3-Slot-Finality Protocol for Ethereum

TL;DR

This paper introduces a new protocol for Ethereum that significantly reduces finalization time from over 64 slots to just 3 slots, enhancing security and transaction speed during network fluctuations.

Contribution

It proposes a novel 3-slot finality protocol combining a partially synchronous finality gadget with dynamic consensus protocols, improving Ethereum's finality speed and security.

Findings

Achieves finality within three slots after a proposal.

Reduces exposure to reorganizations and MEV exploits.

Maintains safety and liveness during network asynchrony.

Abstract

Gasper, the consensus protocol currently employed by Ethereum, typically requires 64 to 95 slots -- the units of time during which a new chain extending the previous one by one block is proposed and voted -- to finalize. This means that under ideal conditions -- where the network is synchronous, and all chain proposers, along with more than two-thirds of the validators, behave as dictated by the protocol -- proposers construct blocks on a non-finalized chain that extends at least 64 blocks. This exposes a significant portion of the blockchain to potential reorganizations during changes in network conditions, such as periods of asynchrony. Specifically, this finalization delay heightens the network's exposure to Maximum Extractable Value (MEV) exploits, which could undermine the network's integrity. Furthermore, the extended finalization period forces users to balance the trade-off between economic security and transaction speed. To address these issues and speed up finality, we introduce a partially synchronous finality gadget, which we combine with two dynamically available consensus protocols -- synchronous protocols that ensure safety and liveness even with fluctuating validator participation levels. This integration results in secure ebb-and-flow protocols [SP 2021], achieving finality within three slots after a proposal and realizing 3-slot finality.