KyberMat: Efficient Accelerator for Matrix-Vector Polynomial Multiplication in CRYSTALS-Kyber Scheme via NTT and Polyphase Decomposition

TL;DR

This paper presents KyberMat, a hardware accelerator that significantly improves the efficiency of matrix-vector and polynomial multiplications in the Kyber post-quantum cryptography scheme through innovative algorithm and architecture optimizations.

Contribution

It introduces a novel sub-structure sharing technique and a hardware co-design for optimized matrix-vector and polynomial multiplication in Kyber, achieving high speed and low latency.

Findings

90% reduction in execution time on FPGA

66x increase in throughput performance

Efficient utilization of hardware components

Abstract

CRYSTAL-Kyber (Kyber) is one of the post-quantum cryptography (PQC) key-encapsulation mechanism (KEM) schemes selected during the standardization process. This paper addresses optimization for Kyber architecture with respect to latency and throughput constraints. Specifically, matrix-vector multiplication and number theoretic transform (NTT)-based polynomial multiplication are critical operations and bottlenecks that require optimization. To address this challenge, we propose an algorithm and hardware co-design approach to systematically optimize matrix-vector multiplication and NTT-based polynomial multiplication by employing a novel sub-structure sharing technique in order to reduce computational complexity, i.e., the number of modular multiplications and modular additions/subtractions consumed. The sub-structure sharing approach is inspired by prior fast parallel approaches based on polyphase decomposition. The proposed efficient feed-forward architecture achieves high speed, low latency, and full utilization of all hardware components, which can significantly enhance the overall efficiency of the Kyber scheme. The FPGA implementation results show that our proposed design, using the fast two-parallel structure, leads to an approximate reduction of 90% in execution time, along with a 66 times improvement in throughput performance.