A computer-implemented method for authenticating a unified blockchain domain name, UBCDN, of a blockchain instance in a Unified Blockchain Network, UBN, wherein the UBN includes a plurality of blockchain instances that are communicatively linked by two or more relays, the method comprising: obtaining, by a computing system, a UBCDN message (440a, 440b) of the blockchain instance, wherein the UBCDN message comprises: a digital signature (446a, 446b) of an owner of the UBCDN of the blockchain instance (a UBCDN owner) on the UBCDN; a domain certificate (448a, 448b) of the UBCDN; and the UBCDN of the blockchain instance, wherein the UBCDN is recognizable globally by all blockchain instances in the UBN, and wherein the UBCDN comprises: a blockchain domain name (310, 442a, 442b) of the blockchain instance, wherein the blockchain domain name is a unique identifier of the blockchain instance in a unified blockchain network, wherein the blockchain domain name comprises a human-readable label, and a chain identifier (320, 444a, 444b) of the blockchain instance uniquely corresponding to the blockchain domain name, wherein the chain identifier indicates a blockchain network configuration of the blockchain instance; wherein the domain certificate of the UBCDN comprises: the blockchain domain name of the blockchain instance; a public key of the UBCDN owner; and a digital signature of a trusted certificate authority, CA, on the blockchain domain name of the blockchain instance and the public key of the UBCDN owner; verifying whether the domain certificate of the UBCDN is issued by the CA using a public key of the CA; and verifying whether the UBCDN is issued by the UBCDN owner using the public key of the UBCDN owner. obtaining, by a computing system, a UBCDN message (440a, 440b) of the blockchain instance, wherein the UBCDN message comprises: a digital signature (446a, 446b) of an owner of the UBCDN of the blockchain instance (a UBCDN owner) on the UBCDN; a domain certificate (448a, 448b) of the UBCDN; and the UBCDN of the blockchain instance, wherein the UBCDN is recognizable globally by all blockchain instances in the UBN, and wherein the UBCDN comprises: a blockchain domain name (310, 442a, 442b) of the blockchain instance, wherein the blockchain domain name is a unique identifier of the blockchain instance in a unified blockchain network, wherein the blockchain domain name comprises a human-readable label, and a chain identifier (320, 444a, 444b) of the blockchain instance uniquely corresponding to the blockchain domain name, wherein the chain identifier indicates a blockchain network configuration of the blockchain instance; a digital signature (446a, 446b) of an owner of the UBCDN of the blockchain instance (a UBCDN owner) on the UBCDN; a domain certificate (448a, 448b) of the UBCDN; and the UBCDN of the blockchain instance, wherein the UBCDN is recognizable globally by all blockchain instances in the UBN, and wherein the UBCDN comprises: a blockchain domain name (310, 442a, 442b) of the blockchain instance, wherein the blockchain domain name is a unique identifier of the blockchain instance in a unified blockchain network, wherein the blockchain domain name comprises a human-readable label, and a chain identifier (320, 444a, 444b) of the blockchain instance uniquely corresponding to the blockchain domain name, wherein the chain identifier indicates a blockchain network configuration of the blockchain instance; a blockchain domain name (310, 442a, 442b) of the blockchain instance, wherein the blockchain domain name is a unique identifier of the blockchain instance in a unified blockchain network, wherein the blockchain domain name comprises a human-readable label, and a chain identifier (320, 444a, 444b) of the blockchain instance uniquely corresponding to the blockchain domain name, wherein the chain identifier indicates a blockchain network configuration of the blockchain instance; wherein the domain certificate of the UBCDN comprises: the blockchain domain name of the blockchain instance; a public key of the UBCDN owner; and a digital signature of a trusted certificate authority, CA, on the blockchain domain name of the blockchain instance and the public key of the UBCDN owner; the blockchain domain name of the blockchain instance; a public key of the UBCDN owner; and a digital signature of a trusted certificate authority, CA, on the blockchain domain name of the blockchain instance and the public key of the UBCDN owner; verifying whether the domain certificate of the UBCDN is issued by the CA using a public key of the CA; and verifying whether the UBCDN is issued by the UBCDN owner using the public key of the UBCDN owner.