Secure Code Verification for Message Authentication

The patent applies preliminary action by verifying the authenticity of the code (secure boot verification) before performing message authentication. The security device checks whether the code stored in the client device is authentic using cryptographic verification, and only after successful verification does it enable the shared secret key to be used for message authentication. This prevents fake secure boot attacks because the authentication process is blocked at the code verification stage before the MAC generation can be compromised.

The patent introduces a security device as an intermediary component that handles the code verification process. This security device acts as a mediator between the client device and the message authentication process. It verifies the authenticity of the code using cryptographic methods and controls whether the shared secret key can be accessed for MAC generation. By separating the code verification function into a dedicated security device, the patent adds security without significantly complicating the overall system architecture, as the security device operates as a distinct module with a specific function.