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Re: really undetectable crypto

On Thu, 12 Sep 96 19:26:56 -0700, Jim Miller wrote:

>Most everybody on the list is familiar with the technique of hiding  
>encrypted messages in the LSBs of image files.  Personally, I would not  
>use such a technique because don't I believe it's really undetectable.  I  
>assume, without proof, that the LSBs of images files have statistical  
>properties that are sufficiently different from encrypted data that a  
>clever person could determine whether or not an image file contained an  
>imbedded encrypted message.

Actually, if you use only a few bits - and not, say, bit 15 of *every* pixel -
you can feel secure *IF* you are writing truly encrypted data.  A regular PGP
message has a bunch of header material that most certainly is not
random-looking.  OTOH, if you only write the raw data, then there is no way to
differentiate from the random noise added by any scanner - in most cases, the
last couple bits in each RGB triplet of a truecolor image are random.

# Chris Adams <[email protected]> | http://www.io-online.com/adamsc/adamsc.htp
# [email protected] | V.M. (619)515-4894
"I have never been able to figure out why anyone would want to play games on
a computer in any case when the whole system is a game.  Word processing,
spreadsheets, telecoms -- it's all a game.  And they pay you to play it."
	-- Duncan Frissell