SoK: Speedy Secure Finality
Yash Saraswat, Abhimanyu Nag
TL;DR
The paper analyzes the latency gap between execution and finality in Ethereum's Gasper and surveys the fast-finality landscape. It lays out the theoretical primitives (sleepy model, reorganization resilience) and practical architectures (Goldfish, RLMD-GHOST) leading to single-slot and three-slot finality concepts. Through a critical assessment of safety, liveness, and resource-adaptivity trade-offs, it argues that 3-Slot Finality (3SF) currently offers the most viable balance for Ethereum, contingent on solving the signature aggregation bottleneck. The work provides a principled, framework-driven evaluation of fast finality proposals and illuminates the engineering and security challenges that must be tackled for near-instantaneous finality in permissionless networks.
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.