In an information processing system and method which enables detection processing of a revoked entity using an enabling key block (EKB), a device or a service provider as a revoked entity is determined on the basis of the enabling key block (EKB) used for key distribution in a tree structure. ID which enables position identification in the hierarchical key distribution tree is stored in a public key certificate and tracing processing using a tag of the enabling key block (EKB) is executed on the basis of the ID acquired from the public key certificate, thus determining whether or not the ID is of a position where EKB processing (decryption) is possible and determining the presence/absence of revocation of an entity corresponding to the ID.