🔐 SafeChat - A Secure Messaging App Using Real Cryptography

Ever wondered how encrypted messaging actually works?
SafeChat is a secure terminal-based chat application that puts cryptographic theory into practical use, built as part of my Applied Cryptography Lab project.

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💡 Overview

SafeChat is a Python-based messaging system that lets users exchange encrypted messages using AES-256. It also includes secure user authentication using PBKDF2 with HMAC-SHA256 and a JSON-based user store.

This project was developed by Kavish Gulati under the guidance of Dr. Gururaj H L, for partial fulfillment of the Applied Cryptography Lab.

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🔐 Features

• End-to-End AES-256 Encryption

  • Messages are encrypted with a user-defined key before being sent.
  • Uses CBC mode with PKCS7 padding for secure message blocks.

• Secure User Authentication

  • Passwords are never stored in plaintext.
  • Implements PBKDF2 hashing with per-user salts.

• Encrypted Logging

  • Messages are logged in both plaintext and encrypted formats for educational use.
  • The logs are securely deleted when the app is restarted or closed.

• Modular Design

  • All cryptographic operations are abstracted into a utility module for easy understanding and reuse.

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🛠️ Tech Stack

• Language: Python 3
• Encryption: AES-256 (CBC)
• Hashing: PBKDF2-HMAC-SHA256
• Data Storage: JSON
• UI: Command-Line Interface (CLI)

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🚀 How It Works

Download the requirements

pip install -r requirements.txt

1. Register / Login

Users register with a username and password. Passwords are hashed and salted using PBKDF2 and stored securely.

2. Start Server

Launch the server:

python server.py

3. Connect Clients

Run the client app and log in:

python client.py

Each message typed is encrypted on the sender's side and decrypted on the receiver's end—using the same key derived from the login session.

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📦 Project Structure

├── client.py           # Handles user input and message sending/receiving
├── server.py           # Manages multiple client connections
├── crypto_utils.py     # Encryption, decryption, and hashing functions
├── message_logger.py   # Handles encrypted logging and deletion
├── users.json          # Stores user credentials securely (hashed + salted)

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🌱 Future Plans

• Add a Tkinter or PyQt GUI
• Integrate secure key exchange (e.g., Diffie-Hellman)
• QR code-based login/authentication
• TLS/SSL-based encrypted socket connections

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🙌 Acknowledgments

Built with lots of late-night debugging and coffee by Kavish Gulati,
under the supervision of Dr. Gururaj H L.

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📜 License

This project is open-source for learning purposes. Contributions and suggestions are welcome!

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🔗 Let's Connect

Feel free to connect with me on LinkedIn or contribute to the repo!