Maximal extractable value (MEV) in which block proposers unethically gain profits by manipulating the order in which transactions are included within a block, is a key challenge facing blockchains such as Ethereum today. Left unchecked, MEV can lead to a centralization of stake distribution thereby ultimately compromising the security of blockchain consensus. To preserve proposer decentralization (and hence security) of the blockchain, Ethereum has advocated for a proposer-builder separation (PBS) in which the functionality of transaction ordering is separated from proposers and assigned to separate entities called builders. Builders accept transaction bundles from searchers, who compete to find the most profitable bundles. Builders then bid completed blocks to proposers, who accept the most profitable blocks for publication. The auction mechanisms used between searchers, builders and proposers are crucial to the overall health of the blockchain. In this paper, we consider PBS design in Ethereum as a game between searchers, builders and proposers. A key novelty in our design is the inclusion of future block proposers, as all proposers of an epoch are decided ahead of time in proof-of-stake (PoS) Ethereum within the game model. Our analysis shows the existence of alternative auction mechanisms that result in a better (more profitable) equilibrium to players compared to state-of-the-art. Experimental evaluations based on synthetic and real-world data traces corroborate the analysis. Our results highlight that a rethinking of auction mechanism designs is necessary in PoS Ethereum to prevent disruption.

翻译：最大可提取价值（MEV）是指区块提议者通过操纵交易在区块内的排序以不道德地获利，这是当今以太坊等区块链面临的关键挑战。若不加以约束，MEV将导致权益分配集中化，最终危及区块链共识的安全性。为维护区块链的提议者去中心化（进而保证安全性），以太坊提出了一种提议者-构建者分离（PBS）方案，其中交易排序功能从提议者中剥离，并分配给名为“构建者”的独立实体。构建者接受来自搜索者的交易捆绑包，这些搜索者竞相寻找利润最高的捆绑包。随后，构建者将完成的区块竞标提交给提议者，后者则选择最具盈利性的区块进行发布。搜索者、构建者与提议者之间的拍卖机制对区块链的整体健康至关重要。本文将以太坊中的PBS设计视为搜索者、构建者与提议者之间的博弈。我们设计的一个关键创新在于纳入了未来区块提议者——因为在权益证明（PoS）以太坊中，每个纪元的所有提议者均会提前确定。分析表明，存在替代性拍卖机制，能使参与者达到比现有最优方案更优（更有利可图）的均衡。基于合成数据与真实数据轨迹的实验评估验证了这一分析。我们的结果强调，在PoS以太坊中，必须重新思考拍卖机制设计以防止系统性失衡。