ENCRYPTION/DECRYPTION OF PROGRAM DATA BUT NOT PSI DATA

摘要

A receiver receives a data key from a transmitter. The data key is generated by a random number generator seeded with a seed derived from data to be encrypted in the transmitter. The receiver also receives a synchronizing signal in place of a null packet in an MPEG transport stream, receives encrypted data in the MPEG transport stream, and synchronizes, in response to the received synchronization signal, use of the data key to decrypt the received encrypted data. Additionally or alternatively, an encrypted message having sequential first, second, third, and fourth encrypted portions is decrypted into sequential first, second, third, and fourth decrypted data portions by use of a triple wrap decrypting technique.