CDR: Re: stego for the censored

[Sampo A Syreeni]

On Fri, 6 Oct 2000, Tom Vogt wrote:

>> Lossy compression.
>> 
>> balance snipped, we need lossless compression, eh?
>
>nope we don't. remember that everyone said that .jpeg couldn't be used
>for stego for that same reason? then the first .jpeg-stego tools
>arrived.

The only problem with lossy compression is that it severely limits the
capacity of the covert channel. On the other hand, embedding a maximum
amount of data into a data stream and losslessly coding the result will
certainly show in the compression ratio.

Some recent work in audio watermarking has achieved speeds of a couple of
hundreds of bits per second. Of course most of those do not get through mp3
but the good thing is that these methods are for all practical purposes
inaudible. Built for realtime use with e.g. shoutcast such methods should be
capacious enough even after error correction.

There's certain irony in using copyright protection research this way, as 
well...

Sampo Syreeni <decoy at iki.fi>, aka decoy, student/math/Helsinki university