Patent ID: 6990583

Claim:
A public-key-encryption data-communication system comprising: a public-key-certificate issuer authority for issuing a public key certificate corresponding to a subject to be certificated, the subject performing data transfer using public key encryption; a root registration authority for executing mutual data transfer with said public-key-certificate issuer authority, said root registration authority performing certification of the subject when the subject is under the control of said root registration authority and requesting said public-key-certificate issuer authority to issue the public key certificate corresponding to the subject; and a registration authority for executing mutual data transfer with said root registration authority, said registration authority performing certification of the subject when the subject is under the control of said registration authority and requesting said root registration authority to issue the public key certificate corresponding to the subject, wherein at least one of said root registration authority and said registration authority possesses a revocation list concerning public key certificates corresponding to subjects which are under the control of said at least one, and said at least one executes the updating of said revocation list including the issuance data and time, the next data and time, and the version information.