HEAX: An Architecture for Computing on Encrypted Data

TL;DR

HEAX is a specialized hardware architecture designed to significantly accelerate Fully Homomorphic Encryption computations, enabling practical use of encrypted data processing with high performance improvements.

Contribution

The paper introduces a novel highly-parallelizable hardware architecture for FHE, including an innovative NTT engine and techniques for end-to-end pipelined design and memory reduction.

Findings

Achieves 164-268x performance improvement over existing solutions

Provides a highly-parallelizable NTT architecture for cryptography

Demonstrates practical hardware implementation for FHE

Abstract

With the rapid increase in cloud computing, concerns surrounding data privacy, security, and confidentiality also have been increased significantly. Not only cloud providers are susceptible to internal and external hacks, but also in some scenarios, data owners cannot outsource the computation due to privacy laws such as GDPR, HIPAA, or CCPA. Fully Homomorphic Encryption (FHE) is a groundbreaking invention in cryptography that, unlike traditional cryptosystems, enables computation on encrypted data without ever decrypting it. However, the most critical obstacle in deploying FHE at large-scale is the enormous computation overhead. In this paper, we present HEAX, a novel hardware architecture for FHE that achieves unprecedented performance improvement. HEAX leverages multiple levels of parallelism, ranging from ciphertext-level to fine-grained modular arithmetic level. Our first contribution is a new highly-parallelizable architecture for number-theoretic transform (NTT) which can be of independent interest as NTT is frequently used in many lattice-based cryptography systems. Building on top of NTT engine, we design a novel architecture for computation on homomorphically encrypted data. We also introduce several techniques to enable an end-to-end, fully pipelined design as well as reducing on-chip memory consumption. Our implementation on reconfigurable hardware demonstrates 164-268x performance improvement for a wide range of FHE parameters.