Enhancing RISC-V Vector Extension for Efficient Application of Post-quantum Cryptography

We present a cryptography extension built on RISC-V Vector Extension for efficient application of lattice-based post-quantum cryptography, offering custom instructions that can perform vectorized operations on polynomials of variable length and data width. We use micro-operation architecture to simplify the execution of variable-latency vector instructions and propose fracturable modular arithmetic units to support operations on variable coefficient width. On this basis, a vector unit is designed, achieving significant speed-up compared to the state-of-the-art counterparts for number-theoretic-transform-based polynomial multiplication. This cryptography extension is further integrated into the gem5 simulator to evaluate CRYSTALS-Kyber and CRYSTALS-Dilithium; results outperform the state-of-the-art implementations with more than 2.3x improvement in cycle count.