  Vehicle technology has developed rapidly these years, however, the security
measures for in-vehicle network does not keep up with the trend. Controller
area network(CAN) is the most used protocol in the in-vehicle network. With the
characteristic of CAN, there exists many vulnerabilities including lacks of
integrity and confidentiality, and hence CAN is vulnerable to various attacks
such as impersonation attack, replay attack, etc. In order to implement the
authentication and encryption, secret key derivation is necessary. In this
work, we proposed an efficient key management scheme for in-vehicle network. In
particular, the scheme has five phases. In the first and second phase, we
utilize elliptic curve cryptography-based key encapsulation mechanism(KEM) to
derive a pairwise secret between each ECU and a central secure ECU in the same
group. Then in the third phase, we design secure communication to derive group
shared secret among all ECU in a group. In the last two phases, SECU is not
needed, regular ECU can derive session key on their own. We presented a
possible attack analysis(chosen-ciphertext attack as the main threat) and a
security property analysis for our scheme. Our scheme is evaluated based on a
hardware-based experiment of three different microcontrollers and a
software-based simulation of IVNS. We argue that based on our estimation and
the experiment result, our scheme performs better in communication and
computation overhead than similar works.
