Secure TLS Chat (Python)

TLS-encrypted console chat server/client with mutual certificate authentication.

What it does

• Starts a threaded TCP chat server secured with TLS.
• Connects clients over TLS, authenticating both server and client certificates.
• Broadcasts messages to all connected peers with timestamps.
• Provides a helper script to generate self-signed cert/key pairs for local use.

Key features

• Mutual TLS: Server requires client certificates; client verifies the server certificate (hostname check disabled for dev).
• Broadcast chat: Server relays each message to all connected clients.
• Threaded handling: Each client runs on its own thread for concurrency.
• Certificate tooling: generate_cert.py produces server.crt/key and client.crt/key.
• Logging: INFO-level logging for connections, certificates, and messages.
• Graceful prompts: Client preserves the input prompt when new messages arrive.

Tech stack

• Python 3 (socket, ssl, threading, logging)
• cryptography (certificate generation)
• pyOpenSSL (listed dependency)

Architecture overview

Simple threaded TCP server wrapped in TLS. Each accepted socket is upgraded to TLS, tracked, and broadcast to peers.

[client] ==TLS==> [server:8443] ==TLS==> [client]
             \__ thread per client __/

Getting started (local)

Prerequisites

• Python 3.x
• pip

Install

pip install -r requirements.txt

Generate certificates

Run once to create local dev certs/keys in the project root:

python generate_cert.py

This produces server.crt, server.key, client.crt, client.key (gitignored).

Run the server

python server.py

• Listens on localhost:8443 by default; adjust host/port in SecureChatServer if needed.
• Expects server.crt, server.key, and client.crt in the working directory.

Run a client

In separate terminals:

python client.py

• Uses localhost:8443 by default; adjust host/port in SecureChatClient if needed.
• Expects client.crt, client.key, and server.crt in the working directory.
• Enter a username when prompted; type messages to broadcast or quit to disconnect.

Usage

1. Start the server.
2. Launch one or more clients after generating certificates.
3. Provide usernames and chat; messages show as username: message with server-side timestamps for logs.
4. Type quit to leave; server logs disconnections.

Testing / Quality

• No automated tests or linters are included in the repository.

Deployment

• No deployment configuration is provided; current setup targets local development with self-signed certificates.