International Association for Cryptologic Research

International Association
for Cryptologic Research


Round-Optimal Multi-Party Computation with Identifiable Abort

Michele Ciampi , The University of Edinburgh
Divya Ravi , Aarhus University
Luisa Siniscalchi , Aarhus University
Hendrik Waldner , The University of Edinburgh
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Conference: EUROCRYPT 2022
Abstract: Secure multi-party computation (MPC) protocols that are resilient to a dishonest majority allow the adversary to get the output of the computation while, at the same time, forcing the honest parties to abort. Aumann and Lindell introduced the enhanced notion of security with identifiable abort, which still allows the adversary to trigger an abort but, at the same time, it enables the honest parties to agree on the identity of the party that led to the abort. More recently, in Eurocrypt 2016, Garg et al. showed that, assuming access to a simultaneous message exchange channel for all the parties, at least four rounds of communication are required to securely realize non-trivial functionalities in the plain model. Following Garg et al., a sequence of works has matched this lower bound, but none of them achieved security with identifiable abort. In this work, we close this gap and show that four rounds of communication are also sufficient to securely realize any functionality with identifiable abort using standard and generic polynomial-time assumptions. To achieve this result we introduce the new notion of bounded-rewind secure MPC that guarantees security even against an adversary that performs a mild form of reset attacks. We show how to instantiate this primitive starting from any MPC protocol and by assuming trapdoor-permutations. The notion of bounded-rewind secure MPC allows for easier parallel composition of MPC protocols with other (interactive) cryptographic primitives. Therefore, we believe that this primitive can be useful in other contexts in which it is crucial to combine multiple primitives with MPC protocols while keeping the round complexity of the final protocol low.
Video from EUROCRYPT 2022
  title={Round-Optimal Multi-Party Computation with Identifiable Abort},
  author={Michele Ciampi and Divya Ravi and Luisa Siniscalchi and Hendrik Waldner},