TOB-SVD: Total-Order Broadcast with Single-Vote Decisions in the Sleepy Model

TL;DR

This paper presents TOB-SVD, a new total-order broadcast protocol for the sleepy model that reduces voting phases and latency, supporting large-scale, dynamic, permissionless systems with Byzantine resilience.

Contribution

TOB-SVD introduces a single-vote, low-latency total-order broadcast protocol resilient to Byzantine faults in the sleepy model, improving scalability and efficiency.

Findings

Requires only one voting phase in the best case

Achieves lower expected latency than existing protocols

Supports up to 1/2 Byzantine validators

Abstract

Over the past years, distributed consensus research has expanded its focus to address challenges in large-scale, permissionless systems, such as blockchains. This shift reflects the need to accommodate dynamic participation, in contrast to the traditional model of a static set of continuously online validators. Works like Bitcoin and the sleepy model have laid the groundwork for this evolving framework. Notable contributions by Momose and Ren (CCS 2022), along with subsequent research, have introduced Total-Order Broadcast protocols that leverage Graded Agreement primitives and support dynamic participation. However, these approaches often require multiple phases of voting per decision, which can create a bottleneck for real-world, large-scale systems. To address this, our paper introduces TOB-SVD, a novel Total-Order Broadcast protocol in the sleepy model that is resilient to up to 1/2 Byzantine validators. TOB-SVD requires only a single phase of voting per decision in the best case and achieves lower expected latency compared to existing approaches offering the same optimal adversarial resilience. This work paves the way for more practical Total-Order Broadcast protocols that can be implemented in real-world systems involving a large number of validators with fluctuating participation over time.