REVOCATION OF CERTIFICATES AND EXCLUSION OF OTHER SUBJECTS IN DRM SYSTEM BASED ON REVOCATION LIST FROM DELEGATED REVOCATION AUTHORITY

摘要

PURPOSE: Revocation of certificates and exclusion of other subjects in a DRM system based on a revocation list from a delegated revocation authority are provided to inform the DRM system that a digital certificate or other subject of the DRM system is not credible any more. CONSTITUTION: It is judged that a revocation requirement is present in the certificate(401). If one of the requirements appoints a position for obtaining the revocation list, the revocation list is obtained from the position(405). It is ensured that the revocation list has an issuance time satisfying a freshness requirement fixed to the revocation list described in the certificate(407). If one of the requirements appoints a public key for a signer of the revocation list, it is judged that the matched revocation list is present(409). If the matched revocation list is present, the revocation list is used by assuming that the revocation list has the issuance time satisfying the freshness requirement fixed to the requirement for the certificate(411).