Paper 2008/414 Original: eprint.iacr.org/2008/414 ↗

On the Number of Synchronous Rounds Required for Byzantine Agreement

Matthias Fitzi
Jesper Buus Nielsen
Abstract

Byzantine agreement is typically considered with respect to either a fully synchronous network or a fully asynchronous one. In the synchronous case, either $t+1$ deterministic rounds are necessary in order to achieve Byzantine agreement or at least some expected large constant number of rounds. In this paper we examine the question of how many initial synchronous rounds are required for Byzantine agreement if we allow to switch to asynchronous operation afterwards. Let $n=h+t$ be the number of parties where $h$ are honest and $t$ are corrupted. As the main result we show that, in the model with a public-key infrastructure and signatures, $d+O(1)$ deterministic synchronous rounds are sufficient where $d$ is the minimal integer such that $n-d>3(t-d)$. This improves over the $t+1$ necessary deterministic rounds for almost all cases, and over the exact expected number of rounds in the non-deterministic case for many cases.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Preprint.
History
2008-10-02: last updated
2008-10-02: published
Short URL
https://ia.cr/2008/414
License
https://creativecommons.org/licenses/by/4.0/

BibTeX

@misc{cryptoeprint:2008/414,
      author = {Matthias Fitzi and Jesper Buus Nielsen},
      title = {On the Number of Synchronous Rounds Required for Byzantine Agreement},
      howpublished = {Cryptology {ePrint} Archive, Paper 2008/414},
      year = {2008},
      url = {https://eprint.iacr.org/2008/414}
}
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