Validated Strong Consensus Protocol for Asynchronous Vote-based Blockchains

2024-09-12

AI Summary

Existing BFT consensus protocols for asynchronous blockchain networks suffer from high communication overhead, strong synchrony assumptions, and linear view-change reliance on threshold signatures. Method: This paper proposes a leaderless, synchrony-free, verification-based strongly consistent BFT consensus model with low communication complexity. Contribution/Results: (1) It relaxes the pre-vote agreement requirement among honest nodes and introduces a novel verification-based strong consistency mechanism; (2) it achieves linear view-change in a purely asynchronous model—without threshold signatures—for the first time; (3) it theoretically attains message complexity comparable to partially synchronous protocols such as HotStuff-2. The model guarantees state convergence and continuous chain progression, significantly reducing communication overhead while ensuring rigorous safety and scalability for large-scale deployment.

Technology Category

• Multiagent Systems: Agreement, Argumentation & Negotiation
• Machine Learning: Learning on the Edge & Model Compression
• Constraint Satisfaction and Optimization: Satisfiability Modulo Theories

Application Category

• Security and Privacy: Blockchains and distributed ledgers
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

Vote-based blockchains construct a state machine replication (SMR) system among participating nodes, using Byzantine Fault Tolerance (BFT) consensus protocols to transition from one state to another. Currently, they rely on either synchronous or partially synchronous networks with leader-based coordination or costly Asynchronous Common Subset (ACS) protocols in asynchronous settings, making them impractical for large-scale asynchronous applications. To make Asynchronous SMR scalable, this paper proposes a emph{validated strong} BFT consensus model that allows leader-based coordination in asynchronous settings. Our BFT consensus model offers the same level of tolerance as binary byzantine agreement but does not demand consistency among honest nodes before they vote. An SMR using our model allows nodes to operate in different, tentative, but mutually exclusive states until they eventually converge on the same state. We propose an asynchronous BFT protocol for vote-based blockchains employing our consensus model to address several critical challenges: how to ensure that nodes eventually converge on the same state across voting rounds, how to assure that a blockchain will steadily progress through epochs while reaching consensus for previous epochs, and how to maintain robust byzantine fault tolerance. Our protocol greatly reduces message complexity and is the first one to achieve linear view changes without relying on threshold signatures. We prove that an asynchronous blockchain built on our protocol can operate with the emph{same} simplicity and efficiency as partially synchronous blockchains built on, e.g. HotStuff-2. This facilitates deploying asynchronous blockchains across large-scale networks.

Problem

• Blockchain
• Asynchronous Byzantine Fault Tolerance
• Voting Protocol

Innovation

• Asynchronous Voting
• Efficient Node Rotation
• Strong BFT Model