Graphic encryption

[Patrick Horgan]

> From: Andrew Loewenstern <andrew_loewenstern at il.us.swissbank.com>
> 
> >  Is there anything particular in graphic encryption? I usually
> >  encrypt graphics and document images as regular files with regular
> >  encryption...
> 
> I believe graphic encryption outputs a valid image file that is apparently  
> white noise until you perform the decryption transformation on it.  An  
> obvious way to do this with a non-lossy file format is to encrypt pixel vales  
> with a stream cipher.  Another way to make the image unviewable would be to  
> shuffle the pixels or rasters with a PRNG.
> 

I thought it was the ideas presented in Dr Dobbs last year of encoding other
information in a graphic image so that the image still looked the same, but
the other information could be extracted...i.e. using the image as a covert
channel.  Does anyone know what they're really talking about?

Patrick
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