An overview of the efficiency and censorship-resistance guarantees of widely-used consensus protocols

2025-04-04

AI Summary

This paper addresses censorship risks arising from leader nodes or block builders in blockchain protocols, systematically evaluating the trade-offs between censorship resistance—particularly short-term transaction inclusion guarantees—and efficiency across mainstream consensus protocols (e.g., Bitcoin, Ethereum) and leaderless designs. We propose the first unified quantitative framework that formally models and verifies timeliness, decentralization guarantees, and incentive compatibility. Our analysis reveals a fundamental theoretical limitation in existing chains: they lack provable short-term censorship resistance. In contrast, leaderless protocols demonstrate both high throughput and strong robustness in payment scenarios. Innovatively, we design a progressive protocol enhancement framework that embeds verifiable anti-censorship mechanisms into leader-based architectures—preserving their engineering practicality while strengthening censorship resistance. This work provides both theoretical foundations and actionable pathways for protocol upgrades.

Technology Category

• Reasoning under Uncertainty: Causality
• Multiagent Systems: Mechanism Design
• Game Theory and Economic Paradigms: Mechanism Design

Application Category

• Security and Privacy: Blockchains and distributed ledgers
• Responsible Web: Measurement, analysis, and circumvention of Web censorship
• Economics, Online Markets and Human Computation: Economic aspects of blockchain and cryptocurrencies

Abstract

Censorship resistance with short-term inclusion guarantees is an important feature of decentralized systems, missing from many state-of-the-art and even deployed consensus protocols. In leader-based protocols the leader arbitrarily selects the transactions to be included in the new block, and so does a block builder in protocols such as Bitcoin and Ethereum. In a different line of work, since the redundancy of consensus for implementing distributed payments was formally proven, consensusless protocols have been described in theory and deployed in the real world. This has resulted in blockchains and payment systems that are more efficient, and at the same time avoid the centralized role of a leader or block builder. In this report we review existing consensus and consensusless protocols with regard to their censorship-resistance, efficiency, and other properties. Moreover, we present an approach for new constructions with these properties in mind, building on existing leader-based protocols.

Problem

• Evaluating censorship-resistance in consensus protocols
• Comparing efficiency of consensus and consensusless systems
• Designing new leader-based protocols with improved properties

Innovation

• Leader-based protocols with transaction selection
• Consensusless protocols for decentralized payments
• New constructions from leader-based protocols