Paper 2014/105

Reducing the Overhead of MPC over a Large Population

Ashish Choudhury, Arpita Patra, and Nigel P. Smart

Abstract

We present a secure honest majority MPC protocol, against a static adversary, which aims to reduce the communication cost in the situation where there are a large number of parties and the number of adversarially controlled parties is relatively small. Our goal is to reduce the usage of point-to-point channels among the parties, thus enabling them to run multiple different protocol executions. Our protocol has highly efficient theoretical communication cost when compared with other protocols in the literature; specifically the circuit-dependent communication cost, for circuits of suitably large depth, is $\Order(|\Circuit|\kappa^7)$, for security parameter $\kappa$~and circuit size $|\Circuit|$. Our protocol finds application in cloud computing scenario, where the fraction of corrupted parties is relatively small. By minimizing the usage of point-to-point channels, our protocol can enable a cloud service provider to run multiple MPC protocols.