A Lightweight and Efficient Schoolbook Polynomial Multiplier for Saber

Saber is a lattice-based post-quantum cryptography (PQC) algorithm, which is still a candidate in the 3
^rd
Round of National Institute of Standards and Technology (NIST) PQC standardization process. Saber provides a great advantage of being lightest among all the candidates, so a suitable choice for resource-constraint platforms. Polynomial multiplication occupies most of the resources in hardware implementation of Saber, which needs to be optimized for the efficient hardware implementation. In this work, a lightweight and efficient schoolbook polynomial multiplier is proposed. The architecture includes an efficient multiplication strategy that compute four coefficient-wise multiplication per cycle along with the multiplication operand loading technique being designed for the compact multiplier. The proposed multiplier on Artix-7 FPGA, achieves a frequency of 130 MHz and fits into 201 slices. Compared with the state-of-the-art lightweight schoolbook implementations for Saber, our design has a 30% improved frequency and saves 15.8% of the clock counts at the cost of only 3.7% more LUTs.