Patent ID: 7742599

Claim:
A set-top box, comprising: a tuner to receive scrambled content; a CPU; and an integrated circuit to select at least one of a preprogrammed key, internal key, external data and internal data under control of the CPU, comprising: a first cryptographic block to descramble received information using one of an internal key and a preprogrammed key to form one of a descrambled key and descrambled data, a key feedback path to iteratively store the descrambled information as one of an internal key and internal data, and to provide the one of the internal key and the preprogrammed key to a key input of the first cryptographic block and to provide the one of external data and the internal data to a data input of the first cryptographic block, a data feedback path to store the descrambled data within a data register as internal data; data selection logic coupled to the data register and an external information input, the data selection logic to provide one of internal data from the data register and received information from the external information input to a data input of the first cryptographic block, a second cryptographic block to descramble received scrambled digital content using a final descrambling key from the first cryptographic block to form descrambled digital content, and a decoder to decode the descrambled digital content to form clear digital content.