FLIP: An Efficient Privacy-preserving Protocol for Finding Like-minded Vehicles on the Road

1. FLIP: An Efficient Privacy-preserving Protocol for Finding Like-minded Vehicles on the Road Rongxing Lu, Xiaodong Lin, Xiaohui Liang, Xuemin (Sherman) Shen University of Waterloo, University of Ontario Institute of Technology Presenter: Rongxing Lu Email: rxlu@bbcr.uwaterloo.ca

2. Outline • Introduction • VANET, Vehicle Chatting Application • System & Security Model • Proposed FLIP Protocol • Security Proof • Performance Evaluation • Conclusion

3. Introduction: VANET VANET V-2-I V-2-V Vehicle equipped with OnBoard Unit (OBU) Road Side Unit (RSU) Server (traffic monitoring, location based service) Vehicular Ad hoc Networks (VANETs), as a special instantiate of mobile ad hoc network, have been subject to extensive research efforts not only from the government, but also from the academia and automobile industry in recent years.

4. Introduction: VANET Application V-2-V V-2-V Warning Sharing MP3 Accident Chatting Server (traffic monitoring) Server V-2-I V-2-I Downloading MP3, Map, Software Booking hotel road info. Safety-Related Application Nonsafety-Related Application

5. Introduction: Vehicle Chatting Future Carpool New Movie Music Chatting Vehicle chatting is one of the most promising applications in VANETs, which allows vehicles moving along the same road to chat with each other on some topics of common interest, for the purpose of passing the time during the commute or asking for a help on the road. However, the success of vehicle chatting application in VANET still hinges up the fully understanding and managing the security and privacy challenges that the public concerns, for example, the identity privacy, location privacy, and interest privacy.

6. Introduction: Contribution How to identify a vehicle who is like-minded and establish a shared session key for secure chatting, and how to prevent other vehicles who are not like-minded from knowing one vehicle’s interest have become two newly emerging privacy challenges in vehicle chatting application. Contribution: we propose an efficient privacy-preserving finding like-minded vehicle protocol, called FLIP, which allows two vehicles with the common interest to identify each other and establish a shared session key, and at the same time, protects their Interest-Privacy (IP) from other vehicles who don’t have the same interest on the road.

7. System Model FLIP: try to find a physically nearby like-minded vehicle without directly disclosing own interest; and establish a secure key to protect the future chatting content Trusted Authority: Assign a family of pseudo-IDs to vehicle Each Vehicle: Periodically change pseudo-IDs

8. Security Model Rationale: For a given interest set of k items, if Vb really has the same interest with Va, with high probability, both Va and Vb can choose the same interest. Otherwise, Vb can choose the same interest of Va only with probability 1/k. FLIP Preconditions: 1)The size of the Interest Set I should be large. 2) In each execution of FLIP, the Interest Iavaries (pseudo-id fixed)

9. Security Model (2) Adversarial Model We allow the adversary A to access to all transcripts in the FLIP. All oracles only communicate with each other via A. The adversary A can replay, modify, delay, interleave or delete transcripts. FLIP Passive Eavesdropping

10. Security Model (3) Adversarial Model FLIP Use the query to perform active attacks by modifying and inserting the transcript of the protocol to identify the IP of the requestor and responsor

11. Security Model (4) Adversarial Model FLIP This query models the known session key attack. The adversary A can get access to an old session key that has been previously established. This query models exposure of the private key corresponding to PIDi to the adversary

12. Proposed FLIP Protocol

13. Security Proof Full version: http://bbcr.uwaterloo.ca/~rxlu/paper/GLOBECOM10FLIP.pdf

14. Performance Evaluation 40 km/h - 80 km/h, 300 m Interest set size [1; 2; . . . ; 10] Finding Delay Mean passing-by rate =[20 /h; 40 /h; 60 /h; 80 /h; 100 /h; 120 /h] The larger the Interest Set, the longer the average FD; but at the same time, the average FD can be reduced with the increase of λ. Therefore, by setting a proper size of |I| on considering of λ, a vehicle V can find a like-minded vehicle within an expected time on the road while keeping his IP from non-like-minded vehicles.

15. Conclusion In this work, we propose a secure finding like-minded vehicles protocol (FLIP), which can protect vehicle’s IP and is of vital importance to the success of vehicle chatting application on the road How to find a group of like-minded vehicles on the road is one of future work. Thank you!