RVCE-FAL: A RISC-V Scalar-Vector Custom Extension for Faster FALCON Digital Signature

The National Institute of Standards and Technology (NIST) has selected FALCON as one of the standardized digital signature algorithms against quantum attacks in 2022. Compared with the other post-quantum cryptography (PQC) schemes, lattice-based FALCON is more appropriate for future Internet of Things (loT) applications due to the fastest signature verification process and the lowest transmission overhead. In this paper, we propose a custom extension based on the RISC-V scalar-vector framework for efficient implementation of FALCON. To our best knowledge, this work is the first hardware-software co-design for complete FALCON signature generation and verification routines. Besides, we design the first FALCON Gaussian sampling hardware and a RISC-V vector extension (RVV) based domain-specific core. The proposed architecture accelerates kernel operations in FALCON, such as discrete Gaussian sampling, number theoretic transform (NTT), inverse NTT, and polynomial operations. Compared with the reference implementation, results on the gem5-RTL simulation platform present a speedup for signature generation and verification of up to 18 x and 6.9 x.