CDR: Re: stego for the censored

[Bill Stewart]

There are better compression mechanisms available -
AT&T's a2bmusic compression system claimed to use about
half the bandwidth for equivalent audio quality,
by using better models of human hearing in their algorithms,
and I think SDMI and one of Sony's formats also do something like that.
The catch is that most of them also include copy protection systems,
with the attempted tradeoff of "better compression for copy protection"
and they haven't been able to overcome the popularity of MP3
(as much because of Napster as because of copy protection, I suspect.)

There are two ways to hide stego text in MP3 or JPEG.
One is before the compression - figure out the kind of sound/picture
data that will survive the compression mechanism, 
which is very hard, but more useful for watermarking.
The other is after the compression - where you have to
find methods that won't mess up the decompressed version,
which may be hard, but either you might not care about the
decompressed quality (depends on your threat model)
or there might be ways to encode stuff that's either
comment-like, so not decompressed at all, or only affects 
very small parts of the decompressed.


At 04:40 PM 10/6/00 -0400, Ray Dillinger wrote:
>On Fri, 6 Oct 2000, David Honig wrote:
>>At 10:52 AM 10/6/00 -0400, Ray Dillinger wrote:
>>>For the sake of us audiophiles, please don't.  MP3 is tinny and flat 
>>>at best;
>>
>>Then why are you 'audiophiles' traumatizing yourselves by listening
>>to it?
>
>For the most part, I'm not.  I had just hoped to have a better 
>music format available on the web, and it looks like MP3 is blocking
>it from happening.
>>We're talking about covertext, not rec.audio.cypherpunks.audiophile
>To your message recipient, it's covertext.  To everybody else 
>who downloads tunes, (since you're talking about putting stego
>in *all* MP3s downloaded from your site) it's degraded sound 
>quality.


				Thanks! 
					Bill
Bill Stewart, bill.stewart at pobox.com
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