Image Steganography

This project implements a command line utility that can be used to embed an image within another. The method used here is known as least significant bit steganography specifically using the lowest 4-bits of each color channel to embed hidden information in a container image. Be wary, this method is susceptible to noise detection techniques and so is not a particularly effective method if one's goal is to go undetected!

Below is a capture showing merged and unmerged images. On the left is the result of merging a container image with a secret image. On the right, we have the unmerged image. There's some obvious loss in quality, but the extracted image is still recognizable.

Local Builds

To build the project locally, you will need the following libraries and tools installed:

• CMake3.13+
• C++ compiler supporting C++20 features
• libpng developer libraries
• libjpeg developer libraries
• Boost version 1.76.0+

To build the project, change directory to the scripts/ directory and run build.sh (optionally pass the -g flag to build with debug symbols):

./build.sh

After a successful build, you will find the binary installed to steganography/bin/steganography.

Running with Docker

The project includes a Dockerfile that builds an image with the steganography tool installed. To build the image, run the following command from the project root directory:

docker build . -t steganography:latest

Included in the scripts/ directory is the container.sh script which launches the steganography container with a host volume mounted. The host volume can contain images to be run against the tool. Just edit the STEG_IMAGES variable to the absolute path of the directory containing your images, then navigate to /mnt/images within the container shell and run the tool as explained in the Program Usage section.

Program Usage

The steganography tool interprets three commands: help, merge, and unmerge.

The help command prints program usage info:

steganography help

The merge command takes three arguments where the first is the container image, the second is the secret image, and the final is the desired name for the merged image:

steganography merge container.jpg secret.jpg merged.png

Note The output image is ALWAYS in the PNG format. The reason is that the JPEG format uses lossy compression meaning we cannot reliably unmerge a merged image written as a JPEG.

The unmerge command takes two arguments where the first argument is an image previously constructed using the merge command and the second argument is the desired name for the unmerged image:

steganography unmerge merged.png unmerged.jpg

Only JPEG and PNG formats are supported as output formats.