Apparatus and method for transparent, secure element-based mediation of on-board diagnostic operations

An apparatus and method of an attachment device for interfacing with an on-board diagnostic system of a vehicle is provided. The device includes an application processor configured to receive input from a terminal, control processing of the input by the on-board diagnostic system, transmit a result of the processing of the input by the on-board diagnostic system to the terminal, and a secure element interposed in the communication path between the application processor and the on-board diagnostic system, the secure element configured to filter the input of an on-board diagnostic operation that is untrusted.