Eriko Ando

A Proposal of Security Requirements Definition Methodology in Connected Car Systems by CVSS V3

The use of connected cars has been spreading recently. Security for connected cars is very important because an attacker can access connected cars remotely. Security requirements defined based on risk assessment are necessary to protect connected cars from attackers. However, the conventional risk assessment technique mostly depends on the evaluators security knowledge. Therefore, we propose a security requirement definition methodology for connected car systems. The proposed methodology is based on the security requirements definition methodology in IoT (Internet of Things) systems, which consists of four processes: modelization of target system, definition of security problems, consideration of security requirements, and decision of security function components. We applied the methodology in IoT systems to connected car systems. In particular, the risk assessment, which is executed to define security problems, uses CVSS v3 which was released in 2015. We can assess the risk of connected car systems objectively by using the base metrics of CVSS v3.

Symmetric key distribution for car-to-car/infrastructure communication systems

Services such as sending a pre-crash sensing warning and traffic condition warning are expected to be provided in car-to-car/infrastructure (C2X) communication systems. Maintaining message integrity is essential for these services because wrong messages may cause collision accidents and congestion. A message authentication code (MAC) generated by using a symmetric key is used to authenticate a message. The sender and receiver of a message must possess the same symmetric key before initiating communications. In the mentioned warning services, the sender of a message cannot know who receives the message, because the message is broadcast. Moreover, it is difficult for a road-side unit (RSU) to distribute a key to an onboard unit (OBU) because an OBU cannot always communicate with a RSU. Therefore, key distribution is a problem in C2X communication systems. We thus propose a protocol for key distribution. In the protocol, all OBUs and RSUs that exist in a certain area possess the same key. An OBU obtains the keys for the area in which the OBU is present and for the area to which the OBU will go next. The protocol enables a vehicle to verify message integrity by using a symmetric key in C2X communication systems.