A High-Performance Domain-Specific Processor With Matrix Extension of RISC-V for Module-LWE Applications

The 5G edge computing infrastructure should be empowered with quantum attack resistance by implementing post-quantum cryptography (PQC). Among various PQC schemes, lattice-based cryptography (LBC) based on learning with error (LWE) has attracted much attention because of its performance efficiency and security guarantee. In LWE-based LBCs, the Module-LWE-based schemes gain advantage over the others benefiting from the unique polynomial matrix and vector structure. To provide a high-performance implementation of Module-LWE applications for the edge computing paradigm, we propose a domain-specific processor based on a matrix extension of RISC-V architecture. This custom extension encapsulates the matrix-based ring operations with a high-level functional abstraction. A 2-D systolic array with configurable functionality is proposed to perform matrix-based number theoretic transform (NTT) and other arithmetic operations, achieving high data-level parallelism with support for the variable-sized polynomial matrix and vector structure. As this structure of Module-LWE involves no data dependency between different inner elements, an out-of-order mechanism is further developed to exploit the instruction-level parallelism. We implement the proposed architecture under TSMC 28nm technology. The evaluation results show that our implementation can achieve up to $3.5\times $ and $3.3\times $ improvement in cycle count respectively in Kyber and Dilithium, compared to the state-of-the-art crypto-processor counterparts.