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arXiv · 2504.08048

On Quorum Sizes in DAG-Based BFT Protocols

Razya Ladelsky·Roy Friedman
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Abstract

Several prominent DAG-based blockchain protocols, such as DAG-Rider, Tusk, and Bullshark, completely separate between equivocation elimination and committing; equivocation is handled through the use of a reliable Byzantine broadcast black-box protocol, while committing is handled by an independent DAG-based protocol. With such an architecture, a natural question that we study in this paper is whether the DAG protocol would work when the number of nodes (or validators) is only $2f+1$ (when equivocation is eliminated), and whether there are benefits in working with larger number of nodes, i.e., a total of $kf+1$ nodes for $k > 3$. We find that while DAG-Rider's correctness is maintained with $2f+1$ nodes, the asynchronous versions of both Tusk and Bullshark inherently depends on having $3f+1$ nodes, regardless of equivocation. We also explore the impact of having larger number of nodes on the expected termination time of these three protocols.

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Razya Ladelsky, Roy Friedman. 2025-04-10. On Quorum Sizes in DAG-Based BFT Protocols. https://arxiv.org/abs/2504.08048

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