HE^2: A Communication-Light Heterogeneous Architecture for Efficient Fully Homomorphic Encryption
This work addresses the significant computational and memory overheads of CKKS fully homomorphic encryption, which have limited existing ASIC or near-memory acceleration approaches due to high hardware costs, low efficiency, and severe heterogeneous communication latency. To overcome these challenges, the authors propose HE², a communication-light xPU-xMU heterogeneous acceleration architecture that, for the first time, systematically optimizes ModUp and ModDown operations at the dataflow graph (DFG) level. HE² integrates parallel keyswitch blocks to substantially reduce communication frequency and introduces a group-level pipelined execution mechanism that effectively exploits inter-group parallelism to hide communication latency. Compared to the state-of-the-art accelerator, HE² achieves a 1.66× end-to-end performance improvement, a 9.23× reduction in energy-delay-area product (EDAP), and limits communication stalls to only 6.67% of total execution latency.