From: Derek Upham <upham@cs.ubc.ca>
Date: Thu, 6 May 93 13:57:15 PDT
To: cypherpunks@toad.com
Subject: HIDE: Alpha version of JFIF steganography available
Message-ID: <199305062057.AA00672@grolsch.cs.ubc.ca>
MIME-Version: 1.0
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I've got a working version of a JPEG steganograpy program.  It uses
modified cjpeg/djpeg sources to stick arbitrary files in JPEG images
and then extract them.  It needs testing.

The files are in ftp.cs.ubc.ca:pub/pickup/jsteg.  There is a copy of
the JPEG-v4 sources (or use your own), a context-diff of the source
changes (use "patch -p0" in the directory above the sources), and a
test ".jpg" file.  Assuming everything works correctly, running

  djpeg -crypt filetoread.txt miyazaki.jpg > /dev/null

will extract the steganized text into the file "testout.txt" and dump
the PPM file.  (The extracted text should be an exact copy of the
"USING" file in the JPEG-v4 distribution.)  To steganize a file, use

  cjpeg -crypt filetohide.txt image.ppm > image.jpg

or replace "image.ppm" with "-G image.gif", etc.  If "cjpeg" reports
that it's unable to inject the file, compress the file or use a higher
"-Q" parameter.  In general, the stegfile needs a final JPEG file
that's at least eight times larger.

Derek

"Naaaaaaaaaaah, Quess isn't stupid.  A vicious, vindictive, underhanded, slimy,
double-crossing, self-deluding, daddy-hunting, family-killing, conscienceless,
callous, sexually repressed, Electra Complex victimized, self-interested, snot-
ty, obnoxious little preadolescent whining B*T*H, yes.  But she's not stupid."