Been tried before?

I had an idea for a key system using graphics files. Has that been tried 
before? The basic idea was to use a graphics file with a color depth of 
24-bit or higher. Then, using the rgb values of, say, every prime pixel 
(i.e. the first pixel, then the second....then the seventh, then the 
eleventh) or something like that to create a stream of numbers the feed 
into the cipher which would be highly erratic. A similar looking picture 
would not work, as the rgb values would be (I assume) hard to guess, and 
even if you came close, you would have to get the right order. If you 
used a graphics file format similar to PNG, for instance, you could even 
include alpha channels.
    Am I just shooting my mouth off, or does this sound like something 
that would work? I'm wondering if this has been tried before and if it 
would be worth programming out.

--Drew

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At 10:25 PM 10/17/1997 PDT, Andrew Wiggin wrote:
>I had an idea for a key system using graphics files. Has that been tried 
>before? The basic idea was to use a graphics file with a color depth of 
>24-bit or higher. Then, using the rgb values of, say, every prime pixel 

What are you trying to accomplish?  Having a non-obvious place
to store passwords?  After all, your suggestion is really equivalent
to a bunch of numbers stored in a file.

What has usefully been done is to take numbers and hide them as
low-order bits in a graphic file, with various implementations
getting fancy about either just sticking them there or looking
at the palette values from the picture and finding something
visually better matching.
				Thanks!
					Bill
Bill Stewart, stewarts@ix.netcom.com
Regular Key PGP Fingerprint D454 E202 CBC8 40BF  3C85 B884 0ABE 4639