Reducing Communication Channels in MPC

We show that the recent, highly efficient, three-party honest-majority computationally-secure MPC protocol of Araki et al. can be generalised to an arbitrary \(Q_2\) access structure. Part of the performance of the Araki et al. protocol is from the fact it does not use a complete communication network for the most costly part of the computation. Our generalisation also preserves this property. We present both passively- and actively-secure (with abort) variants of our protocol. In all cases we require fewer communication channels for secure multiplication than Maurer’s “MPC-Made-Simple” protocol for \(Q_2\) structures, at the expense of requiring pre-shared secret keys for Pseudo-Random Functions.