LEAF: Lightweight and Efficient Hardware Accelerator for Signature Verification of FALCON

Along with the National Institute of Standards and Technology (NIST) post-quantum cryptography (PQC) standardization process, efficient hardware acceleration for PQC has become a priority. Among the NIST-selected PQC digital signature schemes, FALCON shows great promise due to its compact key sizes and efficient Signature Verification procedure. However, FALCON is regarded as highly computationally complex, and as a result, few works for hardware acceleration of FALCON can be found in the literature, where the few existing ones only target high-performance. To fill the gap, this paper presents a Lightweight and Efficient hardware accelerator for the Signature Verification portion of FALCON (LEAF), specifically for resource-constrained applications. We propose an efficient design strategy, including a novel data dependence flow, to maximize the utilization of very small resources for all arithmetic procedures. Then, the proposed full-hardware LEAF is built, containing an ultra-lightweight number theoretical transform (NTT) core with a novel twiddle factor access pattern. Finally, we conduct a thorough evaluation to demonstrate the efficiency of LEAF. To the best of our knowledge, this is the first lightweight and meanwhile most resource-efficient FALCON Signature Verification full-hardware accelerator in the literature, offering 65% and 66% less aggregate resource usage and achieving 24% and 14% less equivalent area-time product (eATP), compared to the state-of-the-art for FALCON-512 and FALCON-1024, respectively. We hope that this work can spur further research in the field.