Program distribution system, program distribution device, and in-vehicle gateway device

According to a request from a gateway device in a subject vehicle, a program distribution device designates a program that conducts an access to an ECU in the subject vehicle and associated with vehicular information of the subject vehicle on a table where vehicular information and programs are previously associated. The designated program is distributed to the gateway device along with an access right identifier defining an access right to the given ECU, and an electronic signature. When the gateway device determines that the received electronic signature is valid, the gateway device sets, to the received program, an access right to the ECU based on the distributed access right identifier.