Image Steganography using LSB Encoding and Decoding

Overview

This project implements image steganography in C using the Least Significant Bit (LSB) technique. It allows users to securely hide a text file inside a BMP image and later retrieve the hidden data without visibly altering the image.

Features

• Encode secret text into BMP images
• Decode hidden text from encoded images
• Command-line based operation
• Preserves original image appearance
• Supports file-based secret messages

Technologies Used

• Advanced C
• File Handling
• Bitwise Operations
• Pointers
• Command Line Arguments
• Makefiles

Project Structure

• encode.c : Encoding functionality
• decode.c : Decoding functionality
• common.h : Shared declarations
• encode.h : Encoding function prototypes
• decode.h : Decoding function prototypes
• types.h : User-defined data types

How to Build

make

How to Run

Encoding

./a.out -e beautiful.bmp secret.txt stego.bmp

Decoding

./a.out -d stego.bmp output.txt

Learning Outcomes

• Understanding BMP file structure
• Bitwise manipulation techniques
• File I/O operations in C
• Command-line argument processing

Author

Nikhil Rajshekar Chavan