From: Peter & <shipley@merde.dis.org>
Date: Thu, 11 Mar 93 22:17:57 PST
To: cypherpunks@toad.com
Subject: Re: HIDE: embedding msgs into snd & graphics
In-Reply-To: <9303112122.AA00150@netcom.netcom.com>
Message-ID: <9303120608.AA28356@merde.dis.org>
MIME-Version: 1.0
Content-Type: text/x-pgp



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>
>The GIF option I mentioned allows a widely disseminated image file to
>contain about 32 KB in just the LSBs of a 512 x 512 x 8-bit gray scale
>image. A color image could easily hold three times more (LSBs in each color
>channel). And some GIFs are much larger than 512 on a side.

IT should be trival to include date into GIFs (or most any other non-lossy
formats) using the ppmplus library.

    giftoppm Image.gif | ppmInsertData data.pgp | ppmtogif > Image2.gif

where ppmInsertData is a program that modifies the data stream using
the file data.pgp as the crypt data source 

to extract just a command simular to:

        ppmExtractData < Image2.gif > data.pgp

for sound file it would just as easy (in fact I am almost tempted to
write some demo code but I have more email to attend to :-)

                       -Pete



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