Abstract: The aim of the present invention is to limit the impact of security breaches, which are the emulators of the security module. This aim is reached by a processing unit of audio/video digital conditional access data, encrypted by control words, responsible for processing security messages containing at least one cryptogram relative to a control word and one instruction relative to the control word, characterized in that it includes means to receive at least two micro programs by security messages, executable by the security module, said security module comprising means to store at least two micro programs and means to receive an instruction contained in the security message, for selecting the micro program indicated by the instruction, for executing the said micro program with at least the cryptogram as a parameter of execution, this execution allowing the calculation of the control word to be sent back to the audio/video processing unit.

Abstract: One embodiment of the present invention discloses a process for sending an executable code to a security module locally connected to a receiving device. This security module comprises a microcontroller and a memory, the memory including at least one executable area provided to contain instructions suitable to be executed by the microcontroller, and at least one non-executable area, wherein the microcontroller cannot execute the instructions. The process includes dividing the executable code into blocks; adding at least one block management code to the blocks in order to create an extended block; introducing the content of an extended block into a message to be processed in the receiving device, in such a way that the whole executable code is contained in a plurality of messages; and sending a message to the receiving device, this message containing one of the extended blocks different from the first extended block.

Abstract: One embodiment of the present invention discloses a process for sending an executable code to a security module locally connected to a receiving device.

Abstract: The aim of the present invention is to limit the impact of security breaches, which are the emulators of the security module. This aim is reached by a processing unit of audio/video digital conditional access data, encrypted by control words, responsible for processing security messages containing at least one cryptogram relative to a control word and one instruction relative to the control word, characterised in that it includes means to receive at least two micro programs by security messages, executable by the security module, said security module comprising means to store at least two micro programs and means to receive an instruction contained in the security message, for selecting the micro program indicated by the instruction, for executing the said micro program with at least the cryptogram as a parameter of execution, this execution allowing the calculation of the control word to be sent back to the audio/video processing unit.