| 摘要 |
Processors that encrypt frames of data representing images and sounds, for example, use a first encryption process to encrypt control data that includes selected data from the data frames and use a second encryption process to encrypt non-selected data from the data frames. The first encryption process is responsive to a key, which may be associated with an intended recipient of the data frames. The second encryption process is responsive to a key that is obtained or derived from the control data. The encrypted control data and the encrypted non-selected data may be delivered to a receiver using separate media. The receiver recovers the data frames using decryption processes that are inverse to the first and second encryption processes. Efficient implementations of the second encryption process are disclosed. |
