One-round finality, finalizing a block with a single vote
Strawmap L* (2029~30) · 1-round finality
This is a consensus design in which a block is irreversibly finalized by a single round of validator voting. Today finality takes two epochs, about 15 minutes, and this research aims to cut that to around one slot.
Why it is needed
Ethereum blocks can still be reverted for a while after they are created. A block is finalized only after enough votes from validators have accumulated, but today there are too many validators for all of them to vote in one slot. So votes are collected spread over one epoch (32 slots), and a block is finalized only after two epochs have passed. That is about 15 minutes. In the meantime exchanges and bridges must wait on deposits, and the risk of a reorg, where the chain briefly forks and then reverts, remains. One-round finality is research into collecting votes once within the slot in which the block is proposed and finalizing immediately. It has been discussed under the name single slot finality on ethresear.ch and elsewhere. To make this possible, techniques for quickly merging a huge number of signatures and ways of handling the validator count are being studied together. With faster finality, users gain confidence within seconds that a transaction will not be reversed. The consensus design, which today mixes two rules, also becomes a single one, which makes security analysis easier. It is a core item of the long-term lean Ethereum goal of making the consensus layer mathematically lighter. The Strawmap places it in the L* cell (2029 to 30), but this is only an estimate and not a confirmed schedule.
How it works
- Block proposal When a slot starts, the proposer builds a new block and broadcasts it to the network. This is the same step as today.
- One vote and signature aggregation Validators vote in favor of this block within the same slot. The technique of merging a huge number of signatures into one to reduce network load is needed here.
- Instant finality If at least two thirds of the total stake votes in favor, the block is finalized on the spot. There is no need to wait several epochs, and the block becomes irreversible immediately.