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

An Efficient and SpontaneousPrivacy-Preserving Protocol for Secure Vehicular CommunicationsHu Xiong, Konstantin Beznosov, Zhiguang Qin, Matei Ripeanu

presented by Jiaqi Gui

Networked Systems LaboratoryElectrical and ComputerEngineering Department

An Efficient and Spontaneous Privacy-Preserving Protocol [email protected] 2

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.

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Types of Applications



intersection crossing, lane merging, etc. Security is critical!

Think of the damage a malicious attack could do



3




intersection crossing, lane merging, etc. Security is critical!

Think of the damage a malicious attack could do



4



Wireless communication devices installed on vehicles (On-Board Units - OBUs)

Road-side access points (RSUs)

Transportation Regulation Center (TRC)

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Structure of Proposed Infrastructure for Vehicular Networks

Vehicular networks

IEEE 802.11pCommunication Technology

Transportation Regulation Center


Conditional privacy preservation Spontaneous Efficient

Security Requirements for a Vehicular Communication Protocol


Conditional privacy preservation The identity of vehicles should be protected However, incident investigation may require revealing

identities of participating vehicles Offline Only by authorized parties

Spontaneous Efficient

Security Requirements …


Conditional privacy preservation 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



Conditional privacy preservation 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



Existing/Proposed Solutions

Spontaeous Efficiency Storage Overhead Verification Overh.

Solutions using a large numbers of anonymous keys (LAB)

Yes High Low

Solutions based on pure group signature (GSB)

Yes Low High

Solutions based on using the roadside infrastructure (RSUB)

No (RSU aided)

Low Low

Proposed solution (based on revocable ring signature)

Yes Low Low

[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)


Introduction & Motivation Past Solutions The Proposed Solution Analysis Conclusions

Outline


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


Outline of the Proposed Solution

Actual MessageSigner

Vehicle initialized with:

• Its own public/private key pair: (xi,y

i)

• The public key of TRC: yTRC

• Constants of the signature protocol



y1 y2yn…


Vehicles encountered in the past y

k – public keys



i)





y1 y2yn…


Vehicles encountered in the past



i)



Vehicle collects public keys of other vehicles encountered in the past



y1 y2yn…


Message Generation: (y1+y2+…+yn, M,yTRC ,xi)

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 message M

Vehicles encountered in the past


Introduction & Motivation Past Solutions Outline of the Proposed Solution Analysis Conclusions

Outline


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

Conditional Privacy Preservation


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.

Spontaneous and Multi-Level


Comparing Overheads to Existing/Proposed Solutions



Yes High Low


Yes Low High

Solutions based on using the roadside infrastructure (RRUB)

No (RSU aided)

Low Low

Proposed solution (RSUB)(based on revocable ring signature)

Yes Low Low



Hundreds or thousands of keys for each vehicle

(all others schemes have one key pair

per vehicle)


Comparing Overheads to Existing/Proposed Solutions



Yes High Low


Yes Low High

Solutions based on using the roadside infrastructure (RRUB)

No (RSU aided)

Low Low

Proposed solution (RSUB)(based on revocable ring signature)

Yes Low Low



Grows linearly with the number of revoked keys


Introduction Motivation The proposed Scheme Analysis Conclusion

Outline


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

Conclusions

For more information:http://NetSysLab.ECE.UBC.ca

Thank you

Documents

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