Broadcast-Optimal Two-Round MPC

Ran Cohen, Juan Garay, Vassilis Zikas

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

9 Scopus citations

Abstract

An intensive effort by the cryptographic community to minimize the round complexity of secure multi-party computation (MPC) has recently led to optimal two-round protocols from minimal assumptions. Most of the proposed solutions, however, make use of a broadcast channel in every round, and it is unclear if the broadcast channel can be replaced by standard point-to-point communication in a round-preserving manner, and if so, at what cost on the resulting security. In this work, we provide a complete characterization of the trade-off between number of broadcast rounds and achievable security level for two-round MPC tolerating arbitrarily many active corruptions. Specifically, we consider all possible combinations of broadcast and point-to-point rounds against the three standard levels of security for maliciously secure MPC protocols, namely, security with identifiable, unanimous, and selective abort. For each of these notions and each combination of broadcast and point-to-point rounds, we provide either a tight feasibility or an infeasibility result of two-round MPC. Our feasibility results hold assuming two-round OT in the CRS model, whereas our impossibility results hold given any correlated randomness.

Original languageEnglish
Title of host publicationAdvances in Cryptology – EUROCRYPT 2020 - 39th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Proceedings
EditorsAnne Canteaut, Yuval Ishai
PublisherSpringer
Pages828-858
Number of pages31
ISBN (Print)9783030457235
DOIs
StatePublished - 2020
Externally publishedYes
Event39th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2020 - Zagreb, Croatia
Duration: 10 May 202014 May 2020

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume12106 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference39th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2020
Country/TerritoryCroatia
CityZagreb
Period10/05/2014/05/20

Bibliographical note

Publisher Copyright:
© International Association for Cryptologic Research 2020.

Funding

Ran Cohen’s research was supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Project Activity (IARPA) under contract number 2019-19-020700009 (ACHILLES). Juan Garay and Vassilis Zikas were supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), via 2019-1902070008. We would like to thank Prabhanjan Ananth, Arpita Patra, and Divya Ravi for useful discussions and comments. We also thank the anonymous reviewers of Eurocrypt 2020 for pointing us to the client-server protocol MPC of [35]. Ran Cohen?s research was supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Project Activity (IARPA) under contract number 2019-19-020700009 (ACHILLES). Juan Garay and Vassilis Zikas were supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), via 2019-1902070008. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, DoI/NBC, or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright annotation thereon. This work was done in part while Vassilis Zikas was visiting the Simons Institute for the Theory of Computing, UC Berkeley, and UCLA.

FundersFunder number
ACHILLES
Simons Institute for the Theory of Computing, UC Berkeley
University of California, Los Angeles
Office of the Director of National Intelligence
Intelligence Advanced Research Projects Activity2019-19-020700009, 2019-1902070008

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