Cryptosteganography

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 enhances 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+ pip3 (Most Linux systems come with Python 3 installed by default).

Dependencies Installation (Ubuntu)

$ sudo apt-get install python3-pip

Dependencies Installation (MacOS)

To install Python3, I recommend using the Homebrew package manager. The script will explain what changes it will make and prompt you before the installation begins.

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

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

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

To install Python 3:

$ brew install python3

Installation

To install the package, just run:

$ pip3 install cryptosteganography

Usage

Use as a library in a Python program

Store a message string inside an image

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.

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 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 the command line prompt to learn how to use it.

$ 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

$ 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

$ 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

$ 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

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

Save file example

$ 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

$ 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 file for details.

Authors

Vin Busquet GitHub

Limitations

• Only works with Python 3.
• It does not work if the concealed file is greater than the original input file.
• Output image is limited to PNG format only.
• I did not test with all concealed file types. Feel free to report any bug you find.

Contributing

For details, check out CONTRIBUTING.md.

Changelog

For details, check out CHANGELOG.md.

Acknowledgments

• PyCryptodome
• Stéganô