From: Andrew Loewenstern <andrew_loewenstern@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 _______________________________________________________________________ / These opinions are mine, and not Verity's (except by coincidence;). \ | (\ | | Patrick J. Horgan Verity Inc. \\ Have | | patrick@verity.com 1550 Plymouth Street \\ _ Sword | | Phone : (415)960-7600 Mountain View \\/ Will | | FAX : (415)960-7750 California 94303 _/\\ Travel | \___________________________________________________________\)__________/