Patent ID: 8315382

Claim:
A method for monitoring an execution of a sequence of instructions of a data processing program in a security module associated to a multimedia unit, the multimedia unit being in communication with a managing center configured for supplying control messages authorizing the multimedia unit to access broadcast audio video content data streams, the security module comprising at least one processor configured for executing the data processing program instructions, a memory, a monitoring module configured for analyzing the instructions before execution by the processor and for verifying the result of the analysis by comparison with reference data, the method comprising: generating, by a security module emulator at the managing center, at least one reference data set by executing the sequence of instructions induced by data of a given control message in the data processing program used by the security module of the multimedia unit; appending, by the managing center, the reference data set into the control message; sending, by the managing center, the control message to the multimedia unit with a stream of access controlled audio video content data; receiving, by the multimedia unit, the control message; loading, by the multimedia unit, the control message into the security module; extracting and storing in a memory the reference data set appended into the control message by the managing center; launching, by the security module, the data processing program including a command activating the monitoring module; analyzing instructions in the data processing program according to a sequence defined by parameters associated to the command; generating, by the monitoring module, a check data set resulting from the analysis of the sequence of instructions; comparing the check data set with the stored reference data set extracted from the control messages; and sending instructions, by the monitoring module, to the security module processor, the instructions determining, according to a result of the comparison, further execution by the processor of the data processing program.