Authenticating data at a microcontroller using message authentication codes

A method of verifying data at a microcontroller using message authentication codes (MACs), comprising the steps of:

• (a) generating at a microprocessor of the microcontroller a valid message authentication code (MAC) using valid data;
• (b) transmitting the valid MAC to a peripheral of the microcontroller along with the valid data;
• (c) receiving an authentication message at the microprocessor from the peripheral in response to transmitting the valid MAC;
• (d) generating at the microprocessor an invalid MAC, which is created by changing one or more bits of the valid MAC;
• (e) testing the peripheral's MAC verification by transmitting the invalid MAC to the peripheral along with the valid data in response to the authentication message;
• (f) receiving a second authentication message at the microprocessor from the peripheral in response to transmitting the invalid MAC;
• (g) determining whether the peripheral is properly authenticating MACs based on the second authentication message;
• and
• wherein steps (a) and (d) are carried out by the microprocessor in the microcontroller, and wherein in steps (c) and (f) the authentication messages are received by the microprocessor in the microcontroller.