A processor including hardware and performing control in accordance with an input signal is configured to: read, after the processor is booted, firmware information including an encrypted authentication file and an execution program to be executed by the processor; decrypt the encrypted authentication file with reference to the read encrypted authentication file and key information for decrypting the encrypted authentication file; execute the execution program in the processor when the encrypted authentication file is decrypted; and stop the execution of the execution program in the processor when the decryption of the encrypted authentication file fails.