A Hardware-Software Co-Design for the Discrete Gaussian Sampling of FALCON Digital Signature

Sampling random values from a discrete Gaussian distribution with high precision is a major and computationally-intensive operation of emerging and existing cryptographic standards. FALCON is one such algorithm that the National Institute of Standards and Technology chose to standardize as a next-generation, quantum-secure digital signature algorithm. The discrete Gaussian sampling of FALCON has both flexibility and efficiency needs–it constitutes 72% of total signature generation in reference software and requires sampling from a variable mean and standard deviation. Unfortunately, there are no prior works on accelerating this complete sampling procedure. In this paper, we propose a hardware-software co-design for accelerating FALCON's discrete Gaussian sampling subroutine. The proposed solution handles the flexible computations for setting the variable parameters in software and executes core operations with low latency, parameterized, and custom hardware. The hardware parameterization allows trading off area vs. performance. On a Xilinx SoC FPGA Architecture, the results show that compared to the reference software, our solution can accelerate the sampling up to 56.05× and the full signature scheme by 1.67×. Moreover, we quantified that our optimized multiplier circuits can improve the throughput over a straightforward implementation by 2.87×.