Post-Quantum Cryptography · NYU CS6903 · 2026
Kyber Crystals: Post-Quantum Secure Channel
A research-grade C implementation of a post-quantum-secure channel between two endpoints (Alice ↔ Bob), implemented twice with two different families of post-quantum primitives, then attacked and benchmarked under a unified test harness.
Approach
Scheme A is the mainstream lattice stack: ML-KEM-768 (Kyber) for key encapsulation and ML-DSA-65 (Dilithium) for signatures. Scheme B deliberately avoids lattices entirely: HQC-192, a code-based KEM, paired with SLH-DSA-SHA2-192s (SPHINCS+), a hash-based signature scheme. Both run at NIST PQ security Category 3 and share the same symmetric layer — AES-256-GCM with HKDF-SHA256 key derivation.
The point of building it twice: if structured lattices ever fall to cryptanalysis, everything deployed on Kyber+Dilithium falls together. Both backends sit behind a single pluggable pq_backend_t interface, selected at runtime — a working demonstration of what crypto-agility costs and buys you.
Highlights
- Two full PQ backends behind one C interface — switch with --backend A / --backend B
- Automated attack demos: replay, downgrade, and AEAD tampering — run as failing-build tests
- Docker benchmark harness comparing handshake latency, key/ciphertext/signature sizes
- Built on liboqs; reproducible with make build / make test / make benchmark