Messages in this thread | | | Date | Tue, 27 Jul 2004 12:10:40 +0200 | From | Marc Ballarin <> | Subject | Re: [PATCH] Delete cryptoloop |
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On Tue, 27 Jul 2004 01:40:47 -0700 Junio C Hamano <junkio@cox.net> wrote:
> > Jari's exploit uses the property that his watermarks are > encrypted to identical ciphertext blocks, but does it mean that > the technique can be used to prove that identical ciphertext are > from the watermarks and not coming from mere coincidence? >
You can't prove anything by a single found watermark, but you can encode additional information by placing the watermarks at chosen offsets in your file.
For example, take prime numbers starting at 2 as offsets, and place the encodings in a chosen order at those offsets.
The chances for a random occurence of this pattern are marginal, and - unless the watermarked file becomes strongly fragmented - this pattern is easy to retrieve.
While this might not be evidence in the legal sense (it could well be, but IANAL), it is at the very least a strong indication.
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