[16633] in cryptography@c2.net mail archive
Re: Cryptography Research wants piracy speed bump on HD DVDs
daemon@ATHENA.MIT.EDU (Ian G)
Wed Jan 5 11:44:55 2005
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Wed, 05 Jan 2005 15:53:22 +0000
From: Ian G <iang@systemics.com>
To: Adam Back <adam@cypherspace.org>
Cc: Taral <taral@taral.net>, Matt Crawford <crawdad@fnal.gov>,
cryptography@metzdowd.com
In-Reply-To: <20041222214755.GA2018@bitchcake.off.net>
Adam Back wrote:
>>From what I recall from reading the CR paper a while back they can
>tolerate up to some threshold of colluding players. However if you go
>over that threshold (and it's not too large) you can remove the mark.
>
>I would think the simplest canonical counter-attack would be to make a
>p2p app that compares diffs in the binary output (efficiently rsync
>style) accumulates enough bits to strip the disk watermark, p2p rips
>and publishes. QED.
>
>
If the p2p apps could collude, they could create
a pre-threshold image and share it amongst
themselves only, gradually combining it until
no more differences were detected. When a
post threshold watermark was reached, the
final image could be released. You would need
some way to know that the watermark had
been reached, according to the testing against
a sufficient sized pool or somesuch metric.
Add some reputation nyms to sign and that
should avoid the poisoning attacks as well.
--
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