Cryptosteganography

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A python steganography module to store messages or files protected with AES-256 encryption inside an image.

Steganography is the art of concealing information within different types of media objects such as images or audio files, in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message. By default steganography is a type of security through obscurity.

Additionally this module also enhance the security of the steganography through data encryption. The data concealed is encrypted using AES 256 encryption, a popular algorithm used in symmetric key cryptography.

Prerequisites

Python 3+ <https://www.python.org/downloads>_

pip3 <https://pip.pypa.io/en/stable>_

(Most Linux systems comes with python 3 installed by default).

Dependencies Installation (Ubuntu)

.. code:: bash

$ sudo apt-get install python3-pip

Dependencies Installation (MacOS)

To install Python3 I recommend use Homebrew package manager

The script will explain what changes it will make and prompt you before the installation begins.

.. code:: bash

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Edit your ~/.profile to include (if it is not already there)

.. code:: bash

export PATH=/usr/local/bin:/usr/local/sbin:$PATH

To install Python 3:

.. code:: bash

$ brew install python3

Installation

To install the package just run

.. code:: bash

$ pip3 install cryptosteganography

Usage

Use as a library in a python program ''''''''''''''''''''''''''''''''''''

Store a message string inside an image

.. code:: python

from cryptosteganography import CryptoSteganography

crypto_steganography = CryptoSteganography('My secret password key')

# Save the encrypted file inside the image
crypto_steganography.hide('input_image_name.jpg', 'output_image_file.png', 'My secret message')

secret = crypto_steganography.retrieve('output_image_file.png')

print(secret)
# My secret message

Store a binary file inside an image

Note: This only works if the concealed file size is smaller than the input image

.. code:: python

from cryptosteganography import CryptoSteganography

message = None
with open('sample.mp3', "rb") as f:
    message = f.read()

crypto_steganography = CryptoSteganography('My secret password key')

# Save the encrypted file inside the image
crypto_steganography.hide('input_image_name.jpg', 'output_image_file.png', message)

# Retrieve the file ( the previous crypto_steganography instance could be used but I instantiate a brand new object
# with the same password key just to demonstrate that can it can be used to decrypt)
crypto_steganography = CryptoSteganography('My secret password key')
decrypted_bin = crypto_steganography.retrieve('output_image_file.png')

# Save the data to a new file
with open('decrypted_sample.mp3', 'wb') as f:
    f.write(secret_bin)

Use as a python program '''''''''''''''''''''''

Check help at command line prompt to learn how to use it.

.. code:: bash

$ cryptosteganography -h
usage: cryptosteganography [-h] {save,retrieve} ...

A python steganography script that save/retrieve a text/file (AES 256
encrypted) inside an image.

positional arguments:
  {save,retrieve}  sub-command help
    save           save help
    retrieve       retrieve help

optional arguments:
  -h, --help       show this help message and exit

Save sub command help

.. code:: bash

$ cryptosteganography save -h
usage: cryptosteganography save [-h] -i INPUT_IMAGE_FILE
                              (-m MESSAGE | -f MESSAGE_FILE) -o
                              OUTPUT_IMAGE_FILE

optional arguments:
  -h, --help            show this help message and exit
  -i INPUT_IMAGE_FILE, --input INPUT_IMAGE_FILE
                        Input image file.
  -m MESSAGE, --message MESSAGE
                        Your secret message to hide (non binary).
  -f MESSAGE_FILE, --file MESSAGE_FILE
                        Your secret to hide (Text or any binary file).
  -o OUTPUT_IMAGE_FILE, --output OUTPUT_IMAGE_FILE
                        Output image containing the secret.

Retrieve sub command help

.. code:: bash

$ cryptosteganography retrieve -h
usage: cryptosteganography retrieve [-h] -i INPUT_IMAGE_FILE [-o RETRIEVED_FILE]

optional arguments:
  -h, --help            show this help message and exit
  -i INPUT_IMAGE_FILE, --input INPUT_IMAGE_FILE
                        Input image file.
  -o RETRIEVED_FILE, --output RETRIEVED_FILE
                        Output for the binary secret file (Text or any binary
                        file).

Save message example

.. code:: bash

$ cryptosteganography save -i 4824157.png -m "My secret message..." -o output.png
Enter the key password:
Output image output.png saved with success

Retrieve message example

.. code:: bash

$ cryptosteganography retrieve -i output.png
Enter the key password: 
My secret message...

Save file example

.. code:: bash

$ cryptosteganography save -i input_image_name.jpg -f duck_logo.pem -o output_file.png
Enter the key password:
Output image output_file.png saved with success

Retrieve file example

.. code:: bash

$ cryptosteganography retrieve -i output.png -o decrypted_file
Enter the key password: 
decrypted_file saved with success

License

This project is licensed under the MIT License - see the LICENSE <https://github.com/computationalcore/cryptosteganography/blob/master/LICENSE>_ file for details

Authors

Vin Busquet <https://github.com/computationalcore>_ file for details

Limitations

• Only works with python 3
• It does not work if the conceived file is greater than original input file
• Output image is limited to PNG format only.
• I did not tested with all conceived file types. Feel free to report <https://github.com/computationalcore/cryptosteganography/issues>_ any bug you find

Contributing

For details, check out CONTRIBUTING.md <https://github.com/computationalcore/cryptosteganography/blob/master/CONTRIBUTING.md>_.

Changelog

For details, check out CHANGELOG.md <https://github.com/computationalcore/cryptosteganography/blob/master/CHANGELOG.md>_.

Acknowledgments

• PyCryptodome <https://github.com/Legrandin/pycryptodome>_
• Stéganô <https://github.com/cedricbonhomme/Stegano>_