Bolt-Dumbo Transformer: Asynchronous Consensus As Fast As the Pipelined BFT

Yuan Lu, Zhenliang Lu, Qiang Tang

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

9 Scopus citations


An urgent demand of deploying BFT consensus (e.g., atomic broadcast) over the Internet is raised for implementing (permissioned) blockchain services. The deterministic synchronous protocols can be simple and fast in good network conditions, but are subject to denial-of-service (or even safety vulnerability) when synchrony assumption fails. Asynchronous protocols, on the contrary, are robust against the adversarial network, but are substantially more complicated and slower for the inherent use of randomness. Facing the issues, optimistic asynchronous atomic broadcast (Kursawe-Shoup, 2002; Ramasamy-Cachin, 2005) was proposed to improve the normal-case performance of the slow asynchronous consensus. They run a deterministic fastlane if the network condition remains good, and can fall back to a fully asynchronous protocol via a pace-synchronization mechanism (analog to view-change with asynchronous securities) if the fastlane fails. Unfortunately, existing pace-synchronization directly uses a heavy tool of asynchronous multi-valued validated Byzantine agreement (MVBA). When such fallback frequently occurs in the fluctuating wide-area network setting, the benefits of adding fastlane can be eliminated. We present Bolt-Dumbo Transformer (BDT), a generic framework for practical optimistic asynchronous atomic broadcast. At the core of BDT, we set forth a new fastlane abstraction that is simple and fast, while preparing honest parties to gracefully face potential fastlane failures caused by malicious leader or bad network. This enables a highly efficient pace-synchronization to handle fallback. The resulting design reduces a cumbersome MVBA to a variant of the conceptually simplest binary agreement only. Besides detailed security analyses, we also give concrete instantiations of our framework and implement them. Extensive experiments demonstrate that BDT can enjoy both the low latency of deterministic protocols (e.g., 2-chain version of HotStuff and the robustness of state-of-the-art asynchronous protocols in practice.

Original languageEnglish (US)
Title of host publicationCCS 2022 - Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security
PublisherAssociation for Computing Machinery
Number of pages15
ISBN (Electronic)9781450394505
StatePublished - Nov 7 2022
Externally publishedYes
Event28th ACM SIGSAC Conference on Computer and Communications Security, CCS 2022 - Los Angeles, United States
Duration: Nov 7 2022Nov 11 2022

Publication series

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


Conference28th ACM SIGSAC Conference on Computer and Communications Security, CCS 2022
Country/TerritoryUnited States
CityLos Angeles

All Science Journal Classification (ASJC) codes

  • Software
  • Computer Networks and Communications


  • asynchronous consensus
  • byzantine-fault tolerance
  • optimsitic path


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