At a transmitter, a program is encrypting according to a one program key, the program key is encrypted, and the encrypted program, the encrypted program key, and non-encrypted PSI data to a receiver are transmitted. At a receiver, the encrypted program, the encrypted program key, and the non-encrypted...http://www.google.de/patents/US8144868?utm_source=gb-gplus-sharePatent US8144868 - Encryption/decryption of program data but not PSI data
