Revisiting Higher-Order Masked Comparison for Lattice-Based Cryptography: Algorithms and Bit-Sliced Implementations

Masked comparison is one of the most expensive operations in side-channel secure implementations lattice-based post-quantum cryptography, especially for higher masking orders. First, we introduce two new masked algorithms, which improve arithmetic D’Anvers et al. (2021) and hybrid method Coron respectively. We then look into implementation-specific optimizations, show that small specific adaptations can have a significant impact on overall performance. Finally, implement various state-of-the-art algorithms benchmark them same platform (ARM-Cortex M4) to allow fair between them. with factor $\approx 20\%$ by using Galois Field multiplications 25\%$ streamlining design. Our improvements speedup straightforward implementation 33\%$ . discuss differences provide testing framework ease future research.