International Association for Cryptologic Research

International Association
for Cryptologic Research


Broadcast-Optimal Four-Round MPC in the Plain Model

Michele Ciampi , The University of Edinburgh
Ivan Damgård , Aarhus University
Divya Ravi , Aarhus University
Luisa Siniscalchi , Technical University of Denmark
Yu Xia , The University of Edinburgh
Sophia Yakoubov , Aarhus University
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Presentation: Slides
Conference: TCC 2023
Abstract: The prior works of Cohen, Garay and Zikas (Eurocrypt 2020), Damgård, Magri, Ravi, Siniscalchi and Yakoubov (Crypto 2021) and Damgård, Ravi, Siniscalchi and Yakoubov (Eurocrypt 2023) study 2-round Multi-Party Computation (where some form of set-up is required). Motivated by the fact that broadcast is an expensive resource, they focus on so-called broadcast optimal MPC, i.e., they give tight characterizations of which security guarantees are achievable, if broadcast is available in the first round, the second round, both rounds, or not at all. This work considers the natural question of characterizing broadcast optimal MPC in the plain model where no set-up is assumed. We focus on 4-round protocols, since 4 is known to be the minimal number of rounds required to securely realize any functionality with black-box simulation. We give a complete characterization of which security guarantees, (namely selective abort, selective identifiable abort, unanimous abort and identifiable abort) are feasible or not, depending on the exact selection of rounds in which broadcast is available.
  title={Broadcast-Optimal Four-Round MPC in the Plain Model},
  author={Michele Ciampi and Ivan Damgård and Divya Ravi and Luisa Siniscalchi and Yu Xia and Sophia Yakoubov},