Proof of History (PoH)
Overview
Proof of History (PoH) is a novel cryptographic mechanism introduced by Anatoly Yakovenko for the Solana blockchain. It acts as a decentralized clock, allowing validator nodes to verify the passage of time and the chronological order of transactions without needing to communicate with each other.
Under the Hood
PoH leverages a sequential hashing function (specifically SHA-256) running continuously on a single CPU core. Since each hash requires a predictable amount of time to execute, the output of the function creates a verifiable proof of time elapsed, creating an immutable sequence of events.
Impact on Performance
By establishing the order of transactions before the consensus layer is reached, PoH reduces the overhead and network communication delays typical of blockchains like Ethereum. This enables Solana to process tens of thousands of transactions per second with sub-second block times.