Method of sending an executable code to a reception device and method of executing this code

A process for sending an executable code to a security module locally connected to a receiving device, this security module including a microcontroller and a memory, said memory including at least one executable area provided to contain instructions suitable to be executed by said microcontroller, and at least one non-executable area, wherein the microcontroller cannot execute the instructions, wherein the process comprises the following steps:

• a) dividing the executable code into blocks;
• b) adding at least one block management code to said blocks, in order to create an extended block, this extended block having a size at the most equal to that of the executable area of the memory;
• c) introducing the content of an extended block in a message of the type to be processed in the receiving device, in such a way that the whole executable code is contained in a plurality of messages;
• d) sending a message to the receiving device, this message containing one of the extended blocks different from the first extended block, the first extended block containing the start of the executable program;
• e) processing said message in order to extract its extended block;
• f) storing the executable code and said at least one management code of the block received in the executable area of the memory;
• g) executing at least one management code of said extended block, this management code having the effect of transferring the content of the block into a non-executable area of the memory;
• h) repeating the steps d) to g) until all the extended blocks are stored in said non-executable area of the memory, except for the first block;
• i) sending a message containing the first extended block to the receiving device;
• j) processing said message in order to extract its extended block;
• k) storing the executable code of the block received in the executable area of the memory.