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

Ben Laurie ben at algroup.co.uk
Fri Oct 19 07:08:30 EDT 2001


Marc Branchaud wrote:
> 
> 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.

Although I agree with the general point, I should just mention that if
an SSL break is a break of a private key, then future communications
between the broken party and others may be compromised.

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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