Paper 2019/270

Sync HotStuff: Simple and Practical Synchronous State Machine Replication

Ittai Abraham, Dahlia Malkhi, Kartik Nayak, Ling Ren, and Maofan Yin


Synchronous solutions for Byzantine Fault Tolerance (BFT) can tolerate up to minority faults. In this work, we present Sync HotStuff, a surprisingly simple and intuitive synchronous BFT solution that achieves consensus with a latency of $2\Delta$ in the steady state (where $\Delta$ is a synchronous message delay upper bound). In addition, Sync HotStuff ensures safety in a weaker synchronous model in which the synchrony assumption does not have to hold for all replicas all the time. Moreover, Sync HotStuff has optimistic responsiveness, i.e., it advances at network speed when less than one-quarter of the replicas are not responding. Borrowing from practical partially synchronous BFT solutions, Sync HotStuff has a two-phase leader-based structure, and has been fully prototyped under the standard synchrony assumption. When tolerating a single fault, Sync HotStuff achieves a throughput of over 280 Kops/sec under typical network performance, which is comparable to the best known partially synchronous solution.

Available format(s)
Publication info
Preprint. MINOR revision.
Distributed computingblockchainsconsensus protocolsSMRSynchrony
Contact author(s)
kartik1507 @ gmail com
2020-05-04: last of 6 revisions
2019-03-12: received
See all versions
Short URL
Creative Commons Attribution


      author = {Ittai Abraham and Dahlia Malkhi and Kartik Nayak and Ling Ren and Maofan Yin},
      title = {Sync HotStuff: Simple and Practical Synchronous State Machine Replication},
      howpublished = {Cryptology ePrint Archive, Paper 2019/270},
      year = {2019},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.