QSSL - Quantum-Safe Secure Layer

Patent-free post-quantum TLS using SPHINCS+ KEM for key exchange. Implements NIST-standardized algorithms with traffic analysis resistance for organizations requiring post-quantum security without patent encumbrances.

Security Status

Recommendation: Suitable for research, testing, and PQC migration planning. Security audit recommended before deployment with sensitive data.

Why Patent-Free Matters

The Patent Landscape:

• ML-KEM (Kyber) has patent claims that create licensing uncertainty for enterprise deployment
• SPHINCS+ is hash-based with no known patent encumbrances
• Organizations with legal/compliance requirements need patent-free alternatives

QSSL's Approach:

• Default: SPHINCS+ KEM for key exchange (patent-free)
• Optional: ML-KEM/Kyber for compatibility when patents are acceptable
• Clear labeling: Cipher suites indicate patent status

Cipher Suites

Key Features

• Patent-Free Default: SPHINCS+ KEM avoids licensing concerns
• Traffic Analysis Resistance: Fixed-size frames prevent metadata leakage
• NIST Algorithms: Falcon (FIPS 204), SPHINCS+ (FIPS 205), ML-KEM (FIPS 203)
• Memory Safety: Rust with automatic zeroization
• Async/Await: Built on Tokio for high performance
• Algorithm Agility: Easy to swap PQC algorithms

Quick Start

# Install from crates.io
cargo add qssl

# Or build from source
git clone https://github.com/Paraxiom/qssl
cd qssl
cargo build --release

Basic Usage

use qssl::{QsslConnection, QsslConfig, CipherSuite};

// Client with patent-free cipher suite
let config = QsslConfig::builder()
    .cipher_suite(CipherSuite::SPHINCS_FALCON512_AES256)
    .build();

let conn = QsslConnection::connect("server:4433", config).await?;
conn.send(b"Hello Quantum World").await?;
let response = conn.recv().await?;

// Server
let listener = QsslListener::bind("0.0.0.0:4433", server_config).await?;
let conn = listener.accept().await?;

Architecture

┌─────────────────────────────────────────────────────────────────┐
│                      Application Layer                          │
├─────────────────────────────────────────────────────────────────┤
│                      QSSL Connection                            │
│           (Handshake, State Machine, Session)                   │
├─────────────────────────────────────────────────────────────────┤
│                      QSSL Transport                             │
│      (Fixed-Size Records, Encryption, Sequencing)               │
├─────────────────────────────────────────────────────────────────┤
│                 Post-Quantum Cryptography                       │
│    SPHINCS+ KEM (default) │ ML-KEM │ Falcon │ SPHINCS+ Sig     │
├─────────────────────────────────────────────────────────────────┤
│                    Symmetric Crypto                             │
│              AES-256-GCM │ ChaCha20-Poly1305                    │
├─────────────────────────────────────────────────────────────────┤
│                      Network (TCP)                              │
└─────────────────────────────────────────────────────────────────┘

Feature Status

Implemented

• SPHINCS+ KEM key exchange (patent-free default)
• ML-KEM/Kyber key exchange (optional)
• Falcon-512/1024 signatures
• SPHINCS+ signatures
• AES-GCM and ChaCha20-Poly1305 encryption
• Fixed-size frame transport (traffic analysis resistance)
• Post-quantum X.509-style certificates
• Session management
• HKDF key derivation

In Development

• Certificate chain validation
• Full session resumption
• 0-RTT support
• OCSP stapling

Performance

Benchmarks on Apple M1:

SPHINCS+ is slower but patent-free. Choose based on your requirements.

Integration

With QSSH

QSSL can serve as the transport layer for QSSH:

use qssl::integrations::qssh::QsshTransport;

let transport = QsshTransport::connect("server:22", config).await?;

With Web Servers

server {
    listen 443 qssl;
    qssl_certificate cert.pem;
    qssl_certificate_key key.pem;
    qssl_ciphers SPHINCS_FALCON512_AES256;  # Patent-free
}

Security Considerations

Comparison with Existing Solutions

Formal Verification

qssl includes Lean 4 machine-checked proofs (Tier 3 of our Kani → Verus → Lean pipeline):

cd lean && lake build   # 0 errors, 0 warnings

Roadmap

• Formal verification (Lean 4 — 100 theorems)
• Certificate chain validation
• 0-RTT session resumption
• WASM support
• C FFI bindings
• Python bindings

Documentation

• API Documentation
• Changelog

License

Dual-licensed under MIT and Apache-2.0.

Acknowledgments

• NIST Post-Quantum Cryptography standardization
• pqcrypto crate family
• Part of the Paraxiom quantum-safe protocol suite

QSSL - Patent-free post-quantum TLS for the quantum era.