Paper 2014/105

Reducing the Overhead of Cloud MPC

Ashish Choudhury and Arpita Patra and Nigel P. Smart

Abstract

We present a secure multi-party computation (MPC) protocol in the honest-majority setting, which aims to reduce the communication costs in the situation where there are a large number of parties (as in a cloud scenario). Our goal is to reduce the usage of point-to-point channels, so as to enable the cloud to be used for multiple different protocol executions. We assume that the number of adversarially controlled parties is relatively small, and that an adversary is unable to target the proactive corruption of a subset of the parties (technically we assume a static corruption model for simplicity). As well as enabling a cloud provider to run multiple MPC protocols, our protocol also has highly efficient theoretical communication costs as a general MPC protocol when compared with other protocols in the literature; in particular the communication cost, for circuits of a suitably large depth, is $\Order(|\Circuit| \cdot \kappa^7)$, for security parameter $\kappa$~and circuit size $|\Circuit|$.