SMBHA: A System-Level Multicore BGV Hardware Accelerator Based on FPGA

Fully homomorphic encryption (FHE) enables calculations on encrypted data and is a crucial foundation for achieving privacy computing. However, the high computation overhead restricts its widespread application. Even after algorithm and software optimization, its processing speed remains low. This article proposes the first practical system-level multicore Brakerski-Gentry-Vaikuntanathan (BGV) hardware acceleration scheme based on field-programmable gate array (FPGA). By analyzing the bottleneck of system acceleration, a hierarchical storage structure is introduced to reduce data movement. A novel 4-2 mixed-radix number theoretic transform (NTT) algorithm is proposed, allowing flexible switching between radix-4 and radix-2, with the ability to reuse twiddle factors. In addition, a reconfigurable processing element (PE) is proposed that supports all homomorphic operations of BGV. The design of this article is evaluated on Xilinx Virtex7 series FPGA, achieving a throughput of NTT/inverse NTT (INTT) up to $14\times $ higher than previous designs. Compared with simple encrypted arithmetic library (SEAL), the full system performances of homomorphic encryption (ENC), decryption (DEC), and homomorphic multiplication achieve improvements of $13.9\times $ , $7.07\times $ , and $16.6\times $ , respectively.