securechat-py 1.0.1

Ultra-secure terminal-based chat with end-to-end encryption and decentralized networking

SecureChat

A spy movie style ultra-secure terminal-based bi-directional chatting application with end-to-end encryption, TLS transport security, and support for one-to-one, one-to-many, many-to-one, and many-to-many communication. Designed as a personal ultra-secure communication medium with comprehensive edge case handling.

Features

• End-to-End Encryption: RSA-based encryption for direct messages with digital signatures
• TLS Transport Security: All connections secured with SSL/TLS certificates
• Password-Protected Keys: Private keys encrypted with user passwords
• Group Chat: Create and join groups for multi-user conversations
• Offline Message Delivery: Receive unread messages when you log back in
• Real-time Communication: Instant message delivery with threading
• Cross-Platform: Works on Windows, Linux, Mac
• Federation Support: Connect multiple servers for decentralized communication
• Production-Ready: Robust error handling, connection management, and security

Security Features

Cryptographic Security

• RSA 2048-bit Keys: Generated per user with secure key derivation
• AES-GCM Encryption: Symmetric encryption for group messages with PBKDF2 key derivation
• Digital Signatures: PSS-based signatures for authenticity
• TLS 1.2+: Transport layer security with certificate validation
• Password Protection: Keys stored encrypted with strong passwords (8+ chars, mixed case, digits)
• Replay Prevention: Server-generated timestamps prevent replay attacks
• Certificate Validation: Automatic expiry checking and hostname validation for federation

Operational Security

• Rate Limiting: Prevents abuse with message rate controls
• Input Validation: Sanitized JSON communication with size limits
• Resource Limits: Maximum clients, message sizes, and connection timeouts
• Audit Logging: Security events logged to files
• Key Recovery: Automatic backup and regeneration for corrupted keys
• Message TTL: Automatic cleanup of old pending messages

Network Security

• Federation Authentication: Password-protected federation connections
• Certificate Pinning: SHA256 fingerprint validation for trusted federation servers
• Connection Timeouts: Prevents hanging connections
• IP-based Tracking: Basic connection monitoring
• Graceful Disconnection: Clean shutdown handling

Edge Cases Handled

Security Edge Cases

• Key Corruption: Automatic backup and regeneration
• Certificate Expiry: Validation and warning system
• Replay Attacks: Timestamp-based prevention
• Man-in-the-Middle: Certificate validation and hostname checking
• Key Conflicts: Username-based conflict resolution in federation

Network Edge Cases

• Connection Drops: Automatic reconnection and message queuing
• Server Crashes: Federation reconnection and state recovery
• Network Partitions: Message queuing for offline users
• High Latency: Non-blocking operations with timeouts
• Concurrent Connections: Thread-safe message handling

Data Integrity Edge Cases

• Message Corruption: JSON validation and size limits
• Storage Corruption: Timestamp-based message validation
• Database Issues: In-memory storage with periodic cleanup
• Large Messages: Size limits and validation
• Memory Exhaustion: Resource limits and cleanup threads

User Experience Edge Cases

• Duplicate Users: Server-side username validation
• Invalid Input: Comprehensive input sanitization
• Race Conditions: Thread-safe operations with locks
• Keyboard Interrupts: Graceful shutdown handling
• Password Errors: Recovery mechanisms for key loading

Federation Edge Cases

• Server Conflicts: ID-based conflict prevention
• Circular Dependencies: Loop detection in federation
• Partial Failures: Graceful degradation when servers disconnect
• User Migration: Cross-server user discovery
• Message Routing: Multi-hop message forwarding

Installation

Install from PyPI:

pip install securechat

Or install from source:

git clone https://github.com/i-soumya18/securechat.git
cd securechat
pip install .

Setup

1. Generate SSL certificates:

securechat generate-certs

2. Start the secure server:

securechat server --cert server.crt --key server.key

3. (Optional) Start additional servers for federation:

securechat server --port 12348 --cert server.crt --key server.key

Usage

Direct Messages (One-to-One)

securechat client localhost:12346 your_username

Then type: to alice: Hello spy!

Group Chat (One-to-Many/Many-to-Many)

• group create mygroup - Create a new group
• group join mygroup - Join an existing group
• group list - List available groups
• to group:mygroup: Message for all - Send to group

Federation (Cross-Server Communication)

• federate hostname:port - Connect to another SecureChat server
• Users from federated servers appear in your user list automatically

Commands

• list - Show all known users (local + federated)
• to username: message - Send direct message
• group create name - Create group
• group join name - Join group
• group leave name - Leave group
• group list - List groups
• federate host:port - Connect to federated server
• Ctrl+C to exit

Architecture

• Server: Multi-threaded SSL server handling connections, message routing, and federation
• Client: SSL client with real-time message handling, group management, and federation awareness
• Crypto: RSA for keys, AES for messages, PSS for signatures, certificate validation
• Groups: Server-managed group membership with broadcast messaging
• Federation: Server-to-server protocol for decentralized communication
• Storage: In-memory with periodic cleanup, file-based key storage

Security Best Practices

1. Use Strong Passwords: At least 8 characters for key encryption
2. Keep Certificates Updated: Regenerate before expiry
3. Monitor Logs: Check server logs for security events
4. Network Security: Run behind firewalls, use VPNs for remote access
5. Key Backup: Keep backups of key files in secure locations
6. Regular Updates: Keep dependencies updated for security patches

Troubleshooting

Certificate Issues

• Regenerate certificates: securechat generate-certs
• Check expiry: Server logs show certificate status on startup

Connection Issues

• Verify server is running: Check for "Secure server started" message
• Check firewall settings for the configured ports
• Use localhost for local testing, actual hostname/IP for remote

Federation Issues

• Ensure both servers have valid certificates
• Check server logs for federation handshake messages
• Verify ports are open (main port + federation port +1)

Key Issues

• Delete corrupted key files to regenerate
• Backups are created automatically for recovery

Perfect for secure communications in any scenario! 🕵️‍♂️🔐 (Windows, Linux, Mac)