Privacy conserving low volume information retrieval from backbone services in VANETs

Mobile ad hoc networks are of high interest in research and practice, especially as realizations in the automotive domain. Wireless data exchange, safety critical use cases and privacy requirements impose tough challenges on applied security mechanisms. Well studied solutions are available for direct communication between nodes. However, also time critical data retrieval from backbone services is required for many use cases, like the delivery of pseudonym certificates. This topic has not been looked at in detail in prior work. We show that the approach proposed in standards bears significant drawbacks. High effort in the input message validation process causes a denial of service weakness of backbone services. Moreover, request messages contain removable data sets making them unnecessarily long, which leads to high bandwidth requirements for reliable communication between backbone and mobile node. Thus, we propose a new data retrieval scheme increasing robustness of the backbone to denial of service attacks and decreasing length of nodes' request messages. The conducted evaluation shows good usability of the approach.