On the round complexity of randomized byzantine agreement

Ran Cohen, Iftach Haitner, Nikolaos Makriyannis, Matan Orland, Alex Samorodnitsky

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

9 Scopus citations

Abstract

We prove lower bounds on the round complexity of randomized Byzantine agreement (BA) protocols, bounding the halting probability of such protocols after one and two rounds. In particular, we prove that: 1. BA protocols resilient against n/3 [resp., n/4] corruptions terminate (under attack) at the end of the first round with probability at most o(1) [resp., 1/2 + o(1)]. 2. BA protocols resilient against n/4 corruptions terminate at the end of the second round with probability at most 1 − Θ(1). 3. For a large class of protocols (including all BA protocols used in practice) and under a plausible combinatorial conjecture, BA protocols resilient against n/3 [resp., n/4] corruptions terminate at the end of the second round with probability at most o(1) [resp., 1/2 + o(1)]. The above bounds hold even when the parties use a trusted setup phase, e.g., a public-key infrastructure (PKI). The third bound essentially matches the recent protocol of Micali (ITCS’17) that tolerates up to n/3 corruptions and terminates at the end of the third round with constant probability.

Original languageAmerican English
Title of host publication33rd International Symposium on Distributed Computing, DISC 2019
EditorsJukka Suomela
PublisherSchloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing
ISBN (Electronic)9783959771269
DOIs
StatePublished - Oct 2019
Event33rd International Symposium on Distributed Computing, DISC 2019 - Budapest, Hungary
Duration: 14 Oct 201918 Oct 2019

Publication series

NameLeibniz International Proceedings in Informatics, LIPIcs
Volume146
ISSN (Print)1868-8969

Conference

Conference33rd International Symposium on Distributed Computing, DISC 2019
Country/TerritoryHungary
CityBudapest
Period14/10/1918/10/19

Bibliographical note

Publisher Copyright:
© Ran Cohen, Iftach Haitner, Nikolaos Makriyannis, Matan Orland, and Alex Samorodnitsky.

Keywords

  • Byzantine agreement
  • Lower bound
  • Round complexity

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