Invisible Ink 🕵️‍♂️

A secure steganography tool combining AES-based encryption with LSB (Least Significant Bit) image manipulation.

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📖 Overview

Invisible Ink is a Python-based CLI tool designed to hide sensitive text messages inside PNG images.
Unlike traditional steganography tools that simply hide plain text, Invisible Ink focuses on security:

1. Encrypt-then-Hide: The message is encrypted before being embedded.
2. LSB Steganography: Encrypted bits are hidden in the least significant bits of the image pixels.
3. Passphrase-Based Access: Hidden data can only be recovered with the correct password.

Use it for secure communication, watermarking, or learning the fundamentals of cybersecurity and image processing.

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✨ Features

• 🔒 Symmetric encryption (Fernet / AES-based)
• 🖼️ LSB steganography on lossless PNG files
• 🔑 Password-protected message extraction
• 💻 Simple CLI interface
• 📚 Great for cybersecurity learning

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⚙️ Installation

Prerequisites

• Python 3.8+
• pip

Setup

1. Clone the repository

   git clone https://github.com/osmankaankars/Invisible-Ink.git
   cd Invisible-Ink

2. Create and activate a virtual environment

   python3 -m venv venv
   source venv/bin/activate      # Windows: venv\Scripts\activate

3. Install dependencies

   pip install -r requirements.txt

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🚀 Usage

1️⃣ Hide a Message (Encrypt & Embed)

python invisible_ink.py hide -i input.png -o output.png -m "This is a top secret message!"

You will be prompted for a password.
The tool will encrypt the message and embed it into the output image.

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2️⃣ Reveal a Message (Extract & Decrypt)

python invisible_ink.py reveal -i output.png

Enter the same password used during encryption.
If correct, the decrypted message will be printed.

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🔧 Command-Line Options

hide

• -i, --input : Input PNG file
• -o, --output: Output PNG file
• -m, --message: Message to hide

reveal

• -i, --input : Image containing hidden data

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🛠️ Technical Details

Encryption

• Uses Fernet (AES-128 + HMAC-SHA256)
• Password → SHA-256 hash → URL-safe key

Image Processing

• Based on Pillow (PIL)
• Reads and modifies pixel arrays

Encoding Strategy

• Converts encrypted payload to binary
• Embeds bits into LSB of the Red channel of each pixel
• Works only with lossless formats (PNG)

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⚠️ Disclaimer

This tool is for educational, research, and ethical security use only.
The author is not responsible for misuse.

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👨‍💻 Author

Osman Kaan Kars
Cybersecurity Engineer | SAP Security Specialist

• GitHub: https://github.com/osmankaankars
• LinkedIn: https://www.linkedin.com/in/osman-kaan-kars/

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