Sender Authentication for Automotive In-Vehicle Networks through Dual Analog Measurements to Determine the Location of the Transmitter

Controller Area Network (CAN) is a fundamentally insecure communications bus. Its intrinsic lack of sender
authentication makes impersonation attacks a severe threat to the security of systems that rely on CAN for
communication between devices. In this paper, we propose a novel technique to enforce sender authenticity
on a CAN bus. The technique is reliable, robust, and reasonably easy and inexpensive to implement, as it relies
on non-clonable physical characteristics of the transmitted signals. In particular, we measure the analog signal
at two different locations on the CAN bus physical wire; the signal corresponding to the transmitted message
travels through the wire at a certain speed, which allows us to determine the physical location (i.e., position
along the wire) of the transmitter as a function of the relative delay between the two analog measurements.
Our work includes an experimental evaluation on an actual vehicle, with results that suggest that the technique
is effective and practical.