Patent ID: 8549655

Claim:
A method for secure processing of access controlled audio/video data by a processing unit receiving control messages, the control messages comprising at least one first control word and first right execution parameters, at least one second control word and second right execution parameters, said processing unit being connected to a first access control device, the method comprising the steps of: verifying, by the first access control device, the first right execution parameters by comparison with rights stored in a memory associated to said first access control device and when the verification is successful; extracting from the control message a block comprising the first control word, the second control word and the second right execution parameters; obtaining and transmitting the first control word to a deciphering module of access controlled audio/video data integrated into the processing unit; storing said first control word in said deciphering module; transmitting, by the first access control device, at least the second right execution parameters to a second access control device integrated into the processing unit; executing, by the second access control device, instructions included in the second right execution parameters using data stored in a memory associated to said second access control device to obtain the second control word; storing the second control word in the deciphering module; and deciphering, by the deciphering module, access controlled audio/video data packets by using the first control word during a crypto-period and the second control word during a following crypto-period.