A first authentication-supporting server for a Single Sign On (SSO) service using a Public Key Infrastructure (PKI) based on blockchain networks, comprising:
- at least one memory that stores instructions;
- and
- at least one processor configured to execute the instructions to perform:
- (I) (I-1) if information on requesting a registration of a first user certificate using a first PKI certificate generated through a first app of a user device is acquired from the user device or from another device connected with the user device, a process of transmitting a request for a first signature value to the first app of the user device, wherein the first app has been installed in the user device and allows use of a first service provided by a first service server, and wherein the first signature value is obtained by signing a first verification value for reference with a first private key of the first PKI certificate, (I-2) if the first signature value is acquired from the user device or from another device connected with the user device, a process of verifying or supporting another device connected with the first authentication-supporting server to verify the first signature value, and (I-3) if the first signature value is determined as valid, a process of registering or supporting another device connected with the first authentication-supporting server to register the first user certificate in the first blockchain network, wherein the first user certificate includes a first public key of the first PKI certificate and first registration information thereon;
- (II) (II-1) if it is confirmed that a second user certificate is not registered in a second blockchain network in response to a request for confirming the second user certificate by using a second app of the user device, and if information on requesting a verification of the first user certificate is acquired from a second authentication-supporting server connected with a second service server, a process of confirming or supporting another device connected with the first authentication-supporting server to confirm the first user certificate registered in the first blockchain network, wherein the second app has been installed in the user device and allows use of a second service provided by the second service server, and wherein the second user certificate is registered in the second blockchain network as corresponding to the second app, and (II-2) a process of allowing the second app to transmit a request for a second signature value to the first app, by transmitting or supporting another device connected with the first authentication-supporting server to transmit a result on verifying the first user certificate including a second verification value for reference to the second app of the user device through the second authentication-supporting server connected with the second service server, wherein the second signature value is obtained by signing the second verification value for reference with the first private key of the first PKI certificate;
- and (III) (III-1) if the second signature value is obtained from the first app of the user device or from another device connected with the user device, a process of verifying or supporting the first blockchain network or another device connected with the first authentication-supporting server to verify the second signature value, (III-2) if the second signature value is determined as valid, by transmitting or allowing another device connected with the first authentication-supporting server to transmit a result on verifying the second signature value to the first app of the user device, (III-2-a) a process of supporting the first app of the user device to transmit the result on verifying the second signature value to the second app of the user device, so as to allow the second app to generate a second PKI certificate and transmit information on requesting a registration of the second user certificate using the second PKI certificate to the second authentication-supporting server, (III-2-b) a process of supporting the second authentication-supporting server to transmit a request for a third signature value to the second app in response to the information on requesting the registration of the second user certificate, wherein the third signature value is obtained by signing a third verification value with a second private key of the second PKI certificate, (III-2-c) if the third signature value is acquired from the user device or from another device connected with the user device, a process of supporting the second authentication-supporting server to verify or to allow the second blockchain network or another device connected with the second authentication-supporting server to verify the third signature value, and (III-2-d) if the third signature value is determined as valid, a process of supporting the second authentication-supporting server to register the second user certificate in the second blockchain network, wherein the second user certificate includes a second public key of the second PKI certificate and second registration information thereon.