Pseudonym Certificate Validations under Heavy Vehicular Traffic Loads

The Security Credential Management System (SCMS) has been proposed to provide a trust framework that ensures integrity, authenticity, and unlinkability of DSRC messages by issuing pseudonyms with implicit certificates. Nevertheless, validating the integrity and authenticity of a message at an On-Board Unit (OBU) incurs processing delays of about 22ms. Given that Basic Safety Messages (BSMs) are emitted by every vehicle at a rate of 10Hz creates many messages to be validated by an ego vehicle under heavy vehicular traffic. Such traffic loads may create delays in the processing of safety critical messages. In order to avoid such delays, we propose a message processing algorithm that provides a 3 level processing priority based on the immediate neighborhood of an ego vehicle. We show that our algorithm performs well under increasing vehicular traffic loads on realistic highway scenarios measured with respect to message deadline miss ratios and accumulating unprocessed message queue lengths. Further, we propose extending SCMS with cross certification capabilities in order to facilitate seamless certificate validation across administrative boundaries with individualized SCMS trust roots.