The present disclosure relates to a system for authenticating a computerized sub-system of a vehicle, comprising: (A) at the vehicle: (a) a tele-processor configured to periodically record during a period T1 a flow of messages over a bus of the vehicle's sub-system, and to transmit periodically every period T2 the recorded flow of messages to a remote server via a transceiver; (B) at a remote authentication server: (b) a transceiver configured to receive each of said recorded flow of messages; (c) a profile generator configured to generate from each of said flow of messages a temporary profile; and (d) a comparator configured to compare each of said temporary profiles with a final profile which was previously created based on one or more of flows of messages within the vehicle's bus.