Multiple Concurrent Proposers: Why and How

2025-09-28

AI Summary

In traditional single-proposer blockchains, validators monopolize transaction inclusion and ordering, enabling extraction of Miner-Extractable Value (MEV). Existing application-layer mitigations rely heavily on on-chain auctions, which require the consensus layer to simultaneously satisfy selective censorship resistance and transaction-content hiding—properties not jointly achieved by prior protocols. Method: We propose the first multi-concurrent-proposer consensus protocol that simultaneously achieves both properties: multiple proposers concurrently submit cryptographically committed transaction bundles; a commit-reveal mechanism ensures content-hiding prior to finalization; and parallel validation guarantees that any valid transaction cannot be selectively delayed. Contribution/Results: Our design fundamentally undermines the root cause of MEV—validator monopoly over transaction ordering—by decentralizing sequencing authority at the consensus layer. Without relying on application-layer auctions, it drastically reduces the exploitable MEV surface while preserving security, fairness, and high throughput.

Technology Category

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

Application Category

• Security and Privacy: Data transparency and provenance
• Economics, Online Markets and Human Computation: Economic aspects of blockchain and cryptocurrencies
• Web Mining and Content Analysis: Web data provenance, reliability, and authenticity

Abstract

Traditional single-proposer blockchains suffer from miner extractable value (MEV), where validators exploit their serial monopoly on transaction inclusion and ordering to extract rents from users. While there have been many developments at the application layer to reduce the impact of MEV, these approaches largely require auctions as a subcomponent. Running auctions efficiently on chain requires two key properties of the underlying consensus protocol: selective-censorship resistance and hiding. These properties guarantee that an adversary can neither selectively delay transactions nor see their contents before they are confirmed. We propose a multiple concurrent proposer (MCP) protocol offering exactly these properties.

Problem

• Addressing miner extractable value in single-proposer blockchains
• Ensuring selective-censorship resistance and hiding properties
• Proposing multiple concurrent proposers to enhance consensus protocol

Innovation

• Multiple concurrent proposers enhance blockchain consensus
• Protocol resists selective censorship and hides transactions
• Reduces miner extractable value without requiring auctions