🌍 Platform Support

🏰 Citadel Protocol

A post-quantum secure networking protocol that makes developing hyper-secure client-server and P2P applications easy. Built with 100% safe Rust, it provides a robust foundation for creating secure, high-performance network applications with built-in NAT traversal and post-quantum cryptography using a very low memory footprint.

📑 Table of Contents

• 🌟 Key Features
• 🚀 Quick Start
• 🔒 Security Architecture
• 📂 Remote Encrypted Virtual Filesystem
• ⚡ Threading Modes
• 💾 Backend Storage
• 📚 Documentation
• 📜 Patent and Open Source
• 🧪 Testing
• 🛡️ Security Considerations
• 🤝 Contributing
• ⚖️ License
• 📞 Contact
• 🎯 Examples

🌟 Key Features

• 🔒 Advanced Post-Quantum Security - Novel multi-layered ratcheting algorithm
• 🛡️ Customizable Security Modes - Balance between security and performance
• 📂 Remote Encrypted Virtual Filesystem - Secure remote storage solution
• ⚡ Flexible Threading Modes - Single and multi-threaded operation
• 💾 Multiple Backend Options - Various storage solutions
• 🌐 Built-in NAT Traversal - No port forwarding required
• 📱 Cross-Platform Support - Run anywhere
• 🚀 High Performance - Low latency, minimal resource usage
• 🔍 Zero Trust Architecture - End-to-end encryption

🔐 Advanced Post-Quantum Security

Multiple Key Encapsulation Mechanism (KEM) families:

• Kyber (default) - NIST standardized
• NTRU (Sntrup761)

Novel Multi-layered Security Architecture:

• Patent-pending multi-layered ratcheting algorithm
• Per-message re-keying mechanism
• Multi-layered key exchange protocol
• Multi-layered encryption with customizable algorithms
• Encryption algorithms:
  • AES-256-GCM
  • ChaCha20-Poly1305
  • Ascon-80pq
  • Novel Kyber "scramcryption" for enhanced security
• Customizable Security Modes:
  • True Perfect Forward Secrecy (PFS) mode with advanced ratcheting
  • Best-effort Mode (BEM) for high-throughput scenarios
  • Configurable security levels and algorithm combinations

🌐 Flexible Network Architecture

• Client-Server and P2P support
• Built-in NAT traversal with STUN/TURN capabilities
• Multiple transport protocols:
  • TCP
  • TLS (default)
  • QUIC
• WebRTC compatibility (optional feature)

⚡ Advanced Features

• Remote Encrypted Virtual Filesystem (RE-VFS)
• Device-dependent and credential-based authentication
• Automatic peer discovery

💾 Backend Storage Options

• Local filesystem (default)
• Redis support
• SQL support (MySQL, PostgreSQL, SQLite)

🚀 Quick Start

📋 Prerequisites

• Rust toolchain
• OpenSSL
• Clang

📥 Installation

1. Add to your Cargo.toml:

[dependencies]
citadel_sdk = "latest_version"

2. Setup the development environment:

cargo make install

💻 Basic Usage

🖥️ Server Example

use citadel_sdk::prelude::*;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let server = NodeBuilder::default()
        .with_node_type(NodeType::server("127.0.0.1:25021")?)
        .build(EmptyKernel::default())?;
    
    server.await?;
    Ok(())
}

📱 Client Example

use citadel_sdk::prelude::*;
use futures::StreamExt;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create server connection settings
    let server_connection_settings = ServerConnectionSettingsBuilder::credentialed_registration(
        "127.0.0.1:12345",
        "my_username",
        "My Name",
        "notsecurepassword",
    )
    .build()?;

    // Create client kernel
    let kernel = SingleClientServerConnectionKernel::new(
        server_connection_settings,
        |connect_success, remote| async move {
            let (sink, mut stream) = connect_success.channel.split();
            while let Some(message) = stream.next().await {
                // Handle incoming messages
            }
            Ok(())
        }
    )?;

    // Execute the application
    NodeBuilder::default().build(client_kernel)?.await?;
    Ok(())
}

🔒 Security Architecture

The Citadel Protocol implements a novel multi-layered security approach that goes beyond traditional encryption methods:

🔄 Multi-layered Ratcheting

• Implements an advanced patent-pending ratcheting algorithm that operates across multiple security layers
• Each layer maintains its own independent key schedule
• Provides enhanced forward secrecy by frequently rotating keys at different intervals
• Resistant against quantum attacks through post-quantum primitives

🛡️ Security Modes

• True Perfect Forward Secrecy (PFS):
  • Enforces re-keying on a per-message basis
  • Guarantees maximum security for messaging applications
  • Each message uses a new key derived from the previous state
  • Complete forward secrecy at message granularity
• Best-effort Mode (BEM):
  • Optimized for high-performance scenarios
  • Re-keys as frequently as possible without blocking message transmission
  • Maintains security while prioritizing throughput
  • Ideal for streaming and high-bandwidth applications

🔑 Multi-layered Key Exchange

• Multiple independent key exchanges occur simultaneously
• Combines post-quantum KEMs with traditional algorithms
• Provides defense in depth against both classical and quantum attacks
• Configurable algorithm selection for each layer

