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                         VERSION: 0.3


              Copyright (C) 2003 Peter Kieltyka
                        Jan 27, 2003
                    Updated: Mar 25, 2006
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Contents:

[1] What is Stash?
[2] Usage information
[3] License
[4] Misc


-- [1] What is Stash? ------------------------------------------

Stash is a basic steganography program that hides a file within a bitmap
image without disrupting the appearance of the original image. It uses a
simple algorithm that replaces the least significant bit of a random set
of bytes from the pixel data of the bitmap image with a bit of the secret
data. The bits are distributed throughout the container file (BMP) as
determined by the password supplied to seed the PRNG.


-- [2] Usage information ---------------------------------------

 Usage Examples:
   To Hide:
     ./stash "image1.bmp" "image2.bmp" "secret.txt" "hello123"
   To Extract:
     ./stash "image2.bmp" "secret.txt" "hello123"

 Tested on:
  - Windows XP
  - FreeBSD 4.7
  - Debian Linux 3.0
  - Mac OS X 10.3

 TODO:
  - Implement AES cipher to encrypt the data before hiding it
  - Add JPEG/WAV/MPG support


-- [3] License -------------------------------------------------

Stash is licensed under the BSD license. See the attached LICENSE file.


-- [4] Misc ----------------------------------------------------

code notes:
===========

  when hiding:
  a = (a & ~1) | (((b >> (7-k)) & 1) & 1);

  this takes the bit of byte 'b' at location 'k' (k goes from 0-7, 0 being the LSB)
  and stores it in the LSB of byte 'a'


  when extracting:
  a = (a & ~(1 << (7-k))) | ((b & 1) << (7-k));

  this assigns 'a' the LSB of 'b' to location 'k' (k goes from 0-7, 0 being the LSB)