🔐 StegaCrypt — Hide Secrets in Plain Sight

A Steganography Tool that hides secret messages inside ordinary images using LSB (Least Significant Bit) Encoding. The image looks completely normal — but it carries a hidden message inside its pixels.

🌐 Live Demo → stegacrypt.vercel.app

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🤔 What is Steganography?

Steganography is the practice of hiding secret information inside ordinary-looking data. Unlike encryption (which scrambles data), steganography makes the message invisible. The encoded image looks identical to the original — the color changes by at most ±1 per pixel, which is completely undetectable to the human eye.

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🎯 How It Works

Step	What Happens
1️⃣	Your secret message is converted to binary (0s and 1s)
2️⃣	Each pixel's RGB values are read as 8-bit binary numbers
3️⃣	The Least Significant Bit of each color channel is replaced with a message bit
4️⃣	The modified image is saved — it looks identical but carries your secret

Original pixel:  R = 11010110 (214)   G = 10110001 (177)   B = 01001110 (78)
Message bits:    0, 1, 0
Modified pixel:  R = 11010110 (214)   G = 10110001 (177)   B = 01001110 (78)
                         ↑ LSB                ↑ LSB                ↑ LSB

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🛠️ Core Java Concepts Used

This project demonstrates 12 Core Java concepts:

Concept	Implementation
OOP	Classes, Objects — StegoImage, SecretMessage, LSBSteganography
Abstraction	SteganographyEngine interface
Polymorphism	SteganographyEngine engine = new LSBSteganography()
Encapsulation	Private fields, public getters/setters
Inheritance	StegoException extends Exception
Bit Manipulation	AND (&), OR (|), SHIFT (>>, <<) operators
File I/O	ImageIO.read(), ImageIO.write(), BufferedImage
Collections	ArrayList, HashMap for pixel data and stats
Exception Handling	Custom StegoException with error type Enum
Multithreading	SwingWorker for background encoding/decoding
Swing GUI	JFrame, JPanel, JTabbedPane, JFileChooser, event listeners
Enums	ErrorType enum for categorizing exceptions

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📁 Project Structure

StegaCrypt/
├── java/                              # Core Java PBL Code
│   └── src/stegacrypt/
│       ├── Main.java                  # Entry point
│       ├── model/
│       │   ├── StegoImage.java        # Image model
│       │   └── SecretMessage.java     # Message model
│       ├── core/
│       │   ├── SteganographyEngine.java  # Interface (Abstraction)
│       │   ├── LSBSteganography.java     # Algorithm (Polymorphism)
│       │   └── StegoException.java       # Custom Exception
│       ├── util/
│       │   ├── BitManipulator.java    # Bit operations
│       │   └── ImageProcessor.java    # File I/O
│       └── gui/
│           └── StegaCryptGUI.java     # Swing GUI
│
├── web/                               # Web Demo (deployed on Vercel)
│   ├── index.html
│   ├── style.css
│   └── app.js
│
└── README.md

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🚀 How to Run

Java (Desktop GUI)

cd java
javac -d out src/stegacrypt/util/*.java src/stegacrypt/core/*.java \
      src/stegacrypt/model/*.java src/stegacrypt/gui/*.java src/stegacrypt/Main.java
java -cp out stegacrypt.Main

Web Demo (Local)

cd web
npx serve . -l 3000
# Open http://localhost:3000

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📸 Screenshots

Encode Mode

Upload any image → Type a secret message → Download the encoded image

Decode Mode

Upload the encoded image → Reveal the hidden message

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🧠 Key Algorithm — LSB Encoding

// Set the Least Significant Bit
int modified = (value & 0xFE) | messageBit;
// 0xFE = 11111110 → clears the last bit
// Then OR with our message bit (0 or 1)

Each pixel stores 3 bits of the message (one in R, G, B). A 1024×1024 image can hide ~390,000 characters — an entire novel!

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📄 License

This project is built for educational purposes as a Core Java PBL Project.