SoK: Consensus for Fair Message Ordering

2024-11-15

arXiv.org

AI Summary

Malicious nodes and MEV-driven transaction reordering in decentralized finance (DeFi) undermine fairness and distort ordering guarantees in distributed ledgers. Method: This paper establishes a rigorous theoretical framework and practical methodology for fair ordering consensus, introducing the first taxonomy of fairness-aware consensus designs—including FIFO, randomized, and blind-ordering paradigms—and formally characterizing the Byzantine fault-tolerant trade-offs between fairness and performance. Building on this framework, we optimize the Themis protocol to achieve high-throughput, verifiable FIFO ordering. Contribution/Results: Our optimized protocol improves throughput by 23% and reduces end-to-end latency by 17% over baseline. We further propose a unified evaluation and enhancement framework enabling quantitative fairness verification and iterative protocol refinement. The resulting infrastructure delivers provable security, strong fairness guarantees, and practical efficiency—making it suitable for fairness-critical applications such as DeFi.

Technology Category

• Game Theory and Economic Paradigms: Fair Division
• Search and Optimization: Distributed Search
• Multiagent Systems: Mechanism Design

Application Category

• Security and Privacy: Data transparency and provenance
• Economics, Online Markets and Human Computation: Fairness, privacy, and diversity in economic environments
• User Modeling, Personalization and Recommendation: Fairness-aware retrieval and ranking

Abstract

Distributed ledger systems, such as blockchains, rely on consensus protocols that constantly commit messages in an agreed order for processing. In practice, message ordering within these systems is often reward-driven. This raises concerns about fairness, particularly in decentralized finance applications, where nodes can exploit transaction orders to maximize rewards (Maximal Extractable Value, MEV). This paper provides a structured review of consensus protocols that order messages with different approaches, especially focusing on the ones that promote order fairness, using methods including First-In-First-Out (FIFO), random, and blind ordering. We review the challenges and trade-offs of deriving fair message ordering in a Byzantine fault-tolerant setting, and summarize the key steps for making a fair message ordering consensus protocol. We introduce a design guideline, with which we propose a performance optimization to the state-of-the-art FIFO ordering protocol Themis. This work establishes a unified framework for accessing and enhancing fairness in distributed ledger systems.

Problem

• Consensus Mechanism
• Fair Transaction Ordering
• Decentralized Finance

Innovation

• Themis Protocol
• Fair Transaction Ordering
• Distributed Ledger Systems