Key Exchange Algorithms
Key exchange algorithms enable two parties to establish a shared secret over an insecure channel, forming the foundation of secure communication protocols.
Available Key Exchange Algorithms
Classical Key Exchange
X25519
Elliptic curve Diffie-Hellman key exchange using Curve25519.
- Security Level: 128-bit equivalent
- Key Size: 32 bytes (public and private)
- Shared Secret: 32 bytes
- Use Cases: TLS, Signal Protocol, SSH, VPN
Algorithm Comparison
| Algorithm | Type | Security Level | Key Size | Performance |
|---|---|---|---|---|
| X25519 | Classical ECDH | 128-bit | 32 bytes | Very Fast |
| ML-KEM-768 | Post-Quantum | 192-bit | 1,184 bytes | Fast |
Security Considerations
Classical vs Post-Quantum
- X25519: Secure against classical computers, vulnerable to quantum computers
- ML-KEM-768: Secure against both classical and quantum computers
- Hybrid Approach: Combine X25519 + ML-KEM-768 for transition period
Best Practices
- Always use ephemeral keys for forward secrecy
- Validate public keys before use
- Use proper key derivation from shared secret
- Implement constant-time operations
Selection Guide
For Current Applications
- Primary: X25519 (fast, widely supported)
- Backup: ECDH P-256 (broader compatibility)
For Post-Quantum Transition
- Hybrid: X25519 + ML-KEM-768
- Future: ML-KEM-768 only
For Specific Use Cases
- TLS 1.3: X25519 or hybrid
- Signal Protocol: X25519
- SSH: X25519 or Ed25519 (for signatures)
- VPN: X25519 or hybrid approach
Implementation Notes
All key exchange algorithms in MetaMUI Crypto Primitives provide:
- ✅ Constant-time implementations
- ✅ Side-channel resistance
- ✅ Proper key validation
- ✅ Cross-platform compatibility
- ✅ Standards compliance