Overriding production processor authentication restrictions through remote security unit for development code testing

摘要

A device comprises a processor 204 arranged to automatically execute boot code upon start-up or reset. The boot code comprises a code authentication procedure to verify whether additional code is authenticated for execution on the processor. A separate security unit 306 comprises a private unlock key and cryptography logic configured to use the private unlock key to sign a portion of data, thereby generating a signed unlock file for supply to a storage location. The processor is arranged to access the unlock file from the storage location, making it available without requiring connection to the security unit. The unit may be entirely remote from the device, for example under the control of the manufacturer. The boot code further comprises an unlocking authentication procedure configured to check for the unlock file in the storage location and to de-restrict the boot authentication procedure upon verifying the unlock file, therefore allowing less restricted additional code to be authenticated for execution. This allows software developers to test beta versions of code on production processors.