An Efficient and Spontaneous Privacy-Preserving Protocol for Secure Vehicular Communications

1. An Efficient and SpontaneousPrivacy-Preserving Protocol for Secure Vehicular Communications Hu Xiong, Konstantin Beznosov, Zhiguang Qin, Matei Ripeanu presented by Jiaqi Gui Networked Systems Laboratory Electrical and Computer Engineering Department

2. Types of Applications Life-critical • alerting and monitoring functionality during intersection crossing, lane merging, etc. Value-added • enhancing drivers’ traveling experience by providing convenient Internet access, navigation, toll payment services, etc. NetSysLab@ubc.ece.ca 2

3. Types of Applications Life-critical • alerting and monitoring functionality during intersection crossing, lane merging, etc. • Security is critical! • Think of the damage a malicious attack could do Value-added • enhancing drivers’ traveling experience by providing convenient Internet access, navigation, toll payment services, etc. NetSysLab@ubc.ece.ca 3

4. Types of Applications Life-critical • alerting and monitoring functionality during intersection crossing, lane merging, etc. • Security is critical! • Think of the damage a malicious attack could do Value-added • enhancing drivers’ traveling experience by providing convenient Internet access, navigation, toll payment services, etc. NetSysLab@ubc.ece.ca 4

5. Structure of Proposed Infrastructure for Vehicular Networks Vehicular networks • Wireless communication devices installed on vehicles (On-Board Units - OBUs) • Road-side access points (RSUs) • Transportation Regulation Center (TRC) NetSysLab@ubc.ece.ca 5

6. Security Requirements for a Vehicular Communication Protocol • Conditional privacypreservation • Spontaneous • Efficient NetSysLab@ubc.ece.ca

7. Security Requirements … • Conditional privacypreservation • The identity of vehicles should be protected • However, incident investigation may require revealing identities of participating vehicles • Offline • Only by authorized parties • Spontaneous • Efficient NetSysLab@ubc.ece.ca

8. Security Requirements … • Conditional privacypreservation • Spontaneous • Protocol should not require communication between cooperating vehicles in the critical path before sending each new message • Protocol should not require support from the RSUs • RSUs may not cover all road segments at least in the initial deployment stages, • Efficient NetSysLab@ubc.ece.ca

9. Security Requirements … • Conditional privacypreservation • Spontaneous • Efficient • Low communication overheads • Low storage overhead • Should not rely on • a large storage space at each vehicle, or • updating the group public key and private key at all unrevoked vehicles in case of a growing revocation list • Low computational requirements NetSysLab@ubc.ece.ca

10. Existing/Proposed Solutions [LAB] M. Raya, J. P. Hubaux, Securing Vehicular Ad Hoc Networks, Journal of Computer Security, 15(1), 2007. [GSB] X. Lin et al., GSIS: A Secure and Privacy-Preserving Protocol for Vehicular Communications, IEEE Trans on Vehicular Technology, 56(6), 2007. [RSUB] R. Lu et al., ECPP: Efficient Conditional Privacy Preservation Protocol for Secure Vehicular Communications, INFOCOM 2008 (Note: only solutions that provide conditional privacy are presented) NetSysLab@ubc.ece.ca

11. Outline Introduction & Motivation Past Solutions The Proposed Solution Analysis Conclusions NetSysLab@ubc.ece.ca

12. Key Ingredients • Public/private keys. • Ring signature [Rivest et al. 2001] • Provides: • Anonymity: attacker can not infer which member of a group has signed. • Spontaneity: any member of a group can sign without additional setup • Revocable ring signature [Liu et al. 2007] • Provides conditional anonymity: an authority can reveal the identity of the real signer NetSysLab@ubc.ece.ca

13. Outline of the Proposed Solution Actual Message Signer Vehicle initialized with: • Its own public/private key pair: (xi,yi) • The public key of TRC: yTRC • Constants of the signature protocol NetSysLab@ubc.ece.ca

14. Outline of the Proposed Solution Vehicles encountered in the past yk – public keys … y1 yn y2 Actual Message Signer Vehicle initialized with: • Its own public/private key pair: (xi,yi) • The public key of TRC: yTRC • Constants of the signature protocol NetSysLab@ubc.ece.ca

15. Outline of the Proposed Solution Vehicles encountered in the past … y1 yn y2 Vehicle collects public keys of other vehicles encountered in the past Actual Message Signer Vehicle initialized with: • Its own public/private key pair: (xi,yi) • The public key of TRC: yTRC • Constants of the signature protocol NetSysLab@ubc.ece.ca

16. Outline of the Proposed Solution Vehicles encountered in the past … y1 yn y2 Vehicle generates the revocable ring signature using: • Its own private key: xi • A set of public keys of other N vehicles: y1,y2,…yn • The public key of TRC: yTRC • The message M Actual Message Signer Message Generation: (y1+y2+…+yn, M,yTRC ,xi) NetSysLab@ubc.ece.ca

17. Outline Introduction & Motivation Past Solutions Outline of the Proposed Solution Analysis Conclusions NetSysLab@ubc.ece.ca

18. Conditional Privacy Preservation Identity privacy preservation • Given a valid ring signature of a message, it is computationally difficult to identify the actual signer by any adversary • Property provided by ring signatures Tracing to a real identity • Given the signature, the TRC who knows xTRC, can reveal the real identity of a message sender NetSysLab@ubc.ece.ca

19. Spontaneous and Multi-Level Spontaneity • The vehicle can specify the ring (the set of vehicles) needed to generate the signature arbitrarily (i.e., without any new interaction with other vehicles or RSUs) [Additional property] Multi-level privacy • Each vehicle can select the degree of privacy that fits its own requirements by choosing the number of public keys used in the message generation phase. NetSysLab@ubc.ece.ca

20. Comparing Overheads to Existing/Proposed Solutions Hundreds or thousands of keys for each vehicle (all others schemes have one key pair per vehicle) [LAB] M. Raya, J. P. Hubaux, Securing Vehicular Ad Hoc Networks, Journal of Computer Security, 15(1), 2007. [GSB] X. Lin et al., GSIS: A Secure and Privacy-Preserving Protocol for Vehicular Communications, IEEE Trans on Vehicular Technology, 56(6), 2007. [RSUB] R. Lu et al., ECPP: Efficient Conditional Privacy Preservation Protocol for Secure Vehicular Communications, INFOCOM 2008 NetSysLab@ubc.ece.ca

21. Grows linearly with the number of revoked keys Comparing Overheads to Existing/Proposed Solutions [LAB] M. Raya, J. P. Hubaux, Securing Vehicular Ad Hoc Networks, Journal of Computer Security, 15(1), 2007. [GSB] X. Lin et al., GSIS: A Secure and Privacy-Preserving Protocol for Vehicular Communications, IEEE Trans on Vehicular Technology, 56(6), 2007. [RSUB] R. Lu et al., ECPP: Efficient Conditional Privacy Preservation Protocol for Secure Vehicular Communications, INFOCOM 2008 NetSysLab@ubc.ece.ca

22. Outline Introduction Motivation The proposed Scheme Analysis Conclusion NetSysLab@ubc.ece.ca

23. Conclusions The proposed protocol provides • conditional privacy, • improves efficiency in terms of the number of keys stored at each vehicle, and complexity of sender authentication and verification. • does not require support from the roadside infrastructure • provides multi-level privacy NetSysLab@ubc.ece.ca

24. Thank you For more information:http://NetSysLab.ECE.UBC.ca TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: A