Cryptology ePrint Archive: Report 2018/1106

P4TC---Provably-Secure yet Practical Privacy-Preserving Toll Collection

Max Hoffmann and Valerie Fetzer and Matthias Nagel and Andy Rupp and Rebecca Schwerdt

Abstract: Electronic toll collection (ETC) is widely used all over the world not only to finance our road infrastructures, but also to realize advanced features like congestion management and pollution reduction by means of dynamic pricing. Unfortunately, existing systems rely on user identification and allow tracing a user's movements. Several abuses of this personalized location data have already become public. In view of the planned European-wide interoperable tolling system EETS and the new EU General Data Protection Regulation, location privacy becomes of particular importance.

In this paper, we propose a flexible cryptographic model and protocol framework designed for privacy-preserving toll collection in the most dominant setting, i.e., Dedicated Short Range Communication (DSRC) ETC. As opposed to our work, most related cryptographic proposals target a less popular type of toll collection based on Global Navigation Satellite Systems (GNSS), and do not come with a thorough security model and proof. In fact, to the best of our knowledge, our system is the first in the DSRC setting with a (rigorous) security model and proof. A major challenge in designing the framework at hand was to combine provable security and practicality, where the latter includes practical performance figures and a suitable treatment of real-world issues, like broken on-board units etc.

For our ETC system, we make use of and significantly extend a payment protocol building block, called Black-Box Accumulators, introduced at ACM CCS 2017. Additionally, we provide a prototypical implementation of our system on realistic hardware. This implementation already features fairly practical performance figures, even though there is still room for optimizations. An interaction between an on-board unit and a road-side unit is estimated to take less than a second allowing for toll collection at full speed assuming one road-side unit per lane.

Category / Keywords: Toll Collection, Location Privacy, Provable Security, Universal Composability

Date: received 14 Nov 2018

Contact author: andy rupp at rub de

Available format(s): PDF | BibTeX Citation

Version: 20181116:133219 (All versions of this report)

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