The Pessimistic Proof on Polygon's AggLayer is a new zero-knowledge proof mechanism intended to enable secure and trustworthy cross-chain interoperability. It cryptographically verifies that any withdrawal claim made by a chain connected to AggLayer is completely backed by deposits made into the unified bridge contract on Ethereum (L1), preventing chains from withdrawing more funds than they have put.
How It Works
1. Verification of Chain modifications: It validates that each connected chain’s state modifications are done correctly according to its internal accounting and state transition functions
2. Ensuring Withdrawal Collateralization: It ensures that no chain seeks to withdraw tokens it does not have, preserving the integrity of token balances between chains.
Benefits
1. Enhanced Security: By thoroughly checking every cross-chain transaction, it reduces fraud risks and assures that all withdrawals are authentic.
2. Trustless Interoperability: Chains with various security models can successfully interact without trusting one other's internal processes.
3. Flexibility: Chains can accept pessimistic proofs and then upgrade to zero-knowledge verification if required, giving a modular and developer-friendly method
How agglayer generates a pessimistic proof
1.Chains update correctly
2. Chains perform their internal accounting correctly—e.g. a chain doesn’t try to withdraw tokens it doesn’t have
3. All chains have performed correct internal accounting