Ethereum Fast Confirmation Rule Aims for 12-Second Block Times

Ethereum co-founder Vitalik Buterin has endorsed a new rule that aims to reduce deposit times from the Ethereum mainnet to Layer 2 networks and centralized exchanges. The Fast Confirmation Rule (FCR), proposed by researcher Julian Ma, would confirm blocks in approximately 12 seconds without requiring a hard fork.

Currently, most platforms rely on 'k-deep' confirmation rules, which offer no formal security guarantees. FCR replaces this heuristic with an attestation-based model that counts validator votes rather than blocks.

Under FCR, a block is treated as confirmed once sufficient validator attestations have accumulated. If either of the two explicit assumptions fails, that the network delivers attestations within approximately 8 seconds or that no single actor controls more than 25% of staked ETH, FCR stalls and falls back to finalized head.

Consensus layer client teams are already working on implementations, which require no new API endpoints and no network-wide coordination. Ma described an '80-98% reduction' in deposit times for most L2s and exchanges. Buterin called it 'very strong for many use cases', but some developers raised concerns about the 'supermajority honest' assumption.