Re: hacksdmi?

[Ralph Moonen <ralph () TINK ORG>]

At 09:50 12-10-00 -0500, aliver vilereal wrote:
> From: "Ralph Moonen" <<mailto:ralph () TINK ORG>ralph () TINK ORG>
>
> -------------------------
> > This is not true per se. Might be true for *this* algo, but the guys 'n
> > galls at the Fraunhofer institute have figured a way to put in digital
> > watermarks that:
> > -survives heavy compression
> > -survives many sequences of D/A - A/D conversion
> > -survives all kinds of effects(!!)
> > -survives even in short samples of the music
> >
> --------------------------
>  But eventully the
> watermark will be broken, and when it is, it is only a matter of piecing it
> back together to find the key to cracking it.  This is true no matter what
> algroithm is used to mark it, even the very complex one listed below (from
> Ralph's post).

Maybe it is possible to cryptographically hash the watermark in such a way
that the time needed to crack it would exceed the average product lifetime
of the
media-players involved. This would be a very effective copy protect mechanism.



> And here is a question for the list:
> If the watermark is hidden in the least significant bits, a program could
> set all these bits to zero and this should effectively disable the
> watermark, because I am guessing that to compute the watermark an _exact_
> match must be made with the output of some decoding algorithm.

In this case a moot point since just flipping bits is NOT the way they did
it, and
is just about as brain-dead as adding noise to the signal.
SDMI does NOT operate by flipping LSB's. I have no idea how it does work.

--RAlph