Authentication system, spare key management device, spare key management method and spare key management program

摘要

PROBLEM TO BE SOLVED: To restore a key online when a user using a Web service loses a key.SOLUTION: A spare key keeping server 3, on receiving a registration request of a spare public key K3 and a secret key K4 by a terminal 1 from a Web service server 2, generates the spare public key K3 and the secret key K4, to cause to store into a storage unit, transmits the spare public key K3 to the Web service server 2 to cause to store. After the registration of the spare public key K3 and the secret key K4, when the reregistration of the public key K1 and the secret key K2 to be used for key authentication is requested from a terminal 1 not storing a secret key to be used for the key authentication, the spare key keeping server 3 encrypts the request using the spare secret key K4 stored in the storage unit, to transmit to the Web service server 2. According to the request decrypted using the spare public key K3, the Web service server 2 causes the terminal 1 to generate the public key K1 and the secret key K2 to be used for key authentication.SELECTED DRAWING: Figure 1