## CryptoDB

### Paper: Secure Multiparty Computation with Sublinear Preprocessing

Authors: Ariel Nof , Technion Elette Boyle , IDC Niv Gilboa , Ben-Gurion University Yuval Ishai , Technion Search ePrint Search Google Slides EUROCRYPT 2022 A common technique for enhancing the efficiency of secure multiparty computation (MPC) with dishonest majority is via {\em preprocessing}: In an offline phase, parties engage in an input-independent protocol to securely generate correlated randomness. Once inputs are known, the correlated randomness is consumed by a non-cryptographic'' and highly efficient online protocol. The correlated randomness in such protocols traditionally comes in two flavors: multiplication triples (Beaver, Crypto '91), which suffice for security against semi-honest parties, and {\em authenticated} multiplication triples (Bendlin et al., Eurocrypt '11, Damg{\aa}rd et al., Crypto '12) that yield efficient protocols against malicious parties. Recent constructions of pseudorandom correlation generators (Boyle et al., Crypto '19, '20) enable concretely efficient secure generation of multiplication triples with {\em sublinear communication complexity}. However, these techniques do not efficiently apply to authenticated triples, except in the case of secure two-party computation of arithmetic circuits over large fields. In this work, we propose the first {\em concretely efficient} approach for (malicious) MPC with preprocessing in which the offline communication is {\em sublinear} in the circuit size. More specifically, the offline communication scales with the {\em square root} of the circuit size. From a feasibility point of view, our protocols can make use of any secure protocol for generating (unauthenticated) multiplication triples together with any {\em additive} homomorphic encryption. We propose concretely efficient instantiations (based on strong but plausible linear-only'' assumptions) from existing homomorphic encryption schemes and pseudorandom correlation generators. Our technique is based on a variant of a recent protocol of Boyle et al. (Crypto '21) for MPC with preprocessing. As a result, our protocols inherit the succinct correlated randomness feature of the latter protocol.
##### BibTeX
@inproceedings{eurocrypt-2022-31948,
title={Secure Multiparty Computation with Sublinear Preprocessing},
publisher={Springer-Verlag},
author={Ariel Nof and Elette Boyle and Niv Gilboa and Yuval Ishai},
year=2022
}