Paper 2023/1740

Evaluation of Arithmetic Sum-of-Products Expressions in Linear Secret Sharing Schemes with a Non-Interactive Computation Phase

Abstract

Among secure multi-party computation protocols, linear secret sharing schemes often do not rely on cryptographic assumptions and are among the most straightforward to explain and to implement correctly in software. However, basic versions of such schemes either limit participants to evaluating linear operations involving private values or require those participants to communicate synchronously during a computation phase. A straightforward, information-theoretically secure extension to such schemes is presented that can evaluate arithmetic sum-of-products expressions that contain multiplication operations involving non-zero private values. Notably, this extension does not require that participants communicate during the computation phase. Instead, a preprocessing phase is required that is independent of the private input values (but is dependent on the number of factors and terms in the sum-of-products expression).