Cross-Chain Asset Bridge with Fraud-Proof Verification

A bridge protocol that lets tokens move between two blockchains, with fraud proofs to catch invalid transfers.

Blockchains cannot talk to each other directly, so moving a token from one chain to another requires a bridge, and bridges have become one of the most attacked parts of the ecosystem, with losses in the hundreds of millions of dollars. The central question is how to move value across chains without trusting a single party. This project designs and builds a bridge that uses fraud proofs to catch invalid transfers.

When a user locks tokens on the source chain, a relayer network reports the event to the destination chain, where an equivalent wrapped token is minted. Instead of trusting every report, the bridge accepts it optimistically and opens a challenge period during which any validator can submit a fraud proof if the report does not match the source chain. A valid challenge cancels the transfer and penalises the dishonest relayer, while an unchallenged transfer finalizes. The contracts are written in Solidity and tested with Hardhat on Ethereum and Polygon test networks. The project includes a security review of the contracts covering re-entrancy, replay attacks and key management, with tests that try to break the design.

You will learn cross-chain messaging, the optimistic security model, incentive design and how to audit smart contracts. The Project Reference Guide includes a security-focused audit write-up, and the Reference Implementation provides the contracts, relayer and test suite.