Beacon Server and Client Communication System

Overview

This project demonstrates a secure client-server communication system implemented in Java. The system includes a server that handles multiple client connections and facilitates message broadcasting, and a client application that connects to the server, encrypts messages, and ensures secure communication.

Features

• Multi-client Support: Server supports multiple clients simultaneously.
• Authentication: Clients authenticate using unique User IDs.
• Message Encryption: Messages are securely encrypted using XOR and SHA-256-based keys.
• Broadcast Messaging: Server broadcasts messages to all connected clients except the sender.
• Timestamped Messages: Each message includes a timestamp.

Technologies Used

• Java: Programming language for both server and client applications.
• Socket Programming: For communication between server and clients.
• SHA-256: Secure hashing algorithm used to generate encryption keys.
• XOR Encryption: Lightweight encryption/decryption method for secure messaging.

File Structure

• BeaconServer.java: Handles server operations, including client management and broadcasting.
• Client.java: Client-side application for connecting to the server and sending/receiving messages.
• Message.java: Represents a message with metadata like content, sender, and timestamp.

How to Run

1. Login: Enter any desired User ID in the corresponding field. This User ID will be visible to other users.
2. Server Address: Enter the server address (IP or domain). If testing locally, use "localhost" or "127.0.0.1" (without quotes). If no address is entered, the default behavior will use "127.0.0.1".
3. Login: After filling out the User ID and Server Address, click Login or press Enter while in one of the text fields.
4. Message Sending: Once logged in, you can compose and send messages. These messages will be visible to all other logged-in users, and their User IDs will appear in the user list on the right.
   • Messages are encrypted but can be read by all users logged into the server.
   • The server can see the encrypted message and the sender’s information, but it cannot read the plaintext message content.
5. Disconnect: To disconnect and return to the login screen, click the Disconnect button at the top left. You can also close the window to terminate the program.
6. Terminate Server (if running): If you are running the server, you can terminate it by using the key combination Ctrl + C in the terminal window where the server is running.