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

[Roop Mukherjee]

On Thu, 18 Oct 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.
>
> 		M.

I am not certain which scheme of copy protection you are refering to. But
I agree that any scheme that relies on a secret recipie (ala Coca Cola)
would not be effective. The analogy was intended towards publicy know
provably strong means of copy protection. Most security measures these
days would be foolish to choose otherwise. My impression of the DRM
work that was being undertaken is that most of it aiming towards "open
specifications" that are provably secure. For instance the SDMI charter
says, "...to develop open technology specifications that protect the
playing, storing, and distributing of digital music ...". Measures like
this would indeed raise the bar in much the same way as some other
security measures like SSL did.

-- Roop
________________________________________


>
>
> 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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