A computer-implemented method comprising: generating, by a client associated with a target blockchain network , a request for operating client data from the target blockchain network and cross-chain data of one or more blockchain networks different from the target blockchain network, wherein the request for operating cross-chain data comprises one or more smart contract computational logics for operating the cross-chain data and wherein the client cannot read data from, and exchange data with, the one or more blockchain networks different from the target blockchain network; sending, from the client, the request for operating cross-chain data to a smart contract service provider comprising a trusted computation execution environment TEE , wherein the smart contract service provider is off the target blockchain network; receiving , by the smart contract service provider , from the client associated with the target blockchain network , the request for operating cross-chain data of one or more blockchain networks different from the target blockchain network; fetching by the smart contract service provider , client data from the target blockchain; sending , by the smart contract service provider to a data visiting service provider , a request for the cross-chain data; receiving , by the smart contract service provider, the cross-chain data from the data visiting service provider; generating , by the TEE, a result using the client data and the cross-chain data, wherein the result is generated by the TEE executing the smart contract computational logics using the client data and the cross-chain data, independently of the target blockchain network; and returning , by the smart contract service provider, the result to the client. generating, by a client associated with a target blockchain network , a request for operating client data from the target blockchain network and cross-chain data of one or more blockchain networks different from the target blockchain network, wherein the request for operating cross-chain data comprises one or more smart contract computational logics for operating the cross-chain data and wherein the client cannot read data from, and exchange data with, the one or more blockchain networks different from the target blockchain network; sending, from the client, the request for operating cross-chain data to a smart contract service provider comprising a trusted computation execution environment TEE , wherein the smart contract service provider is off the target blockchain network; receiving , by the smart contract service provider , from the client associated with the target blockchain network , the request for operating cross-chain data of one or more blockchain networks different from the target blockchain network; fetching by the smart contract service provider , client data from the target blockchain; sending , by the smart contract service provider to a data visiting service provider , a request for the cross-chain data; receiving , by the smart contract service provider, the cross-chain data from the data visiting service provider; generating , by the TEE, a result using the client data and the cross-chain data, wherein the result is generated by the TEE executing the smart contract computational logics using the client data and the cross-chain data, independently of the target blockchain network; and returning , by the smart contract service provider, the result to the client. <EOS>