[240] in Cypherpunks
HIDE: Alpha version of JFIF steganography available
daemon@ATHENA.MIT.EDU (Derek Upham)
Thu May 6 22:42:49 1993
Date: Thu, 6 May 1993 13:57:05 -0700
From: Derek Upham <upham@cs.ubc.ca>
To: cypherpunks@toad.com
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."
