by KD.Conway
TL;DR
- This post introduces a Decentralized Anti-MEV Sequencer based on Order-Fairness Byzantine Fault-Tolerant (BFT) Consensus, a mechanism designed to counteract MEV and ensure transaction fairness.
Order Fairness
Received-Order-Fairness[1]: with parameter 1/2 < 𝛾 ≤ 1 dictates that if 𝛾 fraction of honest nodes receive a transaction tx before tx′, then tx should be ordered no later than tx’.
Introducing the Anti-MEV Sequencer
Our proposed solution is a Decentralized Anti-MEV Sequencer that leverages an Order-Fairness Byzantine Fault-Tolerant (BFT) consensus mechanism. This system provides:
Decentralization: Instead of a centralized sequencer, we will build a sequencer network with multiple nodes contributing to transaction ordering and batching.
Order-Fairness: Transactions are processed based on the time they were received by the nodes in the sequencer network, ensuring no one participant can manipulate transaction ordering.
Byzantine Fault Tolerance: The consensus protocol ensures the system remains operational even if some of the participants behave maliciously.
Workflow
When a user wants to send a transaction on a layer 2 blockchain, they submit the transaction to the sequencer network.
The Order-Fairness BFT consensus is employed to determine the correct order of transactions. This guarantees that, even if a minority of nodes act maliciously, the system can still reach consensus on a fair transaction order.
After reaching consensus, the sequencer batches the transactions and submits them to the Rollup smart contract on Ethereum, where they are executed in the agreed-upon order.
For details on the system implementation of the Order-Fairness BFT consensus, please refer to the corresponding references at the end of this post.
References
[1] Kelkar, Mahimna, et al. “Order-fairness for byzantine consensus.” Advances in Cryptology–CRYPTO 2020: 40th Annual International Cryptology Conference, CRYPTO 2020, Santa Barbara, CA, USA, August 17–21, 2020, Proceedings, Part III 40. Springer International Publishing, 2020.
[2] Kelkar, Mahimna, et al. “Themis: Fast, strong order-fairness in byzantine consensus.” Proceedings of the 2023 ACM SIGSAC Conference on Computer and Communications Security. 2023.
