Patent ID: 7577253
Filing Date: 2009-08-18
Classification: G06Q,G07F,H04N

Abstract:
1. A method of providing conditional access to an encrypted data stream, the method comprising: receiving encrypted content data at a stream receiving device, the decryption of which requires temporally changing control words (CW), in a data stream; receiving first decryption control messages (ECM's) in the data stream, each first decryption control message (ECM) containing at least one of the control words that is required for decrypting the encrypted content data; receiving second decryption control message (EMM's) which contain management information for entitling selected stream receiving devices to decrypt the encrypted content data from the data stream using control words from the first decryption control messages (ECM's); receiving further management information included in at least part of the first decryption control messages (ECM's) at random based upon a random generator, contained in at least one of source providers, for supplying said management information; extracting a control word from at least one of the first decryption control message (ECM) from the stream; together with said extracting, testing whether the at least one first decryption control message (ECM) contains further management information targeted at the stream receiving device; and indefinitely disabling subsequent decryption of at least part of the stream in the stream receiving device upon detection of said testing, wherein said further management information specifies a condition upon entitlement data, said testing comprising searching for entitlement data stored in said stream receiving device to detect whether any of the searched entitlement data meets said condition, and performing said disabling if such entitlement data with specified said condition of disabling is found.