International Association
for Cryptologic Research

Traditional notions of secure multiparty computation (MPC) allow mutually distrusting parties to jointly compute a function over their private inputs, but typically do not specify how these inputs are chosen. Motivated by real-world applications where corrupt inputs could adversely impact privacy and operational legitimacy, we consider a notion of authenticated MPC where the inputs are authenticated (for instance, signed using a digital signature) by some certification authority. We propose a generic and efficient compiler that transforms any linear secret sharing based honest-majority MPC protocol into one with input authentication. Our compiler achieves an ideal notion of authenticated MPC equipped with stronger and more desirable security guarantees than those considered in prior works, while incurring significantly lower computational costs and competitive communication overheads when compared to existing solutions. In particular, we entirely avoid the (potentially expensive) protocol-specific techniques and pre-processing requirements that are inherent to these solutions. For certain corruption thresholds, our compiler additionally preserves the stronger identifiable abort security of the underlying MPC protocol. No existing solution for authenticated MPC achieves this regardless of the corruption threshold. Along the way, we make several technical contributions that are of independent interest. This includes the notion of distributed proofs of knowledge and concrete realizations of the same for several relations of interest, such as proving knowledge of many popularly used digital signature schemes, and proving knowledge of opening of a Pedersen commitment.