Security at the sequencer level

Sat, Jun 1, 2024, 02:12 PM · 27:29

The Ethereum consensus protocol defines how transactions are included in blocks. It is accepted as fully decentralized and censorship-resistant, which means that it cannot provide any additional security guarantees to projects built on the Ethereum blockchain. Rollups have been broadly accepted as a promising scaling solution for Ethereum. A common architectural element of every rollup is the sequencer. The sequencer is responsible for collecting transactions from users and includes them in blocks. The ability to alter the rollup sequencing protocol presents a great opportunity to also alter the transaction inclusion rules and enhance them with additional features. This is amplified by the fact that most of the rollup sequencers that are currently used are centrally operated. In this paper, we describe the sequencing protocol of the Zircuit blockchain which includes additional scrutiny from the security perspective for transactions submitted to the sequencer. The protocol does not impose additional centralization that would not be already present in the existing sequencers. It still offers a high degree of censorship resistance, and allows for trustless rederivation of the rollup state. We present the protocol and consider practical aspects and the feasibility of implementing it using the OP stack and the mainstream Ethereum client Geth. The protocol is generic, meaning that it can be used for transaction filtering purposes other than those focused on security.