HotStuff-1: Linear Consensus with One-Phase Speculation

2024-08-08

arXiv.org

AI Summary

This paper addresses high network latency, leader procrastination, and mutual sabotage by rational participants in Byzantine Fault-Tolerant (BFT) consensus, proposing HotStuff-1. Methodologically: (1) it designs a fault-resilient single-phase speculative finality path, achieving two-hop latency reduction prior to irreversible commitment; (2) it introduces an incentive-compatible dynamic leader rotation and adaptive slotting mechanism to resolve the “prefix speculation dilemma”, simultaneously mitigating procrastination and sabotage; (3) it preserves linear communication complexity. Contributions include: the first BFT protocol jointly achieving low latency, linear message overhead, and rational safety; formal guarantees of safety and liveness under both adversarial and rational attacks; and empirical evaluation demonstrating a two-hop latency reduction without reliance on optimistic assumptions.

Technology Category

• Multiagent Systems: Mechanism Design
• Reasoning under Uncertainty: Other Foundations of Reasoning under Uncertainty
• Natural Language Processing: Safety and Robustness

Application Category

• Responsible Web: Data and user privacy-enhancing technologies for the Web
• Security and Privacy: Data transparency and provenance
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems

Abstract

This paper introduces HotStuff-1, a BFT consensus protocol that improves the latency of HotStuff-2 by two network-hops while maintaining linear communication complexity against faults. Additionally, HotStuff-1 incorporates an incentive-compatible leader rotation regime that motivates leaders to commit consensus decisions promptly. HotStuff-1 achieves a reduction by two network hops by sending clients early finality confirmations speculatively, after one phase of the protocol. Unlike previous speculation regimes, the early finality confirmation path of HotStuff-1 is fault-tolerant and the latency improvement does not rely on optimism. An important consideration for speculation regimes in general, which is referred to as the prefix speculation dilemma, is exposed and resolved. HotStuff-1 embodies an additional mechanism, slotting, that thwarts real-world delays caused by rationally-incentivized leaders. Leaders may also be inclined to sabotage each other's progress. The slotting mechanism allows leaders to drive multiple decisions, thus mitigating both threats, while dynamically adapting the number of allowed decisions per leader to network transmission delays.

Problem

• Reduces consensus latency by two network hops
• Ensures fault-tolerant early finality confirmation
• Mitigates leader-induced delays via slotting mechanism

Innovation

• One-phase speculative early finality confirmation
• Fault-tolerant leader rotation with incentives
• Slotting mechanism for dynamic leader decision limits