Flexible Byzantine fault tolerance

Dahlia Malkhi, Kartik Nayak, Ling Ren

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

This paper introduces Flexible BFT, a new approach for BFT consensus solution design revolving around two pillars, stronger resilience and diversity. The first pillar, stronger resilience, involves a new fault model called alive-but-corrupt faults. Alive-but-corrupt replicas may arbitrarily deviate from the protocol in an attempt to break safety of the protocol. However, if they cannot break safety, they will not try to prevent liveness of the protocol. Combining alive-but-corrupt faults into the model, Flexible BFT is resilient to higher corruption levels than possible in a pure Byzantine fault model. The second pillar, diversity, designs consensus solutions whose protocol transcript is used to draw different commit decisions under diverse beliefs. With this separation, the same Flexible BFT solution supports synchronous and asynchronous beliefs, as well as varying resilience threshold combinations of Byzantine and alive-but-corrupt faults. At a technical level, Flexible BFT achieves the above results using two new ideas. First, it introduces a synchronous BFT protocol in which only the commit step requires to know the network delay bound and thus replicas execute the protocol without any synchrony assumption. Second, it introduces a notion called Flexible Byzantine Quorums by dissecting the roles of different quorums in existing consensus protocols.

Original languageEnglish (US)
Title of host publicationCCS 2019 - Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security
PublisherAssociation for Computing Machinery
Pages1041-1053
Number of pages13
ISBN (Electronic)9781450367479
DOIs
StatePublished - Nov 6 2019
Event26th ACM SIGSAC Conference on Computer and Communications Security, CCS 2019 - London, United Kingdom
Duration: Nov 11 2019Nov 15 2019

Publication series

NameProceedings of the ACM Conference on Computer and Communications Security
ISSN (Print)1543-7221

Conference

Conference26th ACM SIGSAC Conference on Computer and Communications Security, CCS 2019
Country/TerritoryUnited Kingdom
CityLondon
Period11/11/1911/15/19

Keywords

  • Byzantine Fault Tolerance
  • Distributed computing
  • Synchrony

ASJC Scopus subject areas

  • Software
  • Computer Networks and Communications

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