High-Speed and Low-Complexity Modular Reduction Design for CRYSTALS-Kyber

In the process of NIST post-quantum cryptography standardization, CRYSTALS-Kyber (Kyber) was selected as one of the first four candidates to be standardized for its strong security and excellent performance. Towards the computation-intensive modular reduction operation of Kyber, this paper proposes a high-speed and low-complexity modular reduction algorithm based on the signed number representation and the proposed Fast Look-Up Table (FLUT). FPGA experiment results demonstrate that our design costs nearly 25% fewer hardware resources and 25% shorter critical path than the state-of-the-art reduction design for Kyber. Moreover, the computational complexity of Inverse Number Theoretic Transform (INTT), a primary function of Kyber, is reduced using the property of our reduction algorithm.