Efficient secure multiparty computation with identifiable abort

Abstract

We study secure multiparty computation (MPC) in the dishonest majority setting providing security with identifiable abort, where if the protocol aborts, the honest parties can agree upon the identity of a corrupt party. All known constructions that achieve this notion require expensive zero-knowledge techniques to obtain active security, so are not practical. In this work, we present the first efficient MPC protocol with identifiable abort. Our protocol has an information-theoretic online phase with message complexity O(n2) for each secure multiplication (where n is the number of parties), similar to the BDOZ protocol (Bendlin et al., Eurocrypt 2011), which is a factor in the security parameter lower than the identifiable abort protocol of Ishai et al. (Crypto 2014). A key component of our protocol is a linearly homomorphic information-theoretic signature scheme, for which we provide the first definitions and construction based on a previous non-homomorphic scheme. We then show how to implement the preprocessing for our protocol using somewhat homomorphic encryption, similarly to the SPDZ protocol (Damgård et al., Crypto 2012).