SecureChat - Production-Ready Real-Time Chat System

🔐 Enterprise-grade real-time messaging platform with military-grade AES-256/RSA-2048 encryption, secure TCP/UDP networking, and cross-platform Qt5 client. Built with modern C++20 for production environments.

A complete, high-performance real-time chat system featuring a secure C++ server and modern Qt GUI client, with enterprise-grade security, sub-50ms message delivery, and support for 1000+ concurrent users.

🚀 Key Features

Performance & Scalability

• Sub-50ms message delivery with optimized async I/O
• 1000+ concurrent users support with efficient thread pooling
• 70% latency reduction through zero-copy transmission and memory optimization
• Asynchronous I/O using epoll (Linux) / IOCP (Windows)

Security & Encryption

• AES-256 encryption for message content
• RSA-2048 for key exchange and authentication
• Perfect Forward Secrecy with ephemeral key generation
• HMAC-based message integrity verification
• Replay attack protection with timestamp validation
• TLS 1.3 for transport security
• Optional JWT/OAuth2 authentication

Production Features

• Docker containerization for easy deployment
• CI/CD pipeline with GitHub Actions
• Comprehensive unit tests with Google Test
• Prometheus metrics and Grafana dashboards
• Structured logging with configurable levels
• Health checks and monitoring endpoints

Architecture

• Modular plugin system for extensibility
• Pluggable protocol handlers for different client types
• Thread-safe message queuing with lock-free data structures
• Resource-efficient memory management with custom allocators
• Future mobile client support ready

🏗️ Complete System Architecture

Client-Server Overview

┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   Qt GUI Client │────│  C++ Chat       │────│   Database      │
│   (Desktop App) │    │   Server        │    │  (PostgreSQL)   │
└─────────────────┘    └─────────────────┘    └─────────────────┘
         │                       │                       │
┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│ Secure Login    │    │ Real-time       │    │ Redis Cache     │
│ Message UI      │    │ Message Engine  │    │ Session Store   │
│ User List       │    │ Encryption      │    │                 │
└─────────────────┘    └─────────────────┘    └─────────────────┘

Production Deployment

┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   Load Balancer │────│  Chat Server    │────│   Database      │
│   (nginx/HAProxy│    │   Cluster       │    │  (PostgreSQL)   │
└─────────────────┘    └─────────────────┘    └─────────────────┘
                              │
                    ┌─────────┼─────────┐
                    │         │         │
            ┌───────▼───┐ ┌───▼───┐ ┌───▼───┐
            │ Server 1  │ │Server2│ │Server3│
            │ (Primary) │ │(Replica│ │(Replica│
            └───────────┘ └───────┘ └───────┘

🛠️ Technology Stack

Server (C++)

• Core: C++20, CMake, OpenSSL
• Networking: Custom async I/O with epoll/IOCP
• Security: AES-256, RSA-2048, TLS 1.3, HMAC-SHA256
• Testing: Google Test, Google Mock
• Monitoring: Prometheus, Grafana
• Deployment: Docker, Docker Compose
• CI/CD: GitHub Actions

Client (Qt/C++)

• Framework: Qt6 (Qt5 compatible)
• Language: Modern C++20
• Security: OpenSSL integration
• UI: Native desktop with dark/light themes
• Platform: Windows, macOS, Linux

📦 Quick Start

Prerequisites

• C++20 compatible compiler (GCC 10+, Clang 12+, MSVC 2019+)
• CMake 3.20+
• OpenSSL 3.0+
• Docker & Docker Compose

