🔒 Secure Image Steganography Tool (WinForms + AES-GCM) 📖 Overview

This project is a Windows Forms application that lets you hide secret messages inside PNG images using steganography (Least Significant Bit method) and encrypt them with AES-256-GCM for strong security. The result is a normal-looking PNG file that secretly contains encrypted text — only someone with the right password can extract and decrypt it.

✨ Features 🖼 Embed text into PNG images using LSB steganography 🔐 AES-256-GCM encryption with PBKDF2 key derivation (200,000 iterations, SHA-256) 🔑 Password-protected message extraction 📊 Capacity calculation (how many bytes the chosen image can hide) 💾 Save the stego image as a new PNG file 👩‍💻 Simple WinForms GUI — no command-line needed

🚀 How to Use

1. Embedding a message Click Browse… to select a PNG image. Enter a password (used for AES encryption). Type your secret message into the text box. Click Embed (Encrypt + Hide). Save the new PNG with Save Stego PNG….

2. Extracting a message Open the stego PNG with Browse…. Enter the same password you used to embed. Click Extract (Reveal + Decrypt). The hidden message appears in the text box.

🛠 Technical Details Programming Language: C# Framework: .NET 6+ (Windows Forms) Encryption: AES-256-GCM Key Derivation: PBKDF2 with SHA-256, 200k iterations, 16-byte salt Steganography: LSB (Least Significant Bit) in R, G, and B channels (3 bits per pixel) File Format: PNG only (lossless — JPEG will destroy hidden data)

📂 Project Structure Secure_Image/ ├── Form1.cs # Main WinForms code (UI + logic) ├── Stego.cs # Steganography (LSB embed/extract) ├── Crypto.cs # AES-GCM + PBKDF2 encryption/decryption └── Program.cs # Application entry point

⚠️ Notes Only PNG images should be used (lossless format). If you use the wrong password, extraction will fail. Maximum message size depends on image resolution: capacity ≈ (width × height × 3) / 8 bytes

Example: 1024×768 image ≈ 288 KB max hidden data. 📸 Example Input: cat.png Hidden message: "Hello, this is a secret!" Output: cat_stego.png → looks identical, but contains the secret text.