Photonic accelerator boosts encrypted computing speed fivefold
PHAT: PHotonic Accelerator for TFHE
Cryptography and SecurityHardware ArchitectureEmerging Technologies
Summary
Fully Homomorphic Encryption (FHE) lets people do calculations on data without seeing the data itself, which is great for privacy. A special type called TFHE can do many types of calculations but is very slow because it needs a lot of complex math called FFT. The authors built a new photonic (light-based) device called PHAT to make these calculations much faster by using special memory technology and tailored data handling. This new approach runs TFHE tasks more than twice as fast as the best existing hardware, making encrypted cloud computing more practical.
What this means in practice
- •For cloud infrastructure engineers: Speed up privacy-preserving encrypted computations in cloud servers handling sensitive data.
- •For hardware accelerator designers: Develop new hardware devices using optical memory tech to accelerate complex encrypted data operations.
Authors
Guowei Yang, Farbin Fayza, Beren Aydoğan, Carlos A. Ríos Ocampo, Ayse K. Coskun, Ajay Joshi
Abstract
Fully Homomorphic Encryption (FHE) enables secure computation on encrypted data, making it a promising solution for privacy-preserving applications in the cloud. Among various FHE schemes, FHE over the Torus (TFHE) stands out due to its support for arbitrary operations. However, its high computation and communication overhead, particularly in the Fast Fourier Transform (FFT) operations required during bootstrapping, limits its practicality for real-world applications. Conventional electronic accelerators struggle to achieve sufficient throughput due to the limitations of technology scaling and the memory-wall problem. To address these challenges, we propose PHAT, a PHotonic Accelerator for TFHE leveraging Optically-addressed Phase-Change Memory (OPCM). OPCM-based processing-in-memory systems offer high computation and communication throughput, making them well-suited for accelerating FFT operations in TFHE. However, directly mapping FFT to OPCM presents challenges such as high-precision analog computation and the high latency and energy cost of programming OPCM cells. To overcome these challenges, we introduce a novel electro-photonic accelerator architecture optimized for TFHE, featuring OPCM-based FFT units, a twiddle-stationary dataflow tailored for OPCM, and a scheduling mechanism to maximize the utilization of the FFT units. PHAT delivers $2.14\times$--$5.10\times$ speedup across four real-world TFHE workloads against the state-of-the-art ASIC accelerator. Our approach significantly enhances the performance of TFHE applications, paving the way for practical and efficient homomorphic encryption in cloud computing.