Method for loading a code of at least one software module in a main memory by a security processor, wherein the security processor executes: - a boot code that loads, in the main memory, the code of a boot loader then launches the execution of this boot loader from the main memory, the boot code being recorded in a non-volatile read-only memory of the processor from the first address to which an ordinal counter of the processor points immediately after it is rebooted, then - the code of the boot loader in order to load, in the main memory, the code of a multitasking operating system, then launch the execution of this operating system from this main memory, this operating system being configured to define the user space in a limited range of addresses in the main memory, - the operating system in order to schedule the simultaneous execution of a plurality of user programs by this processor, wherein: - before launching of the execution of the boot loader, the boot code, executed by the processor, verifies the authenticity of the code of the boot loader from a signature of this code and a cryptographic key, and launches the execution of this boot loader only if the code is authentic, - the boot loader also loads, in the main memory, the code of the software module, before launching of the execution of the operating system, in a range of addresses in the main memory that is situated outside of said limited range of addresses, - when it is executed, the boot loader configures a security coprocessor, present inside the integrated circuit of the processor, so that it verifies the authenticity of the code of the software module on the basis of a signature supplied with the code of this module and of a cryptographic key, - after launching of the execution of the operating system, the security coprocessor automatically verifies, at a predefined interval, the authenticity of the loaded code of the software module, and the execution of the software module is prevented if said code is not authentic, this coprocessor to this end using its own non-volatile memory and its own random access memory to execute this verification of the authenticity of the code of the software module without using the main memory, this non-volatile memory and this random access memory being accessible only to the security coprocessor, and - after it is launched, the operating system redirects a request for this software module from a user program to the address in the main memory where the code of this software module was loaded before launching of the execution of the operating system, using a specific file system of the operating system that automatically associates the address of the software module in the virtual memory space of the user program with the physical address of the software module in the main memory. - a boot code that loads, in the main memory, the code of a boot loader then launches the execution of this boot loader from the main memory, the boot code being recorded in a non-volatile read-only memory of the processor from the first address to which an ordinal counter of the processor points immediately after it is rebooted, then - the code of the boot loader in order to load, in the main memory, the code of a multitasking operating system, then launch the execution of this operating system from this main memory, this operating system being configured to define the user space in a limited range of addresses in the main memory, - the operating system in order to schedule the simultaneous execution of a plurality of user programs by this processor, - before launching of the execution of the boot loader, the boot code, executed by the processor, verifies the authenticity of the code of the boot loader from a signature of this code and a cryptographic key, and launches the execution of this boot loader only if the code is authentic, - the boot loader also loads, in the main memory, the code of the software module, before launching of the execution of the operating system, in a range of addresses in the main memory that is situated outside of said limited range of addresses, - when it is executed, the boot loader configures a security coprocessor, present inside the integrated circuit of the processor, so that it verifies the authenticity of the code of the software module on the basis of a signature supplied with the code of this module and of a cryptographic key, - after launching of the execution of the operating system, the security coprocessor automatically verifies, at a predefined interval, the authenticity of the loaded code of the software module, and the execution of the software module is prevented if said code is not authentic, this coprocessor to this end using its own non-volatile memory and its own random access memory to execute this verification of the authenticity of the code of the software module without using the main memory, this non-volatile memory and this random access memory being accessible only to the security coprocessor, and - after it is launched, the operating system redirects a request for this software module from a user program to the address in the main memory where the code of this software module was loaded before launching of the execution of the operating system, using a specific file system of the operating system that automatically associates the address of the software module in the virtual memory space of the user program with the physical address of the software module in the main memory.