Electronic control device and authentication method

An authentication method executed by a processor of an electronic control device, the electronic control device comprising the processor, a nonvolatile storage device that is electrically data rewritable, and an interface that enables communication with an external data rewriting device, the nonvolatile storage device being set with a hardware ID unique to the electronic control device and a software ID associated with a software program, and the data rewriting device being permitted to rewrite data of the nonvolatile storage device depending on a result of collating the hardware ID with the software ID, the method causing the processor to perform the steps of:

• acquiring, from the nonvolatile storage device in which a software ID for development used during development of the electronic control device and a software ID for mass-production used during mass-production of the electronic control device are set as the software ID, the hardware ID, and the software ID for mass-production, and collating the hardware ID with the software ID for mass-production;
• and when the hardware ID does not conform to the software ID for mass-production, further acquiring the software ID for development from the nonvolatile storage device, and collating the hardware ID with the software ID for development.