In-vehicle device, management device, transmission path authentication system, transmission path authentication method, and management method

This vehicle-mounted device is mounted on a vehicle, and is provided with: a storage unit that stores characteristic data indicating characteristics of a transmission path in a vehicle-mounted network mounted on the vehicle; a measurement unit that measures characteristics of the transmission path; and an authentication unit that performs authentication processing of the transmission path using a result of comparison between the characteristic data in the storage unit and a measurement result by the measurement unit. 车载装置，是搭载于车辆的车载装置，具备：存储部，存储表示搭载于所述车辆的车载网络中的传输路径的特性的特性数据；测定部，测定所述传输路径的特性；以及认证部，使用所述存储部中的所述特性数据与所述测定部的测定结果的比较结果，进行所述传输路径的认证处理。