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https://github.com/resurrecting-open-source-projects/outguess

Universal steganographic tool
https://github.com/resurrecting-open-source-projects/outguess

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Universal steganographic tool

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README 

        
# OutGuess



#### outguess - universal steganographic tool



## What is OutGuess?



Outguess is a universal steganographic tool that allows the insertion of hidden

information into the redundant bits of data sources. The nature of the data

source is irrelevant to the core of outguess. The program relies on data

specific handlers that will extract redundant bits and write them back after

modification. Currently only the PPM (Portable Pixel Map), PNM (Portable  Any

Map), and JPEG image formats are supported, although outguess could use any

kind of data, as long as a handler were provided.



Steganography is the art and science of hiding that communication is happening.

Classical steganography systems depend on keeping the encoding system secret,

but modern steganography are detectable only if secret information is known,

e.g. a secret key. Because of their invasive nature steganography systems leave

detectable traces within a medium's characteristics. This allows an

eavesdropper to detect media that has been modified, revealing that secret

communication is taking place. Although the secrecy of the information is not

degraded, its hidden nature is revealed, defeating the main purpose of

Steganography.



For JPEG images, OutGuess preserves statistics based on frequency counts. As a

result, no known statistical test is able to detect the presence of

steganographic content. Before embedding data into an image, the OutGuess

system can determine the maximum message size that can be hidden while still

being able to maintain statistics based on frequency counts.



OutGuess uses a generic iterator object to select which bits in the data should

be modified. A seed can be used to modify the behavior of the iterator. It is

embedded in the data along with the rest of the message. By altering the seed,

OutGuess tries to find a sequence of bits that minimizes the number of changes

in the data that have to be made.



A sample output from OutGuess is as follows:



```

Reading dscf0001.jpg....

JPEG compression quality set to 75

Extracting usable bits: 40059 bits

Correctable message size: 21194 bits, 52.91%

Encoded 'snark.bz2': 14712 bits, 1839 bytes

Finding best embedding...

    0:  7467(50.6%)[50.8%], bias  8137(1.09), saved:   -13, total: 18.64%

    1:  7311(49.6%)[49.7%], bias  8079(1.11), saved:     5, total: 18.25%

    4:  7250(49.2%)[49.3%], bias  7906(1.09), saved:    13, total: 18.10%

   59:  7225(49.0%)[49.1%], bias  7889(1.09), saved:    16, total: 18.04%

59, 7225: Embedding data: 14712 in 40059

Bits embedded: 14744, changed: 7225(49.0%)[49.1%], bias: 7889, tot: 40032, skip: 25288

Foiling statistics: corrections: 2590, failed: 1, offset: 122.585494 +- 239.664983

Total bits changed: 15114 (change 7225 + bias 7889)

Storing bitmap into data...

Writing foil/dscf0001.jpg....

```



The simple example script `seek_script` uses OutGuess to select an image that

fits the data we want to hide the best, yielding the lowest number of changed

bits. Because we do not care about the actual content of the cover data we

send, this is a very viable approach.



Additionally, OutGuess allows to hide multiple messages in the data. Thus, it

also provides plausible deniability. It keeps track of the bits that have been

modified previously and locks them. A `(23,12,7)` Golay code is used for error

correction to tolerate collisions on locked bits. Artificial errors are

introduced to avoid modifying bits that have a high bias.



Currently OutGuess can insert only two different messages. This is an

experimental feature.



## Help this project ##



OutGuess needs your help. **If you are a programmer** and want to help a nice

project, this is your opportunity.



The original OutGuess went unmaintained; the source of the last version, 0.2,

was [imported from Debian](https://snapshot.debian.org/package/outguess/) or other

repositories of the Internet. After, patches from Debian and elsewhere were

applied to create the 0.2.1 release. The details of each release are registered

in the [ChangeLog](ChangeLog) file. Now, OutGuess is maintained by volunteers

under [Resurrecting Open Source

Projects](https://github.com/resurrecting-open-source-projects).



If you are interested in helping OutGuess, read the [CONTRIBUTING.md](CONTRIBUTING.md) file.



## Building



### Prepare the `jpeg-6b-steg` library



To do so, you need to choose (and potentially edit) an appropriate `jconfig.h`

file. To get an idea which one you might want, have a look at their header

comments.



You might do so like this (POSIX only):



```

head -n 1 src/jpeg-6b-steg/jconfig.*

```



The default one is `jconfig.cfg`. You may use it like this:



```

cd jpeg-6b-steg

ln -s jconfig.cfg jconfig.h

cd ..

```



However, in OutGuess 0.3 or newer, there is the option `--with-generic-jconfig`

that will use `jconfig.cfg` automatically. See the *Build and install OutGuess*

section below.



### Build and install OutGuess



OutGuess has only been tested on OpenBSD, Linux, Solaris and AIX.



If you manually edited `jconfig.h`, you must use the following command

sequence:



```

./autogen.sh

./configure

make

make install

```



Otherwise, if you prefer to use `jconfig.cfg` content as default for

`jconfig.h`, without a manual action, you can use the following sequence:



```

./autogen.sh

./configure --with-generic-jconfig

make

make install

```



## Embedded modified JPEG library



OutGuess needs a modified version of the JPEG library. Currently, the original

lib (without changes) is available at https://www.ijg.org/files/. The tarball

name for version 6b is `jpegsrc.v6b.tar.gz` (or `jpegsr6b.zip`).



There is a complete document about the JPEG in

`src/jpeg--steg/install.doc` in OutGuess source code (this is plain

text, not a traditional

*.doc*).



The .diff file used to modify the original JPEG library is available at `/doc`

in OutGuess source code.



## Acknowledgments



OutGuess uses code from the following projects.

Attributions can also be found in the sources.



* Markus Kuhn's Stirmark software,

  see [doc/STIRMARK-README](STIRMARK-README)

* the Independent JPEG Group's JPEG software,

  see [src/jpeg-6b-steg/README](src/jpeg-6b-steg/README)

* the Arc4 random number generator for OpenBSD, (C) 1996 by

  David Mazieres 

* free MD5 code by Colin Plumb



For determining the redundant bits out of a JPEG image,

the `jpeg-jsteg-v4` patches by Derek Upham  were helpful.



Special thanks to:



* Robert Morelos-Zaragoza , author of golay.c,

  that gently agreed to change its licensing to BSD.

* Dug Song  for helping with the original configure file,

* Andrew Reiter  for testing on Solaris.



## Author ##



OutGuess was originally developed by Niels Provos ,

under the BSD software license. It is completely free for any use including

commercial.



Currently, source code is maintained by volunteers. Newer versions are

available at https://github.com/resurrecting-open-source-projects/outguess