Paper 2026/2029 Original: eprint.iacr.org/2026/2029 ↗

It's Not Just a Phase: Understanding Function Dependence in MPC Preprocessing (Extended Version)

Abstract

Secure multiparty computation (MPC) is a key enabling technology for privacy-preserving applications. To achieve low latency after inputs are provided, many efficient protocols utilize preprocessing, and the landscape of preprocessing approaches is growing and diverse. Some recent works use variants of function-dependent preprocessing, leveraging additional knowledge on the function to be computed for even better performance. While the existing literature primarily focuses on performance, it is mostly overlooked that there exist different kinds of function dependence and what practical implications they have. We systematize the different flavors of function dependence, relating them to practical requirements beyond efficiency.