[9663] in cryptography@c2.net mail archive
Re: limits of watermarking (Re: First Steganographic Image in the Wild)
daemon@ATHENA.MIT.EDU (Ben Laurie)
Wed Oct 17 10:41:37 2001
Message-ID: <3BCD4BA1.1F5CE147@algroup.co.uk>
Date: Wed, 17 Oct 2001 10:13:05 +0100
From: Ben Laurie <ben@algroup.co.uk>
MIME-Version: 1.0
To: Adam Back <adam@cypherspace.org>
Cc: Greg Broiles <gbroiles@well.com>,
cryptography <cryptography@wasabisystems.com>
Content-Type: text/plain; charset=us-ascii
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Adam Back wrote:
> Another framework is to have players which will only play content with
> certified copy marks (no need for them to be visible -- they could be
> encoded in a logo in the corner of the screen). The copymark is a
> signed hash of the content and the identity of the purchaser.
>
> This could be relatively robust, except that usually there is also a
> provision for non-certified content -- home movies etc -- and then the
> copy mark can be removed while still playing by converting the content
> into the home movie format, which won't and can't be certified.
The other obvious weakness in such a scheme is that the player can be
modified to ignore the result of the check - rather like defeating
dongles, which have yet to exhibit any noticable resistance to crackers.
Cheers,
Ben.
--
http://www.apache-ssl.org/ben.html
"There is no limit to what a man can do or how far he can go if he
doesn't mind who gets the credit." - Robert Woodruff
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