🔐 Secure P2P Encrypted Chat (Python)

A peer-to-peer (P2P) secure chat application built using Python sockets with end-to-end encryption using **RSA + AES-GCM**.

This project allows multiple users connected to the same network (Wi-Fi/LAN) to communicate securely without a central server.

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## 🚀 Features

- 🔐 End-to-End Encryption (RSA + AES-GCM)
- 📡 Peer-to-Peer Communication (No Server Required)
- ⚡ Fast TCP Socket Messaging
- 👤 Username-based Messaging
- 🔁 Automatic Reconnection Handling
- 🧵 Multi-threaded Client Handling
- 🛡 Secure Key Exchange (RSA OAEP)

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## 🧠 How It Works

1. Each user generates an RSA key pair.
2. When connecting:
   - Users exchange public keys.
   - A secure AES session key is generated.
   - AES key is encrypted using RSA.
3. Messages are encrypted using AES-GCM before sending.
4. Receiver decrypts messages securely.

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## 📦 Requirements

Install dependencies:

```bash
pip install cryptography

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▶️ Usage

Step 1: Run the script

python chat.py

Step 2: Enter your name

Your name: Guhan

Step 3: Add peer IPs (same Wi-Fi)

Peer IP: 192.168.1.5
Peer IP: 192.168.1.6

Step 4: Start chatting 🎉

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🌐 Network Requirements

• All devices must be on the same Wi-Fi/LAN
• Firewall should allow port 7777

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🛠 Project Structure

chat.py        # Main application
README.md      # Documentation
LICENSE        # License file

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🔒 Security Details

• RSA (2048-bit) for key exchange
• AES-GCM (128-bit) for message encryption
• Unique nonce per message
• Protection against replay attacks

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⚠ Limitations

• Works only in local network (LAN/Wi-Fi)
• No message persistence (no database)
• Manual IP input required

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🤝 Contributing

Feel free to fork and improve this project!

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👨‍💻 Author

Guhan Senthil