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.