Blockchain
Validity proof
Also known as: ZK validity proof, SNARK proof
The cryptographic proof a zk-rollup posts to Layer 1 to prove its state transitions were correct — the zk counterpart to an optimistic fraud proof.
A validity proof is what zk-rollups post to Ethereum L1 to prove that a batch of L2 transactions was executed correctly. Unlike optimistic rollups, which post transactions and rely on a challenge window, zk-rollups prove validity up front via a zk-SNARK or zk-STARK — a cryptographic proof that the L2 state transition function ran correctly.
The L1 smart contract verifies the validity proof algorithmically — no fraud-proof game, no challenge window. If the proof verifies, the state transition is final immediately. Finality for zk-rollups is therefore as fast as the proof-generation time (minutes, typically) rather than the optimistic challenge window (seven days).
LearnCoin anchors on Base, an optimistic rollup — so we rely on fraud proofs, not validity proofs. Both approaches provide the same security guarantee in the long run; the trade-off is finality time versus prover-infrastructure complexity. For a future zk-rollup anchor target, LearnCoin would inherit validity-proof-backed settlement instead of fraud-proof-backed.
Related terms