Validity Proof

A validity proof is a cryptographic proof, submitted alongside a batch of layer-2 transactions, showing that the new state was computed correctly from the previous one. The layer-1 contract checks the proof mathematically, so it never has to trust the operator or re-run the transactions itself. This is what defines a ZK rollup: because correctness is proven up front, withdrawals back to layer 1 can settle as soon as a proof is accepted, without the multi-day challenge window that optimistic rollups need. Note that validity covers execution, not intent — a proof confirms the rules were followed, not that a contract is well designed or that the sequencer ordered your transaction fairly.