⚙️ Customizable Security Levels

• Flexible security modes to balance performance and security
• Perfect Forward Secrecy (PFS) mode with advanced ratcheting
• Best-effort Mode (BEM) for high-performance requirements
• Configurable algorithm combinations per security layer

⚡ Threading Modes

The Citadel Protocol provides flexible threading configurations to accommodate different performance requirements and use cases:

Single-Threaded Mode (Default)

• 🚀 Optimized for low-latency and minimal resource usage
• 📉 Extremely low memory footprint
• ⚡ Rapid message processing with zero thread context switching
• 🎯 Ideal for:
  • Edge devices and IoT applications
  • Real-time communication systems
  • Memory-constrained environments
  • Applications prioritizing consistent low latency

Multi-Threaded Mode

• 🔄 Parallel processing for high-throughput scenarios
• 🌐 Enhanced scalability for concurrent connections
• 💪 Optimal CPU utilization across multiple cores
• 🎯 Perfect for:
  • Server applications handling numerous concurrent clients
  • High-traffic network services
  • CPU-intensive processing tasks
  • Systems requiring maximum throughput

Enable multi-threaded mode by setting the appropriate feature flag:

[dependencies]
citadel_sdk = { version = "latest_version", features = ["multi-threaded"] }

📂 Remote Encrypted Virtual Filesystem

The Remote Encrypted Virtual Filesystem (RE-VFS) is a unique feature that enables secure remote data storage with unprecedented security guarantees:

🌟 Key Features

• Store encrypted data on any remote node (peer or server)
• Physical separation of data and decryption keys
• Requires compromising both storage location and client for data access
• Perfect for distributed secure storage solutions

🔒 Security Architecture

• Data is encrypted locally using Kyber public key encryption
• Decryption key is never stored with the data
• Uses Kyber scramcryption for minimal ciphertext size
• Optional multiple encryption layers for enhanced security

🎯 Use Cases

• Secure cloud storage alternatives
• Distributed backup systems
• P2P file sharing with enhanced security
• Secure document management systems

💻 Example Usage

use citadel_sdk::fs;

async fn store_file(remote: &mut NodeRemote) -> Result<(), Error> {
    // Write file with reinforced security
    fs::write_with_security_level(
        remote,
        "local_file.pdf",
        SecurityLevel::Reinforced,
        "/virtual/path/output.pdf"
    ).await?;

    // Read file back
    let local_path = fs::read(remote, "/virtual/path/output.pdf").await?;
    Ok(())
}

💾 Backend Storage

The Citadel Protocol offers flexible data persistence options to suit various deployment scenarios:

📈 Available Backends

• 🔒 In-Memory Storage:

  • Fastest performance
  • Perfect for temporary sessions
  • Ideal for testing and development

• 💻 Filesystem Backend (default):

  • Persistent storage using local filesystem
  • Automatic file management
  • Suitable for single-node deployments

• 📈 SQL Databases:

  • MySQL: Enterprise-grade reliability
  • PostgreSQL: Advanced features and scalability
  • SQLite: Embedded database option

• 📈 Redis Backend:

  • High-performance caching
  • Distributed deployment support
  • Perfect for session management

📊 Features

• Seamless switching between backends
• Automatic data serialization/deserialization
• Concurrent access support
• Transaction support (where applicable)
• Built-in connection pooling

📚 Documentation

• 📖 SDK Documentation
• 📚 API Reference
• 📁 Examples
• 📄 Technical Architecture

📜 Patent and Open Source Commitment

The Citadel Protocol's core technology is a patent-pending innovative security architecture that combines multiple novel features into a unique, highly secure communication system. Despite the patent protection, we remain committed to keeping this technology free and open source for the benefit of the entire community. This approach ensures that:

• The protocol remains freely available for everyone to use
• The patent serves to protect the technology from being closed-source or restricted
• Innovation and security improvements can continue to be community-driven
• The core technology stays accessible while being legally protected from potential abuse

🧪 Testing

The project includes comprehensive test suites. Use cargo-make for running tests:

# Install cargo-make
cargo install --force cargo-make

# Run local tests
cargo make test-local

# Run comprehensive tests (requires SQL/Redis setup)
cargo make test

🛡️ Security Considerations

While the Citadel Protocol implements cutting-edge security features:

• The project is pending third-party security audits
• Core cryptographic primitives come from verified Open Quantum Safe (OQS) and PQClean projects
• For maximum security, consider using hybrid cryptography with TLS/QUIC as underlying protocols

🤝 Contributing

Contributions are welcome! Here's how you can help:

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Submit a pull request

Please ensure your code:

• Follows Rust best practices
• Includes appropriate tests
• Is properly documented
• Passes all CI checks

⚖️ License

This project is dual-licensed for maximum permissibility under:

• MIT License
• Apache License 2.0

📞 Contact

• 🌐 Website
• 💬 Slack Community
• 📝 GitHub Issues

👥 Maintainers

• 👨‍💻 Thomas Braun - Inventor and Core Developer
• 👨‍💻 Donovan Tjemmes - Developer