Re: Digital Watermarks for copy protection in recent Billboard

["Alex F" <alexf@iss.net>]

> Paged through a recent (June or July 13) edition of Billboard 
> magazine yesterday.  There was an article about the music industry, 
> the internet, and copyright issues.  Didn't have a chance to read in 
> thoroughly, but it mentioned using digital watermarks which contained 
> info on to who (CC number) and when the material was sold... the
> watermarks allgedly could survive if a CD was taped, copied several times
> and redigitized.
> 

Easy enough.

> The anti-piracy scheme is only useful for direct sale to a customer 
> though.  If you buy music anonymously, how is it traced?  This only 
> works for pirating on-demand purchases.

This is probably yet another case of people not thinking ahead.  As 
usual.  People buying CDs at a garage sale & getting arrested for 
piracy.  Wonderful.

> 
> Other issues: what if an eavesdropper steals the music or video? It's 

If they steal it, well, who cares?  If there is something worked out 
so that they could trace STOLEN (not traded or sold) CDs then fine, 
arrest them.  Do you really think though that anyone would waste so 
much time over $8?

> If it uses a credit-card number as (part of) an ID, that's pretty 
> bad.  Someone can sniff for CC numbers if they know how it's stored.

Probably not done that way.  My guess is that the disk ID is assigned 
to the disk at the time of manufacturing.  At the point of purchase 
the customer is forced to give name, address, ID, whatever.  This is 
then stored in a database along with the disc ID (serial num) which 
is prolly printed in the ISBN number or cross referenced with that in 
a national database or something, or just printed right on the disc.  
Anyway, a number is given to you from the CD, and not vice versa, I 
would imagine.

> 
> The system will have to rely on proprietary tech and security through 
> obscurity.  Even know how watermarks are stored without understanding 
> the math, one must be able to somehow garble the sound without 
> distorting it, but which renders the watermark useless.

Actually, this would be quite easy.  The "watermark" would be a 
signal that plays inband, but out of our hearing range during the 
entire CD.  The human ear can only hear in the 20-20,000 (Hz, KHZ?, 
whatever) range.  It would be trivial to add a digital ID signal at, 
say 30,000 or 15 or something like that.  This could then be decoded, 
if need be.  This seems the easiest and most efficient way.  This 
could also be defeated with a lot of $$ (and/or a LOT of HD space).  
If the frequecy is known (it can be found out) it can easily be run 
through recording studio eqipment that can very effectively isolate 
the frequency and cut it out.  If you have a LOT of HDD space 
(digital audio at 2 stereo tracks, not sure of the sampling rate or 
bit resolution, takes about 20MB of HDD space per minute (2 tracks, 
good sampling and bit rate) ) you could probably find the freq. 
fairly easily by isolation and just edit it out, and write the new 
stuff to a CD-R.  If the signal is purely digital, I would imagine 
that it might be even easier that if it were an analog signal (?).  
Someone w/ good equipment (Digital Labs' stuff, or SAW (Software 
Audio Workshop) would be able to do this w/o much problem.  The 
question is is the price/effort worth it?  In quantity maybe.  On an 
individual basis, only if you already happen to have the erquipment.

I have a suspiscion that this type of thing will not really come to 
any kind of fruition due to not only the ability to defeat this, but 
mainly due to things like buying at a garage sale, etc.  If it did, 
only MASS market piraters would be investigated.  (Another example of 
a law creating it's own violators.  Don't make the law, there won't 
be mass piratingof "clean CDs"

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