PQC Cloudization: Rapid Prototyping of Scalable NTT /INTT Architecture to Accelerate Kyber

The advent of quantum computers poses a serious challenge to the security of cloud infrastructures and services, as they can potentially break the existing public-key cryptosystems, such as Rivest-Shamir-Adleman (RSA) and Elliptic Curve Cryptography (ECC). Even though the gap between today's quantum computers and the threats they pose to current public-key cryptography is large, the cloud landscape should act proactively and initiate the transition to the post-quantum era as early as possible. To comply with that, the U.S. government issued a National Security Memorandum in May 2022 that mandated federal agencies to migrate to post-quantum cryptosystems (PQC) by 2035. To ensure the long-term security of cloud computing, it is imperative to develop and deploy PQC resistant to quantum attacks. A promising class of post-quantum cryptosystems is based on lattice problems, which require polynomial arithmetic. In this paper, we propose a scalable number-theoretic transform (NTT) architecture that significantly enhances the performance of polynomial multiplication. Our proposed design exploits multilevels of parallelism to accelerate the NTT computation on reconfigurable hardware. We use the high-level synthesis (HLS) method to implement our design, which allows us to describe the NTT algorithm in a high-level language and automatically generate optimized hardware code. HLS facilitates rapid prototyping and enables us to explore different design spaces and trade-offs on the hardware platforms. Our experimental results show that our design achieves 11× speedup compared to the state-of-the-art requiring only 14 clock cycles for an NTT computation over a polynomial of degree 256. To demonstrate the applicability of our design, we also present a coprocessor architecture for Kyber that utilizes our scalable NTT core.