OFHE: An Electro-Optical Accelerator for Discretized TFHE

TL;DR

OFHE is an electro-optical accelerator that significantly improves the efficiency and throughput of Discretized TFHE homomorphic encryption operations, enabling faster and more power-efficient encrypted computations.

Contribution

It introduces OFHE, a novel electro-optical accelerator that supports DTFHE operations with enhanced latency, throughput, and power efficiency compared to prior TFHE accelerators.

Findings

8.7% reduction in DTFHE operation latency

57% increase in DTFHE operation throughput

94% improvement in throughput per Watt

Abstract

This paper presents \textit{OFHE}, an electro-optical accelerator designed to process Discretized TFHE (DTFHE) operations, which encrypt multi-bit messages and support homomorphic multiplications, lookup table operations and full-domain functional bootstrappings. While DTFHE is more efficient and versatile than other fully homomorphic encryption schemes, it requires 32-, 64-, and 128-bit polynomial multiplications, which can be time-consuming. Existing TFHE accelerators are not easily upgradable to support DTFHE operations due to limited datapaths, a lack of datapath bit-width reconfigurability, and power inefficiencies when processing FFT and inverse FFT (IFFT) kernels. Compared to prior TFHE accelerators, OFHE addresses these challenges by improving the DTFHE operation latency by 8.7\%, the DTFHE operation throughput by $57\%$, and the DTFHE operation throughput per Watt by $94\%$.