Retrieving access data for blockchain networks using highly available trusted execution environments

A non-transitory, computer-readable storage medium storing one or more instructions executable by a computer system to perform operations comprising:

• receiving, from a client smart contract and by a relay system smart contract executing within a blockchain network, a request for retrieving data from an external data source, the request comprising encrypted data, the encrypted data comprising access data for accessing the external data source that is encrypted using a service public key of a key management node that is external to the blockchain network;
• selecting, by the relay system smart contract, a relay system node from a plurality of relay system nodes that are external to the blockchain network, wherein the plurality of relay system nodes are distributed with a service private key of the key management node;
• executing, by the key management node, an attestation process with each of the plurality of relay system nodes and an attestation service, wherein the key management node executes a key distribution process with the plurality of relay system nodes, the key distribution process resulting the service private key of the key management node being distributed to the plurality of relay system nodes;
• transmitting, by the relay system smart contract, the request to the relay system node;
• receiving, from the relay system node and by the relay system smart contract, a return result in response to the request, the return result comprising the data retrieved from the external data source obtained by the relay system node and a digital signature, wherein the digital signature is generated based on the data retrieved from the external data source and the service private key of the key management node;
• and
• transmitting, by the relay system smart contract, the return result to the client smart contract.

A computer-implemented system, comprising:

• one or more computers;
• and
• one or more computer memory devices interoperably coupled with the one or more computers and having tangible, non-transitory, machine-readable media storing one or more instructions that, when executed by the one or more computers, perform one or more operations comprising:
• receiving, from a client smart contract and by a relay system smart contract executing within a blockchain network, a request for retrieving data from an external data source, the request comprising encrypted data, the encrypted data comprising access data for accessing the external data source that is encrypted using a service public key of a key management node that is external to the blockchain network;
• selecting, by the relay system smart contract, a relay system node from a plurality of relay system nodes that are external to the blockchain network, wherein the plurality of relay system nodes are distributed with a service private key of the key management node;
• executing, by the key management node, an attestation process with each of the plurality of relay system nodes and an attestation service, wherein the key management node executes a key distribution process with the plurality of relay system nodes, the key distribution process resulting the service private key of the key management node being distributed to the plurality of relay system nodes;
• transmitting, by the relay system smart contract, the request to the relay system node;
• receiving, from the relay system node and by the relay system smart contract, a return result in response to the request, the return result comprising the data retrieved from the external data source obtained by the relay system node and a digital signature, wherein the digital signature is generated based on the data retrieved from the external data source and the service private key of the key management node;
• and
• transmitting, by the relay system smart contract, the return result to the client smart contract.