From: Brian D Williams <talon57@well.sf.ca.us>
Date: Thu, 17 Feb 94 13:35:28 PST
To: cypherpunks@toad.com
Subject: Dos Stego
Message-ID: <199402172133.NAA15322@well.sf.ca.us>
MIME-Version: 1.0
Content-Type: text/plain



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Bruce C Dovala asks:
 

   Does anyone know of a Stego program for Dos?


 Well, the only Stego program I've seen other than Mistress
Romana's for the Mac is by Black Wolf, here's the readme file;



              Black Wolf's Picture Encoder (for 320x200x256       
              ONLY!!!!)

                              Version 0.90a

                     Released into the Public Domain

                     All Code Written By Black Wolf

Disclaimer:  This program is hereby released into the public
domain.  I take no responsibilities for any damages it might cause.

Use it at your own risk.

Description:  This picture encoder consists of a group of programs
designed to let you capture a picture, encode a message in it, and
display it so that it may be captured again into another format
with a third-party program, then recapture it and decode the
message previously place inside it.  It is at a bare-bones stage
right now, and includes source code if you would like to tailor it
to your own needs.

Uses:  If you have a need to send sensitive data, but don't want it
to be obvious that that is what you are doing, this might be a good
program for you.  The sender can encode anything he/she wants into
the picture and then convert it to .GIF format, .PCX format, or
whatever (using a third part program).  Not many people will look
twice if you receive a picture, whereas an encrypted message might
raise an eyebrow or two.  Then, the receiver is free to decode it
at will.  Anything under about 8k can be recorded into one picture
- - important letters, lists, small programs (viruses), or just 
about anything else.  If you are sending text, my recommendation is
to encrypt with via PGP or some similar program, then encode it
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Ya gotta love this
guy!
into the picture for added security.

Tech:  The programs encodes data into the LSB's (least significant
bits) of the picture file - thus, roughly 50% of the colors are
changed, but if they are it is only by one pallette value (0-255). 
If the picture's pallette is based on gradients, then this will
most likely be undetectable.  Also - ENCODE will put an EOF at the
end of the message, so that while there will be garbage at the end
of the decoded message it will not be displayed if the
file is opened with edit or typed, etc....

The files are as follows:
GETSCR - Captures a picture into MESSAGE.SCR when you press
PRINTSCREEN while in graphics mode 13h (320x200x256).

PUTSCR - Puts the picture in MESSAGE.SCR onto the screen, generally

         so that it may be re-captured into another program.

ENCODE - Encodes the data in the file MESSAGE.DAT into the picture
         in MESSAGE.SCR.

DECODE - Decode the message in the picture MESSAGE.SCR and puts it 
         into NEWMESS.DAT.

Example:  Say you want to send text to someone, but you don't want
it to  "appear" that way to anyone who may intercept the message. 
First, what you'd want to do is find a picture file (like a GIF). 
Then, run GETSCR and pop the picture up into any picture viewer. 
While the picture is on the screen, hit PRINTSCREEN and GETSCR will
create a file called MESSAGE.SCR for you containing that picture. 
Then, write your message and save it as MESSAGE.DAT.  Run ENCODE -
this will take your message and encode it into the picture file. 
At this point, you need to find a third-party screen capture
program that wil work with the format that you wish to use.
Run it to make it go memory resident, then run PUTSCR and capture
the picture it puts onto the screen.  Now you can send the picture
to your friend.
     
     When he receives it, he can display it, showing that it is,
indeed, just a picture file.  When he wants to decode it, all he
has to do is run GETSCR and display the file - hitting PRINTSCREEN
while it is displayed. Then, he should run DECODE and it will
create a file called NEWMESS.DAT that includes the message you
originally put into the file.



 I can send this to anyone interested UUencoded, It's about 30k.



Brian Williams
Extropian
Cypherpatriot

"Cryptocosmology: Sufficently advanced comunication is
                  indistinguishable from noise." --Steve Witham
 
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