Validity Proof
A cryptographic proof submitted with every rollup batch that mathematically guarantees the new state was computed correctly.
This is the mechanism behind ZK-rollups. Instead of assuming a batch is honest and waiting for someone to challenge it, the sequencer generates a succinct proof that the math checks out. The base chain verifies the proof and accepts the result immediately. No challenge window, no waiting days to withdraw.
The trade is computational. Producing these proofs is expensive and historically required specialized circuits, which made supporting general smart contracts hard. ZK-SNARKs and ZK-STARKs are the two main proof types. Their cost has fallen sharply since 2023 as proving systems and hardware improved.
Related terms
A rollup that posts a cryptographic validity proof for every batch, giving near-instant finality on the base chain.
Fraud ProofA challenge that lets anyone prove a rollup posted an invalid state update, triggering a rollback on the base chain.
ZK-SNARKA compact cryptographic proof that confirms a statement is true while revealing nothing about the underlying data.
ZK-STARKA zero-knowledge proof system that needs no trusted setup and stays secure against quantum attacks, at the cost of larger proofs.