watermarking sucks (Re: stego for the censored II)

[Trei, Peter]

I realize that this is *slightly* simplistic, but comparing 2 
(preferably 3 or more) copies of the data with different 
watermark contents should quickly reveal where and what 
constitutes the watermarking.

Of course, there are methods to make this more onerous - 
MACing the watermarked data for one - but nothing a 
determined counterfeiter couldn't work around. It only 
takes one, after all.

I'm currently working my way through Schneier's 'Secrets 
and Lies'. He has one comment I like to the effect that 
trying to make data not be copyable is a task on a par 
with trying to make water not be wet.

Peter Trei

> ----------
> From: 	Adam Back[SMTP:adam at cypherspace.org]
[...]

> Of course the whole concept of watermarking is broken at all
> levels, copying can not be prevented as the content can typically
> be reencoded and lose the watermark, quality is in heavy contention
> with the ease with which the watermark can be removed.  Even 
> if it is keyed.  And ultimately content can plausibly deniably
> be stolen and all it takes is one copy.
> 
> Adam
>