Deferred Reduction Optimizations for Post-Quantum Lattice Cryptography: ML-KEM and ML-DSA

This paper presents a unified framework of deferred modular reduction optimizations for the newly standardized post-quantum cryptographic algorithms ML-KEM (FIPS 203) and ML-DSA (FIPS 204). Our approach exploits coefficient bound analysis to minimize expensive arithmetic operations while preserving constant-time execution guarantees. Key contributions:

• ML-KEM Polynomial Vector Multiplication: Operation fusion, common subexpression elimination (Mulcache), and lazy 32-bit accumulation achieving 3.5–4× speedup
• ML-KEM Lazy INTT: 3-layer deferred reduction with formal safety bounds providing 2.25× speedup
• ML-DSA Radix-4 NTT: Hybrid radix-2/radix-4 implementation based on DFT composition theory yielding 16% signing improvement
• ML-DSA Lazy Reduction Chains: Deferred reduction in matrix-vector multiplication achieving 12% verification speedup

All optimizations are validated against official NIST Known Answer Test (KAT) vectors. The techniques are implemented in HPCrypt, an open-source high-performance post-quantum cryptography library written in Rust with optional SIMD acceleration (AVX2, AVX-512, NEON). Keywords: post-quantum cryptography, ML-KEM, ML-DSA, NTT, lazy reduction, FIPS 203, FIPS 204, lattice cryptography, performance optimization Related identifiers:
GitHub: https://github.com/seceq/hpcrypt