Fast confirmation, a standard for trusting a block before finality
Strawmap Glamsterdam (Early 2027) · fast confirmation
This work adds to clients a rule that, once enough validator votes have accumulated, judges a block as one that will not be reverted within a few seconds, without waiting for finality after the block attaches to the chain.
Why it is needed
On Ethereum, a block attached to the chain is not immediately final. It cannot be undone until votes accumulate and reach finality, which currently takes two epochs, about 13 minutes. So exchanges, wallets, and bridges have each set up their own standard, such as trusting a block after a few more blocks have passed. These standards have loose grounding. If too conservative, users wait a long time, and if too loose, they can fall victim to a chain reorganization (reorg). Fast confirmation unifies this judgment into a single rule based on consensus research. It looks at the share of validator votes concentrated on a block and the blocks after it, and if it computes that the block can no longer be reverted under the assumption that honest validators are the majority, it marks the block as confirmed. When the network is healthy, the decision usually comes within one or two slots. The consensus rules themselves do not change. This is work for clients to implement the rule and expose it for wallets and apps to use, so the Strawmap puts it in the Glamsterdam column, but it is not a commitment tied to the fork schedule.
How it works
- Votes accumulate When the proposer publishes a block, the validator committee for that slot sends votes (attestations). A vote means supporting this block as the head of the chain.
- Count the share of support The client calculates the share of votes concentrated on this block and the blocks attached after it. It also looks at how many votes could go to a competing branch.
- If it cannot be reverted, confirm Under the assumption that honest validators are the majority and the network is healthy, if it computes that the block would not be displaced even if all the remaining votes went the other way, it marks the block as confirmed.
- Finality stays as it is Fast confirmation is a judgment made at an earlier stage. When finality follows afterward, the block reaches a state where it can no longer be fully reverted.