Solana's Alpenglow Protocol Targets Sub-Second Finality With New Certificate System

Solana's upcoming Alpenglow consensus protocol replaces the current vote-based finality model with a certificate system using aggregated BLS signatures, aiming to confirm transactions in hundreds of milliseconds rather than the 12-plus seconds required today. A block reaches finality once 60% of staked validators sign the same message, while an 80% threshold enables single-round fast finality. The protocol's design assumes a maximum network message latency of 250 milliseconds, and a leader producing no block is now skipped after 800 milliseconds — down from 1.4 seconds as of a June 29, 2026 update. These figures are protocol design targets derived from the validator source code and have not yet been measured on Solana's mainnet, as the Alpenglow activation gate had not triggered at the time of writing.