Ring-LWE on 8-Bit AVR Embedded Processor

Abstract

Fast implementation of Ring-LWE is a challenge for the low-end embedded processors. One of the most expensive operation for Ring-LWE is Number Theoretic Transform (NTT). Many works have investigated the optimized implementation for the NTT operation. In this paper, we further optimized the NTT operation on the low-end 8-bit AVR microcontrollers. We focused on the optimized and secure polynomial multiplication to ensure countermeasures against timing attacks and high performance. In particular, we propose the combined Look-Up Table (LUT) based fast reduction techniques in regular fashion. With the optimization techniques, the proposed NTT implementation enhances the performance by 14.6% than previous best results. Finally, proposed NTT implementations are applied to the Ring-LWE key scheduling and encryption operations, which require the only 1,325,171 and 1,430,601 clock cycles for 256-bit security levels.