A Fast Confirmation Rule (aka Fast Synchronous Finality) for the Ethereum Consensus Protocol

TL;DR

This paper introduces a new fast confirmation rule for Ethereum that significantly reduces transaction finality time from around 13-19 minutes to approximately 12 seconds under certain network conditions.

Contribution

The paper proposes a novel confirmation rule for Ethereum's consensus protocol that leverages synchrony assumptions to achieve rapid transaction finality, improving over existing methods.

Findings

Achieves 12-second confirmation time under synchrony conditions

Provides a flexible confirmation rule based on network assumptions

Improves transaction finality latency compared to Gasper's FFG

Abstract

A Confirmation Rule, within blockchain networks, refers to an algorithm implemented by network nodes that determines (either probabilistically or deterministically) the permanence of certain blocks on the blockchain. An example of Confirmation Ruble is the Bitcoin's longest chain Confirmation Rule where a block $b$ is confirmed (with high probability) when it has a sufficiently long chain of successors, its siblings have notably shorter successor chains, the majority of the network's total computation power (hashing) is controlled by honest nodes, and network synchrony holds. The only Confirmation Rule currently available in the Ethereum protocol, Gasper, is the FFG Finalization Rule. While this Confirmation Rule works under asynchronous network conditions, it is quite slow for many use cases. Specifically, best-case scenario, it takes around 13 to 19 min to confirm a transaction, where the actual figure depends on when the transaction is submitted to the network. In this work, we devise a Fast Confirmation Rule for Ethereum's consensus protocol. Our Confirmation Rule relies on synchrony conditions, but provides a best-case confirmation time of 12 seconds only, greatly improving on the latency of the FFG Finalization Rule. Users can then rely on the Confirmation Rule that best suits their needs depending on their belief about the network conditions and the need for a quick response.