Method of securing execution of a program

A method of securing execution of a main program that implements nested functions, the method comprising the steps of:

• executing a security management program arranged to update a list of current functions;
• informing the security management program of a beginning of execution of each function of the main program and updating a list of current functions identifiers;
• informing the security management program of an end of execution of each function;
• after being informed of each end of execution of a function, verifying that the function is indeed the function that was begun the most recently;
• and
• in the event of the verification failing, performing a protection action that is selected as a function of a security level associated with each function,
• wherein the list of functions identifiers is a table comprising a sequence of fields for receiving respective function identifiers, the method comprising the steps of:
• initializing the fields;
• and
• on being informed of the beginning of the execution of a function, writing the identifier of the function in the first available field, and
• wherein the identifier of each function contains a security level associated with the function and the security management program has access to a table associating protection actions that are to be performed according to security levels.