Sequencer Level Security

Current blockchains lack mechanisms to proactively detect or quarantine malicious transactions, prioritizing decentralization and censorship resistance. Rollups enhance blockchain scalability but typically employ centralized sequencers. This paper introduces Sequencer Level Security (SLS), a protocol empowering rollup sequencers to temporarily quarantine potentially malicious transactions instead of immediately adding them to blocks. We detail the protocol mechanics for transactions from both the rollup mempool and underlying blockchain, addressing trust, decentralization, and security implications. Our prototype implementation atop Geth and the OP stack demonstrates minimal impact on transaction throughput and high accuracy in detecting malicious transactions, illustrating SLS’s practicality and effectiveness. Furthermore, SLS is adaptable to various rollup designs and broader security applications.