SoK: Speedy Secure Finality

TL;DR

This paper surveys the development of Speedy Secure Finality protocols in blockchain, focusing on reducing confirmation latency in Ethereum while maintaining security, and analyzes the theoretical primitives and practical protocols involved.

Contribution

It introduces core primitives like reorganization resilience and the sleepy model, and analyzes the 3-slot finality protocol as a practical solution.

Findings

Analysis of communication bottlenecks in large validator networks

Development of the generalized sleepy model

Evaluation of 3-slot finality protocol's balance of speed and security

Abstract

While Ethereum has successfully achieved dynamic availability together with safety, a fundamental delay remains between transaction execution and immutable finality. In Ethereum's current Gasper protocol, this latency is on the order of 15 minutes, exposing the network to ex ante reorganization attacks, enabling MEV extraction, and limiting the efficiency of economic settlement. These limitations have motivated a growing body of work on Speedy Secure Finality (SSF), which aims to minimize confirmation latency without weakening formal security guarantees. This paper surveys the state of the art in fast finality protocol design. We introduce the core theoretical primitives underlying this space, including reorganization resilience and the generalized sleepy model, and trace their development from Goldfish to RLMD-GHOST. We then analyze the communication and aggregation bottlenecks faced by single-slot finality protocols in large validator settings. Finally, we survey the 3-slot finality (3SF) protocol as a practical synthesis that balances fast finality with the engineering constraints of the Ethereum network.