A Deep Dive into Integration Methodologies in RISC-V
Valeria Piscopo, Alessandra Dolmeta, Mattia Mirigaldi, Maurizio Martina, Guido Masera · 2025
The integration methodology can significantly affect the performance of dedicated accelerators.This work explores this aspect, considering Keccak, a pivotal hashing standard in Post-Quantum Cryptography (PQC), as a case of study.The paper presents three versions of KRONOS (Keccak RISC-V Optimized eNgine fOr haShing): a loosely coupled memory-mapped accelerator, a tightly coupled approach, and an Instruction Set Extension (ISE).The latter two versions leverage the Core-V eXtension InterFace (CV-X-IF) interface, with and without, respectively, an additional register file to store the Keccak state.Experimental results demonstrate that the tightly coupled integration achieves the highest throughput-to-area ratio (1.070 Mb/(s•LUTs)), outperforming both the loosely coupled (0.937 Mb/(s•LUTs)) and coprocessor-based (0.386 Mb/(s•LUTs)) implementations.This confirms that a tightly integrated accelerator balances resource consumption and performance most effectively.