Faster verification of V2X basic safety messages via Message Chaining

Abstract

Vehicular-to-Everything (V2X) communications enable vehicles to exchange messages with other entities, including nearby vehicles and pedestrians. V2X is, thus, essential for establishing an Intelligent Transportation System (ITS), where vehicles use information from their surroundings to reduce traffic congestion and improve safety. To avoid abuse, V2X messages should be digitally signed using valid digital certificates. Messages sent by unauthorized entities can then be discarded, while misbehavior can lead to the revocation of the corresponding certificates. One challenge in this scenario is that messages must be verified shortly after arrival (e.g., within centiseconds), whereas vehicles may receive thousands of them per second. To handle this issue, some solutions propose prioritization or delayed-verification mechanisms, while others involve signature schemes that support batch verification. In this manuscript, we discuss two mechanisms, one based on Message Authentication Codes, and one based on hash chaining, that complement such proposals, enabling the authentication of a sequence of messages from the same source with one single signature verification. Our analysis shows that the technique can reduce the number of verified signatures and computational costs by around 90% for reliable communication channels, and by more than 65% for a maximum packet loss rate of 20%.