| Title: |
Where to Place Your TEE? In Search of a Censorship-Resilient Design for Rollup Sequencers |
| Authors: |
Arusoaie, Andrei; Bărbieru, Claudiu-Nicu; Captarencu, Oana-Otilia; Felber, Pascal; Libert, Corentin; Onica, Emanuel; Rivière, Etienne; Schiavoni, Valerio; Yuhala, Peterson |
| Contributors: |
Andrei Arusoaie and Claudiu-Nicu Bărbieru and Oana-Otilia Captarencu and Pascal Felber and Corentin Libert and Emanuel Onica and Etienne Rivière and Valerio Schiavoni and Peterson Yuhala |
| Publisher Information: |
Schloss Dagstuhl – Leibniz-Zentrum für Informatik |
| Publication Year: |
2026 |
| Collection: |
DROPS - Dagstuhl Research Online Publication Server (Schloss Dagstuhl - Leibniz Center for Informatics ) |
| Subject Terms: |
Rollups; Trusted Execution Environments; Censorship |
| Description: |
Ethereum is the dominant blockchain ecosystem capable of executing Turing-complete smart contracts. Rollups gained significant traction as the primary layer 2 (L2) solution meant to bring horizontal scalability to the main Ethereum network (L1). A core component of any rollup is the sequencer, which creates new L2 blocks to be submitted in rollup batches to L1. In most of the current rollup architectures, this component is centralised. As a result, these designs are prone to inconspicuous censorship practices by the sequencer. Trusted execution environments (TEEs) can guarantee the integrity of various sequencer components, which is instrumental in addressing censorship. However, the reaction of the system design to censorship attempts depends on where a TEE is integrated and which components it protects. In particular, this reaction is limited in the case of a monolithic TEE-protected sequencer design. Proposer-Builder Separation (PBS) is a non-monolithic paradigm adopted on L1, which separates the production of blocks from proposing them for inclusion in the blockchain. Recently, PBS has been considered for integration with L2 sequencers, with an impact on alleviating censorship. In this paper, we explore the design space of TEE-integrating PBS and non-PBS sequencer variants. First, we introduce a formal framework for the censorship actions that captures the specificity of the L2 sequencer. Then, we analyse to what extent the different designs address these censorship actions. Our main contribution is a novel design variation that allows for a precise observation of censored transactions. In the presence of TEEs, in a PBS setting, we demonstrate this precise observability, which is necessary to enable resilience to censorship. |
| Document Type: |
article in journal/newspaper; conference object |
| File Description: |
application/pdf |
| Language: |
English |
| Relation: |
Is Part Of LIPIcs, Volume 361, 29th International Conference on Principles of Distributed Systems (OPODIS 2025); https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2025.27 |
| DOI: |
10.4230/LIPIcs.OPODIS.2025.27 |
| Availability: |
https://doi.org/10.4230/LIPIcs.OPODIS.2025.27; https://nbn-resolving.org/urn:nbn:de:0030-drops-252000; https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2025.27 |
| Rights: |
https://creativecommons.org/licenses/by/4.0/legalcode |
| Accession Number: |
edsbas.2DF89220 |
| Database: |
BASE |