A High-Speed Hardware Architecture of an NTT Accelerator for CRYSTALS-Kyber

Abstract

CRYSTALS-Kyber has emerged as a notable lattice-based post-quantum cryptography (PQC) scheme. As one of the four finalists in NIST's PQC standardization round three, CRYSTALS-Kyber is the only encryption algorithm demonstrating superior performance compared to other algorithms. The number theoretic transform (NTT) is employed to optimize polynomial multiplication, which constitutes the most complex operation within CRYSTALS-Kyber. This study introduces a high-speed NTT accelerator architecture, featuring a novel butterfly unit and an efficient modular polynomial multiplier. The proposed accelerator utilizes a radix-4-based configurable NTT design, which is capable of executing both forward and inverse NTT operations on a unified architecture. When implemented on the Xilinx Virtex-7 FPGA platform, the proposed architecture achieves an acceleration of 1.02–2.30 times in terms of latency, a throughput improvement of 1.02–2.30 times, and an area throughput improvement of up to 3.30 times, relative to the prior works.