Steganography encoder/decoder written in C

What is setganography?

Steganography is a way to encode or hide messages/files (information) within another message or media in a concealed manner.

How does it work?

In this program, the encoding uses a method of changing the Least Significant Bit (LSB) of the Red, Green and Blue (RGB) channel on an image. The least significant bit is the bit position in a binary integer giving the units value, usualy in the 1's position.

For example, from binary 12 (00001100) to binary 13 (00001101)

00001100 <-
Least significant bit

Changing the LSB slightly alters the color value — but this tiny change is visually undetectable to the human eye without utilizing special software. This is what makes steganography possible. For a better in-depth explination pelase watch Chris Tralie's video on a Python based steganography encoder here: https://www.youtube.com/watch?v=kkmpP_7mY_I

Compiling

Linux

Make sure you have gcc or other C/C++ compiling programs installed. gcc can be installled on Ubuntu Linux by running: sudo apt install gcc

One line clone & compile.

git clone https://github.com/Roomy6/C-Steganography.git && cd C-Steganography/ && ./build.sh

Usage

Using lossy image encoding such as .jpg will not work for decoding, it is recommended to use .png or .bmp formats instead. However, the program does support converting .jpg to .png

Running ./steg will display the programs arguments as such:

Usage:
  Encode: ./steg encode <input_image> <output_image> <text|file> <payload>
  Decode: ./steg decode <input_image> <output_file> <text|file>

Example text encoding usage:

./steg encode inputImg.png encodedImg.png text "Hello, World!"

Example binary encoding usage:

./steg encode inputImg.png encodedImg.png file binary.exe

Example text decoding usage:

./steg decode encodedImg.png text outputText

Example binary decoding usage:

./steg decode encodedImg.png binaryOut.exe file

TODO

• Binary encoding placement randomization (Based on hash?)
• Text decoding outputs to file
• Change data pixel brightness
• Additional arguments
• Additional data encryption
• Encode file name
• Option to to encode both text and binary files

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Resources Used:

https://www.youtube.com/watch?v=kkmpP_7mY_I

https://solarianprogrammer.com/2019/06/10/c-programming-reading-writing-images-stb_image-libraries/

https://github.com/nothings/stb