Reduced Hierarchy Key Management System and Method

摘要

A controller receives an encrypted media stream (“EMS”) and an identifier indicative of a selected content key from a headend. The EMS is encrypted with an encryption key and can be decrypted with a corresponding decryption key which is determinable from the selected content key. The controller receives indexes and content keys from the headend prior to receiving the EMS. Each index respectively corresponds to an identifier with one index corresponding to the identifier indicative of the selected content key. The content keys correspond to the indexes with one content key corresponding to the index corresponding to the identifier indicative of the selected content key. The controller selects the index corresponding to the identifier indicative of the selected content key upon receiving the EMS, determines the selected content key from the selected index, determines the decryption key from the selected content key, and decrypts the EMS with the decryption key.