Vitalik Backs New Rule to Confirm Ethereum Blocks in 12 Seconds

Ethereum Foundation researcher Julian Ma has proposed the Fast Confirmation Rule (FCR), aiming to reduce deposit times from Ethereum's mainnet to Layer 2 networks and centralized exchanges. The proposal, endorsed by co-founder Vitalik Buterin, targets one of the most persistent friction points in the Ethereum ecosystem: the delay incurred when moving assets.

Under FCR, a block is treated as confirmed once sufficient validator attestations have accumulated - a process that takes roughly 13 seconds under normal network conditions. This mechanism operates below Ethereum's formal finality and rests on two explicit assumptions: the network delivers attestations within approximately 8 seconds, and no single actor controls more than 25% of staked ETH.

FCR stalls if either condition fails, falling back to the finalized head rather than producing an unsafe confirmation. Ma described it as degrading gracefully: 'As soon as sufficiently many attestations are delivered, the block is fast-confirmed.' If FCR's assumptions hold, a fast-confirmed block will be finalized with certainty.

Consensus layer client teams are already working on implementations, which activate via a configuration flag and query the existing JSON-RPC safe tag. Ma estimated an '80-98% reduction' in deposit times for most L2s and exchanges. Buterin called it 'very strong for many use cases.'

Not all observers were convinced. Reviewing the proposal publicly, some developers noted that the 'supermajority honest' assumption carries significant weight. If adversarial stake exceeds 25%, FCR can lose liveness - stalling confirmations entirely, rather than producing incorrect ones.