The ISC International Journal of Information Security

Abstract Kyber, a key encapsulation mechanism (KEM), plays a pivotal role in post-quantum cryptography. As a finalist in the NIST project, Kyber is gaining traction in industry libraries and systems. The heart of the Kyber algorithm lies in the Number Theoretic Transform (NTT), where modular multiplication is the most intricate operation. In this paper, we propose a novel general modular multiplier that reduces both time and area requirements compared to prior methods. Our key innovation lies in the novel reduction algorithm, which avoids fixed values for coefficients A or B (i.e., C = A × B mod q) used in NTT, Inverse NTT (INTT), and PWM (Point-Wise Multiplication). Additionally we introduce two pipeline architectures for modular multiplication within Kyber, emphasizing low area usage and high frequency. These architectures demonstrate 8% and 31% better frequency, while our work achieves the lowest slice usage and AT (Area × Time) among all previous work.