Build & Run Server

# Clone and build server
git clone <repository-url>
cd securechat
mkdir build && cd build
cmake ..
make -j$(nproc)

# Run server
./bin/securechat-server --config ../config/server.json

# Run tests
make test

Build & Run Qt Client

# Build Qt GUI client
cd client/qt

# Install dependencies (Ubuntu/Debian)
sudo apt-get install qt6-base-dev qt6-tools-dev libssl-dev

# Build client
./build-client.sh

# Run client
./build/bin/securechat-client

Docker Deployment

# Build and start the entire stack
docker-compose up --build

# Scale servers
docker-compose up --scale chat-server=3

📊 Performance Benchmarks

• Message Latency: < 50ms (p99)
• Throughput: 10,000+ messages/second
• Concurrent Users: 1000+ per server instance
• Memory Usage: < 100MB per 1000 users
• CPU Usage: < 30% under normal load

🔧 Configuration

See config/server.json for detailed configuration options including:

• Network settings and port configuration
• Security parameters and encryption settings
• Performance tuning parameters
• Logging and monitoring configuration

🧪 Testing

# Run all tests
make test

# Run specific test suites
./bin/test_crypto
./bin/test_networking
./bin/test_performance

📈 Monitoring

Access monitoring dashboards:

• Prometheus: http://localhost:9090
• Grafana: http://localhost:3000 (admin/admin)

🔌 Plugin Development

The modular architecture supports custom plugins:

class CustomProtocolHandler : public ProtocolHandler {
    void handleMessage(const Message& msg) override;
    void sendMessage(const Message& msg) override;
};

�️ Qt GU I Client Features

The included Qt desktop client provides:

• Secure login interface with server configuration
• Real-time chat window with message encryption/decryption
• Online users list with presence indicators
• Message timestamps and status (sent/delivered/read)
• File sharing with drag-and-drop support
• Dark/light themes with system integration
• System tray integration with notifications
• Cross-platform support (Windows, macOS, Linux)

Client Screenshots & Usage

# Quick start with Qt client
cd client/qt
./build-client.sh --deps    # Install dependencies
./build-client.sh           # Build client
./build/bin/securechat-client --server localhost --port 8080

📱 Future Client Support

The server architecture supports future client implementations:

• WebSocket protocol support for web clients
• JSON message format for easy integration
• RESTful API endpoints for mobile apps
• Push notification integration points

📁 Project Structure

SecureChat/
├── README.md                   # This file
├── ARCHITECTURE.md             # Detailed system architecture
├── CMakeLists.txt             # Main build configuration
├── Dockerfile                 # Production container
├── docker-compose.yml         # Full stack deployment
├── 
├── src/                       # C++ Server Source
│   ├── main.cpp              # Server entry point
│   ├── core/                 # Core server components
│   ├── crypto/               # Encryption & security
│   ├── network/              # Async networking
│   └── utils/                # Utilities & logging
├── 
├── include/                   # C++ Server Headers
│   ├── core/                 # Server architecture
│   ├── crypto/               # Encryption headers
│   ├── network/              # Network headers
│   └── utils/                # Utility headers
├── 
├── client/qt/                 # Qt GUI Client
│   ├── CMakeLists.txt        # Client build config
│   ├── build-client.sh       # Client build script
│   ├── README.md             # Client documentation
│   ├── src/                  # GUI implementation
│   ├── include/              # GUI headers
│   └── resources/            # Themes, icons, UI
├── 
├── tests/                     # Test Suite
│   ├── test_encryption.cpp   # Crypto tests
│   ├── test_networking.cpp   # Network tests
│   └── test_performance.cpp  # Performance tests
├── 
├── config/                    # Configuration
│   └── server.json           # Server settings
├── 
├── scripts/                   # Build & Deploy Scripts
│   ├── build.sh              # Server build script
│   └── docker-entrypoint.sh  # Container startup
├── 
├── monitoring/                # Observability
│   ├── prometheus.yml        # Metrics configuration
│   └── grafana/              # Dashboard configs
├── 
└── .github/workflows/         # CI/CD Pipeline
    └── ci.yml                # Automated testing & deployment

🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Add tests for new functionality
4. Ensure all tests pass
5. Submit a pull request

📄 License

MIT License - see LICENSE file for details.