Feature Article: Consumer Electronics Security Message Integrity and Authenticity in Secure CAN Timothy Dee and Akhilesh Tyagi Iowa State University Abstract-Existing vehicles and emerging smart vehicles organize their architecture around a controller area network (CAN) bus. Control messages with commands from one component cause another component to take an action. If a control message and action resulting from it is recorded by an adversary, it might be replayed for the same action. A connected smart vehicle is vulnerable to new attack vectors originating from other systems within a smart community. Existing CAN protocol does not prevent replay attacks. We develop a secure CAN protocol. A shared secret between nodes allows for confidential and authenticated messages. Use of a freshness value and keyed hash offer message integrity and staleness prevention. The distributed (centralized) bandwidth of 958.5 (934.3125) Kb/s compares favorably with the CAN protocol. Base CAN-FD protocol without any security achieves 9:8% higher bandwidth than the distributed secure CAN. & CONTROL AREA NETWORK (CAN) bus is common in vehicles. A smart vehicle in a connected smart city will dynamically add and delete many nodes from this bus as the moving vehicle's dynamic context evolves. This creates a new attack vector for these smart vehicles. Control messages are used to actuate an action. The integrity of these messages Digital Object Identifier 10.1109/MCE.2020.3035908 Date ofpublication 4 November 2020; date ofcurrent version 5August 2021. from a man-in-the-middle tampering attack should be maintained. The origin of a control message from an authentic source should be verified so that unauthorized parties do not control the vehicle. CAN bus operates with limited bandwidth. The previous CAN standards1 operate at a bus band width of 1Mb/s. Real time constraints to preserve the functional behavior are prioritized for bandwidth over security constraints. Historically, these vehicles were isolated nodes rendering the integrity and authenticity as unnecessary requirements. In a densely and September/October 2021 Published by the IEEE Consumer Technology Society 2162-2248 ß 2020 IEEE 33