Within vehicles, the Controller Area Network (CAN) allows efficient
communication between the electronic control units (ECUs) responsible for
controlling the various subsystems. The CAN protocol was not designed to
include much support for secure communication. The fact that so many critical
systems can be accessed through an insecure communication network presents a
major security concern. Adding security features to CAN is difficult due to the
limited resources available to the individual ECUs and the costs that would be
associated with adding the necessary hardware to support any additional
security operations without overly degrading the performance of standard
communication. Replacing the protocol is another option, but it is subject to
many of the same problems. The lack of security becomes even more concerning as
vehicles continue to adopt smart features. Smart vehicles have a multitude of
communication interfaces would an attacker could exploit to gain access to the
networks. In this work we propose a security framework that is based on
physically unclonable functions (PUFs) and lightweight cryptography (LWC). The
framework does not require any modification to the standard CAN protocol while
also minimizing the amount of additional message overhead required for its
operation. The improvements in our proposed framework results in major
reduction in the number of CAN frames that must be sent during operation. For a
system with 20 ECUs for example, our proposed framework only requires 6.5% of
the number of CAN frames that is required by the existing approach to
successfully authenticate every ECU.

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