SynCirc: Efficient Synthesis of Depth-Optimized Circuits for Secure Computation

Abstract

Secure Multi-party Computation (MPC) allows to securely compute on private data. To make MPC practical, logic synthesis can be used to automatically translate a description of the function to be computed securely into optimized and error-free boolean circuits. The work of Demmler et al. (CCS'15) used industry-grade hardware synthesis tools (DC, Yosys) to generate depth-optimized circuits for MPC. To evaluate their optimized circuits, they used the ABY framework (Demmler et al., NDSS'15) for secure two-party computation. The recent ABY2.0 framework (Patra et al., USENIX Security'21) presented round-efficient constructions using multi-input AND gates and improved over ABY by at least 6× in online communication. In this work, we propose SynCirc, an efficient hardware synthesis framework designed for MPC applications. Our framework is based on Verilog and the open-source tool Yosys-ABC. It provides custom libraries and new constraints that accommodate multi-input AND gates. With this, we improve over the work of Demmler et al. by up to 3× in multiplicative depth with a corresponding improvement in online round complexity. Moreover, we provide efficient realizations of several new building blocks including comparison, multiplexers, and equality check. For these building blocks, we achieve improvements in multiplicative depth/online rounds between 22.3% and 66.7%. With these improvements, our framework makes multi-round MPC better-suited for high-latency networks such as the Internet.