *may* be introduced?  Does it not set a dangerous precedent?    We 
are talking about dangerous empowerment  here.

Hmm. The arguement "well, we would never REALLY enforce it" just 
doesn't hold water with me, and makes me uncomfortable.

> A large fraction of pawnshop items have questionable provenance, the items
> having been stolen at some time in the past. Could J. Random Buyer who
> walks in, sees an item he likes, buys it, and walks out with it be
> handcuffed and taken down the lockup for the crime of buying stolen
> property? Doubtful, in the real world. And defense would be ridicuously
> easy.

A defense would be easy, fine.  But it would still cost $$$.  Do you 
see what I am getting at?  This is done ALL THE TIME (no, not at pawn 
brokers.  I'm talking about taking advantage of either cost or time 
to get what you want).


> A trivial increase in frequency, and still not allowing the hypothesized 30
> KHz signal to be added. DATs often sample at 44 and 48 KHz, switchably. The
> CD standard is of course still what it is.

That's not the point.  What we are talking about here is a covert 
channel.  Whether it is at 30KHZ, 22KHz or right in the middle of the 
audible range.  Mine was ONE proposal, a theory of sorts, thought up 
off of the top of my head as a possible way of doing this.  

You can also add a digital serial number right in the audible range, if 
you like.  Static that is recorded along with analog sound is at certain 
frequency ranges, typically.  When you have a disk that holds 640Mb 
or so the serial number's size is trivial in comparison.  Sending the 
whole number at once will barely be audible even if in a good 
frequency range simply because of speed.  If you send it in bits and 
pieces during the song, and furthermore record this data in the 
middle of the frequency range where static is located, you won't hear 
it anyway.  However certain devices will be able to read the data w/o 
problem.

Similarly, you have a CD, let's say Beethoven's 9th symphony.  You 
have ~640 MB on the CD.  If you want to sneak someone an encrypted 
message, say a top secret document and it is compressed down to 1K, 
then putting this into the audio signal as described above is fairly 
trivial.  The other end doesn't even need to know bit counts.  The 
document can be spreadout, reversed, whatever and just signaled w/ a 
flag (much like PPP and other protocols).  All the other end needs to 
decode is a flag at a set frequency range, both of which can be constantly 
changed. 

interestingly,

Alex F
=-=-=-=-=-=-=-=-=-=-=-=-=-
Alex F    alexf@iss.net
Marketing Specialist
Internet Security Systems
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