limits of watermarking (Re: First Steganographic Image in theWild)

[Marc Branchaud]

This analogy doesn't quite hold.

Copy protection need only be broken once for the protection to be disabled
for a particular piece of work.  Also, once the scheme is known for one piece
of work, it is extremely easy to break the scheme for other pieces, and in
particular to write an application that will do so.

With crypto's bar-raising, OTOH, breaking one instance, like an SSL stream or
an AES key, does not break all other uses of SSL or AES.  In particular, SSL
& AES will provide the same degree of protection for any other communication
of the same data between the same or other parties.  Also, good crypto
schemes are already widely known and designed explicitly so that knowledge of
the scheme does not break the scheme.

		M.


Roop Mukherjee wrote:
> 
> The fact that someone can break open his box/software and sucessfully
> invalidate their verification scheme does not mean that there is no value in
> copy marks. Initial schemes that verify copymarks may not make it
> impossible to cheat, but they will raise the barrier. To compare, in
> theory one can break even strong encryption. We only try to make it
> "sufficiently" hard. The copy protection schemes that are being debated
> may not be as good at raising the bar as some others like SSL but the
> recording industry will push ahead because evey copyright violator
> discouraged means savings in the piracy attributed losses that their
> analysts (somewhat mysteriously) produce.



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