Cryptography

Optional hybrid post-quantum security.

QAL VPN supports optional hybrid key exchange behavior to complement conventional high-speed tunneling with additional quantum-resilient key material.

Hybrid model

Hybrid mode combines X25519 and ML-KEM-768 contributions into derived key material. This avoids reliance on a single primitive and improves long-term confidentiality posture against harvest-now-decrypt-later risk.

User-controlled activation

Post-quantum mode is off by default. Users can enable it when required by policy or risk profile, balancing compatibility, performance, and security objectives.

Operational compatibility

QAL VPN is designed to support mixed-mode operation, so users and teams can adopt post-quantum settings progressively without disrupting baseline connectivity. Classical WireGuard mode remains available for broad compatibility.

Classical baseline (always available)

Baseline transport uses WireGuard cryptography primitives: Curve25519 key agreement, ChaCha20-Poly1305 AEAD, BLAKE2s hashing, and HKDF-based key schedule.

Implementation principle

QAL VPN treats post-quantum cryptography as an additive control that can be enabled where needed, rather than a one-size-fits-all mandatory mode. This supports a safer migration path for real users.

Current hybrid design (Phase 2)

  • Client creates ephemeral X25519 key pair.
  • Client encapsulates to server ML-KEM-768 public key.
  • Both contributions are combined into a tunnel preshared key.
  • Resulting keying material is used only when PQ mode is enabled.