Method for securing authentication of a device by a microcontroller

A method for securing authentication of a device by a microcontroller, said microcontroller comprising:

• a package,
• a plurality of leads, extending from inside to outside the package,
• and an electronic chip, placed inside said package, said electronic chip comprising:
• a plurality of pins, some of the pins being electrically connected to the leads of the microcontroller, at least one pin, called the “free” pin, not being connected to a lead and behaving as a passive antenna inside the package, generating a noisy signal that is not accessible outside the package,
• a processing module, configured to generate a recognition signal from the noisy signal generated by said at least one free pin,
• an encryption module connected to the processing module, and configured to encrypt the recognition signal using an encryption key recorded in a memory region of the electronic chip, and
• a communication module, connected to the encryption module, and configured to communicate with the device,
• said device being configured to:
• communicate with the communication module of the electronic chip, and decrypt a signal received by the communication module using a decryption key corresponding to the encryption key of the encryption module of the electronic chip,
• said method comprising:
• detecting, by the microcontroller, of the presence of the device,
• receiving, by the processing module, of the noisy signal not accessible outside the package via the at least one free pin, and generation of the recognition signal based on an operation of processing the received noisy signal,
• encrypting, by the encryption module, of the recognition signal using the encryption key,
• transmitting, by the communication module, of the encrypted recognition signal to the device,
• receiving, by the device, of the encrypted recognition signal and decryption, using the decryption key,
• transmitting, by the device, of the decrypted recognition signal to the microcontroller,
• comparing, by the electronic chip, of the generated recognition signal and of the decrypted recognition signal, and
• authenticating, by the microcontroller, of the device when the decrypted recognition signal corresponds to the generated recognition signal.