Method of secure management of a memory space for microcontroller

A method of management of an electronic microcontroller system, the microcontroller system including:

• first and second processors, the first processor configured for execution of a non-secure application, exhibiting a non-guaranteed level of functional security and integrity, and a second processor dedicated to execution of a secure application, implementing code and data, and involving a guaranteed level of functional security and integrity, the secure application able to implement a security function;
• and
• means of access to a shared memory space;
• the first processor including a memory management unit configured to implement a check of write-access, to manage write-access to the shared memory space, to be non-modifiable when the secure application implements its security function,
• the management method ensuring check of write-access rendered non-modifiable and comprising:
• apportionment of the shared memory space between a memory area allocated to the secure application and a memory area allocated to the non-secure application;
• implementation of a buffer for anticipation of a translation of the addresses;
• loading into the buffer for anticipation of the translation of the addresses of a set of rules of access to the shared memory space including a rule prohibiting writing by the non-secure application in a reserved area of the memory area allocated to the secure application, the execution of the rule prohibiting writing being checked by the secure application;
• copying into the shared memory space of an image of the buffer for the anticipation of the translation of the addresses;
• loading into the image of the buffer for the anticipation of the translation of the addresses of a rule prohibiting writing in the buffer for the anticipation of the translation of the images;
• implementation, by the memory management unit, of access rules contained in the image of the buffer for the anticipation of the translation of the addresses.