Patent ID: 8782417
Filing Date: 2014-07-15
Classification: H04N

Abstract:
1. A method for secure processing of access controlled audio/video data by a processing unit comprising a first conditional access device connected to a second conditional access device provided with a descrambler and a secured processor or secured hardware logic, said processing unit receiving encrypted control messages, the method comprises steps of: receiving a control message by the first conditional access device, said control message being made up of a first part including first access conditions and of a second part structured as a control message including at least second access conditions and a control word; decrypting the control message with a common key specific to processing units having a first conditional access device and verifying an authenticity of said control message with first authentication data associated to the control message; verifying the first access conditions of the control message in relation to a first right stored in a rights database included in the processing unit and when the verification is successful; transmitting the second part and a second right retrieved from the rights database to the second conditional access device, said second right being encrypted by a personal key embedded in the second conditional access device and associated to a signature made up of a message authentication code encrypted with the personal key, said second right being ignored by the first conditional access device; decrypting, by the second conditional access device, the second part with a common key specific to processing units having a second conditional access device and verifying an authenticity of said second part with second authentication data associated to the second part; verifying the second access conditions of the second part in relation to the second right previously verified with the signature by using the personal key embedded in the second conditional access device, and when the verification is successful, releasing and loading the control word into the descrambler; and descrambling by the descrambler the access controlled audio/video data by using the control word and providing said audio/video data in clear to an appropriate output of the processing unit.