Paper 2023/689

Abraxas: Throughput-Efficient Hybrid Asynchronous Consensus

Erica Blum, University of Maryland, College Park
Jonathan Katz, University of Maryland, College Park
Julian Loss, CISPA Helmholtz Center for Information Security
Kartik Nayak, Duke University
Simon Ochsenreither, Saarland University

Protocols for state-machine replication (SMR) often trade off performance for resilience to network delay. In particular, protocols for asynchronous SMR tolerate arbitrary network delay but sacrifice throughput/latency when the network is fast, while partially synchronous protocols have good performance in a fast network but fail to make progress if the network experiences high delay. Existing hybrid protocols are resilient to arbitrary network delay and have good performance when the network is fast, but suffer from high overhead (``thrashing'') if the network repeatedly switches between being fast and slow (e.g., in a network that is typically fast but has intermittent message delays). We propose Abraxas, a generic approach for constructing a hybrid protocol based on any protocol $\Pi_\mathsf{fast}$ and any asynchronous protocol $\Pi_\mathsf{slow}$ to achieve (1)~security and performance equivalent to $\Pi_\mathsf{slow}$ under arbitrary network behavior; (2)~performance equivalent to $\Pi_\mathsf{fast}$ when conditions are favorable. We instantiate Abraxas with the best existing protocols for $\Pi_\mathsf{fast}$ (Jolteon) and $\Pi_\mathsf{slow}$ (2-chain VABA), and show experimentally that the resulting protocol significantly outperforms Ditto, the previous state-of-the-art hybrid protocol.

Note: Added comparison table

Available format(s)
Cryptographic protocols
Publication info
State Machine ReplicationAsynchronyHybrid Protocol
Contact author(s)
erblum @ umd edu
jkatz2 @ gmail com
loss @ cispa de
kartik @ cs duke edu
s ochsenreither @ gmail com
2023-11-26: revised
2023-05-15: received
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      author = {Erica Blum and Jonathan Katz and Julian Loss and Kartik Nayak and Simon Ochsenreither},
      title = {Abraxas: Throughput-Efficient Hybrid Asynchronous Consensus},
      howpublished = {Cryptology ePrint Archive, Paper 2023/689},
      year = {2023},
      note = {\url{}},
      url = {}
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