🔐 PQXDH Protocol Simulator

Post-Quantum Extended Diffie-Hellman Key Exchange

About PQXDH

PQXDH is Signal's hybrid post-quantum key agreement protocol that combines classical X25519 elliptic curve cryptography with ML-KEM-1024 (formerly CRYSTALS-Kyber), a NIST-standardized post-quantum key encapsulation mechanism. This provides protection against both classical and quantum computer attacks.

Key Features: Post-quantum forward secrecy • Quantum-resistant • NIST FIPS 203 compliant • Production-ready (Signal Messenger)

Security Comparison: X3DH vs PQXDH

Feature X3DH (Classical) PQXDH (Hybrid)
Primary Key Exchange X25519 (Curve25519) X25519 + ML-KEM-1024
Quantum Resistance ❌ Vulnerable to Shor's Algorithm ✅ Quantum-Resistant
Forward Secrecy ✅ Yes (classical) ✅ Yes (post-quantum)
Protection Timeline Until ~2035 (quantum threat) 2025+ (current protection)
NIST Standardized NIST SP 800-186 NIST FIPS 203 (Aug 2024)
Key Size 32 bytes (256-bit) 32 bytes + 1568 bytes (KEM)
Performance ~1ms ~10-20ms
Production Use Signal (2016-2023) Signal (2023+)
⚠️ Educational Prototype Notice: This is a simplified educational demonstration using browser-based cryptography. The actual PQXDH protocol includes additional security measures, authentication, and key validation. For production use, refer to Signal's official specification and use audited cryptographic libraries.