Temporary relay: A more flexible way to cross chains

As blockchain technology advances, cross-chain asset transfer has become a critical issue in achieving interoperability between different blockchain networks. However, existing cross-chain solutions often require high trust requirements and complex communication protocols, which hinder usability and flexibility. To address these issues, this work introduces the temporary relay, a novel cross-chain asset transfer model without continuous blockchain network presence and frequent inter-chain communication. Technically, the temporary relay uses non-interactive zero-knowledge proofs to verify transactions and protect privacy while ensuring blockchain immutability and traceability after the temporary relay is shut down. We detail the construction of the temporary relay and analyze the security of the circuits constructed by the zero-knowledge proofs. Prototype implementation on the Substrate blockchain platform and experimental evaluation demonstrate the feasibility of the temporary relay. Furthermore, the verification time of zero-knowledge proofs in our model is short.