Patent ID: 8380985

Claim:
A certificate validation method for validating a certificate in a certificate validation server connected to a plurality of terminal devices and a plurality of certificate authorities according to a request from one of the plurality of the terminal devices, wherein said certificate validation server performs a processing operation comprising the steps of: acquiring and storing in a storage unit certificates of relevant certificate authorities among the plurality of certificate authorities, relevant first certificate status information and relevant second certificate status information; building a certification path and validating the certification path by use of the certificates of the relevant certificate authorities, the relevant first certificate status information and the relevant second certificate status information stored in said storage unit; detecting a key update of a given certificate authority of the relevant certificate authorities during the building of the certification path and updating the certificates of the relevant certificate authorities, the relevant first certificate status information and the relevant second certificate status information; and detecting compromise of the given certificate authority during the validation of the certification path and updating the certificates of the relevant certificate authorities, the relevant first certificate status information and the relevant second certificate status information, all of which is stored in the storage unit.