[6398] in cryptography@c2.net mail archive
Blue Spike and Digital Watermarking with Giovanni
daemon@ATHENA.MIT.EDU (Eugene Leitl)
Sat Jan 15 20:53:16 2000
From: Eugene Leitl <eugene.leitl@lrz.uni-muenchen.de>
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Message-ID: <14463.50929.123629.27211@lrz.uni-muenchen.de>
Date: Fri, 14 Jan 2000 17:01:37 -0800 (PST)
To: Kevin Milani <kevin@zoetics.com>
Cc: cryptography@c2.net
In-Reply-To: <l03102800b4a44944d55e@[192.168.1.18]>
Kevin Milani writes: [Actually, I, the moderator wrote...--PM]
> [I have not heard of the product, but in general, digital watermarking
> is a pipe dream much like copy protection. Given access to several
> copies of a thing I can find the "watermarks" by comparing them. I am
This assumes the location and the amount of tweaked bits is fixed. As
long as I stay under perception threshold, and mix the watermark bits
with noise bits, using some wild steganographic/broadband encoding
thing, you need a lot of copies to recover the pristine source.
[Nope. First of all, you don't need to recover pristine source -- you
just have to destroy the watermark. Second of all, good statistical
arguments can be made for why you don't need to get that many texts
even given no knowledge of the watermark system. I'll post more if
pushed --PM]
If course in the real world either the amount of bit twiddling inserts
obvious artefacts in your multimedia stream, or the watermark can be
cleaned by twiddling the bits.
Of course you can't perceive the watermark, and know the encoding
scheme, you could flood the cargo bay with random bits.
I also haven't heard about any system which does work reliably. All I
know is that Joe Sixpack won't be able to strip the watermarks, and
hence be intimidated into not giving his buddies a few copies.
[Joe Sixpack has nothing to to lose and almost no odds of being caught
giving away two or three copies... --PM]
> unfamiliar with any systems that could actually withstand
> attack. --Perry]
