Execution process of binary code of function secured by microprocessor

A method of execution of a binary code of a secure function by a microprocessor, the method comprising:

• a) the recording in a main memory at an address @j of a code line, this code line containing:
• a datum Dj to be processed by the microprocessor or a cryptogram of datum Dj, and
• a first error-detecting code making it possible to detect an error in the datum Dj or in its cryptogram if this datum Dj or its cryptogram is modified after its recording in the main memory,
• at least one of the datum Dj, of its cryptogram and of the first error-detecting code being encrypted as a function of an initialization vector ivj, this initialization vector ivj varying as a function of the address @j at which the code line is recorded according to a relation ivj=Fiv(@j), where the function Fiv is a preprogrammed function of a securing hardware module of the microprocessor which associates a different initialization vector ivj with each different address @j of the main memory,
• b) during the execution of the binary code by the microprocessor, the method comprises the following operations:
• 1) the execution of a loading instruction by the microprocessor which causes the loading into the registers of the microprocessor of the code line recorded at the address @j, and then
• 2) the securing hardware module calculates the initialization vector ivj with the aid of the relation ivj=Fiv(@j), where @j is the address on the basis of which the code line has been loaded, and then
• 3) the securing hardware module decrypts the code line loaded with the aid of the initialization vector ivj calculated to obtain:
• the datum Dj or its cryptogram, and
• the first error-detecting code, and then
• 4) the securing hardware module verifies, with the aid of the first error-detecting code obtained, whether there exists an error in the datum Dj or its cryptogram and, if such an error exists, triggers the signalling of an execution fault and, if such an error does not exist, inhibits this signalling of an execution fault.