Paper 2025/2126

DPaaS: Improving Decentralization by Removing Relays in Ethereum PBS

Abstract

Proposer-Builder Separation (PBS) in Ethereum improves decentralization and scalability by offloading block construction to specialized builders. In practice, MEV-Boost implements PBS via a side-car protocol with trusted relays, resulting in increased centralization as well as security and performance concerns. We propose Decentralized Proposer-as-a-Service (DPaaS), a deployable architecture that eliminates relays while preserving compatibility with Ethereum’s consensus layer. Our insight is that we can reduce centralized trust by distributing the combined roles of the proposer and relay to a set of Proposer Entities (PEs), each running in independent Trusted Execution Environments (TEEs). For compatibility, DPaaS presents itself to Ethereum as a single validator, leveraging the threshold and aggregation properties of the BLS signature scheme used in Ethereum. To decentralize the relay roles (e.g., auctioneer) across TEEs, we developed a new Byzantine broadcast protocol that provides necessary censorship-resistance and availability-backed properties on top of standard consensus. We implemented a prototype of DPaaS and validated it end-to-end on a local Ethereum testnet. Our evaluation, deployed across four independent cloud hosts and driven by real-world traces, shows that DPaaS achieves ≤ 5 ms bid processing latency, 55.69 ms latency from the end of auction to block proposal, and 3% more MEV earnings – demonstrating that DPaaS can offer security and decentralization benefits while providing strong performance.