limits of watermarking (Re: First Steganographic Image in the Wild)

[Ben Laurie]

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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