Multiple Proposer Transaction Fee Mechanism Design: Robust Incentives Against Censorship and Bribery

TL;DR

The paper develops a game-theoretic framework for designing and evaluating transaction fee mechanisms in multi-proposer blockchain settings with censorship risk and bribery. Extending Roughgarden's TFMs to incomplete information and bribery attacks, it analyzes three TFMs for Fork-Choice Enforced Inclusion Lists (FOCIL): Double TFM, Single TFM, and Single Prioritized TFM. It shows that Double TFM and Single TFM preserve key incentive properties (DSIC, Bayesian-Nash variants) and improve censorship resistance under congestion, while Single Prioritized TFM fails fair-under-congestion. The work provides concrete definitions and proofs, including formalization of bribery functions, types, beliefs, and phase-wise allocations, offering guidance for Ethereum's EIP-1559 and future multi-proposer designs to robustly resist bribery and manipulation under congestion.

Abstract

Censorship resistance is one of the core value proposition of blockchains. A recurring design pattern aimed at providing censorship resistance is enabling multiple proposers to contribute inputs into block construction. Notably, Fork-Choice Enforced Inclusion Lists (FOCIL) is proposed to be included in Ethereum. However, the current proposal relies on altruistic behavior, without a Transaction Fee Mechanism (TFM). This study aims to address this gap by exploring how multiple proposers should be rewarded to incentivize censorship resistance. The main contribution of this work is the identification of TFMs that ensure censorship resistance under bribery attacks, while also satisfying the incentive compatibility properties of EIP-1559. We provide a concrete payment mechanism for FOCIL, along with generalizable contributions to the literature by analyzing 1) incentive compatibility of TFMs in the presence of a bribing adversary, 2) TFMs in protocols with multiple phases of transaction inclusion, and 3) TFMs of protocols in which parties are uncertain about the behavior and the possible bribe of others.

Figures (2)

• Figure 1: Overview of the FOCIL mechanism. thiery2024eip7805
• Figure 2: Model Phases. In the first phase, users, includers, and the block producer send transactions to the mempool $M$. Transactions originating from the includers and the block producer are referred to as fake. In the second phase, includers create inclusion lists with transactions from the mempool M and/or fake transactions issued by themselves during this phase. In the third phase, the block producer constructs their block including transactions from the mempool M, the inclusion lists and/or fake transactions issued by themselves during this phase. The sets $F^{Init}_{BP}, F^{Init}_j$ include the fake transactions submitted by the block producer and includer $j$ respectively during the first phase. $M_0$ is the set with transactions sent by the users. $F_j$ is the set with the fake transactions includer $j$ adds directly (without sending to the mempool) to their inclusion list and $F_{BP}$ the set with the fake transactions the block producer includes directly in their block.

Theorems & Definitions (38)

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