Efficient Hardware Implementation of the Lightweight CRYSTALS-Kyber

Quantum computing raises questions about the security of data encrypted using modern methods. Hence, the National Institute of Standards and Technology (NIST) has undertaken standardization of post-quantum cryptography (PQC) algorithms to defend against attacks from both classical and quantum computers. Following four rounds of evaluation, CRYSTALS-Kyber has been selected for standardization. In this paper, we present an efficient hardware architecture of CRYSTALS-Kyber for resource-constrained IoT devices. Firstly, we propose a compact hash module for CRYSTALS-Kyber. A single buffer is designed to perform padding, hashing, and holding data. Hence, using large FIFOs for data input/output is eliminated. Then, we propose a novel non-memory-based iterative number theoretic transform (NMI-NTT) architecture. Finally, the data flow between modules is optimized to improve parallelization and execution time. Implementation results on an Artix-7 FPGA show that our design consumes minimal hardware resources compared to the designs reported to date, corresponding to 5487 LUTs, 3426 FFs, 1548 SLICEs, 3.5 BRAMs, and 2 DSPs. Our design computes key generation, encapsulation, and decapsulation phases in 3.3/4.5/6.1 K-cycles for Kyber512, 5.6/7.1/9.2 K-cycles for Kyber768, and 8.5/10.1/12.9 K-cycles for Kyber1024, with 185MHz operating frequency. Our area-time-product (ATP) performance outperforms other designs.