A Scalable and Secure Key Distribution Scheme for Group Signature based Authentication in VANET. Kiho Lim, Kastuv M. Tuladhar, Xiwei Wang, Weihua Liu

Transcription

1 A Scalable and Secure Key Distribution Scheme for Group Signature based Authentication in VANET Kiho Lim, Kastuv M. Tuladhar, Xiwei Wang, Weihua Liu

2 Outline Introduction to Vehicular Networks Motivation System Model Secure Key Distribution Scheme Evaluation & Analysis Conclusion

3 Introduction to Vehicular Networks Vehicular Ad hoc Networks (VANET) are a special type of Mobile Ad hoc Networks (MANETs) with fast-moving vehicular nodes, dynamically changing topology. VANETs allow vehicles to share safety and traffic information such as weather information, broadcasting emergency condition, navigations etc.

4 Vehicular Networking Source: Vehicular Networking: Standards, Protocols, Applications, and Deployment Plans, Tutorials, 2015 IEEE CCNC

5 Electronics in the vehicle Individual functions (like detecting seat occupancy) are performed by individual embedded systems, called Electronic Control Units (ECUs) essentially a ruggedized miniature computer, typically based on a microcontroller, that can gather data from attached sensors or trigger attached actuators

6 Extension to Vehicle-to-Vehicle Communications The next stage is to connect the in-vehicle network of a car with other cars, as well as with its environment, to open a whole set of new possibilities

7 Typical Connections Specifically designed protocols between Roadside Units (RSU) and vehicles; and vehicles to vehicles: IEEE WAVE, IEEE p, ITS-G5, ARIB T109

8 Vehicular Networking Objectives Safety-relevant information can be exchanged that can not be obtained using local sensors Enables the driver to see through and ahead other vehicles, buildings and environment Potential to improve driving comfort Potential to reduce congestion and thus environmental impact And, sometime in the future, enable fully automated rides

9 Cooperative Safety Systems Some Examples

10 Security Issues Propagation of falsified warning messages can mislead towards an accident and damage the life/property. Various Attacks in VANETs: bogus information attacks spoofing attacks (Identity, speed, position) privacy attacks

11 Real World Attack #1: RollJam Rolling Code for Keyless Entry unlock #n unlock #n+1 unlock #n+2 /17

12 Real World Attack #1: RollJam jam and capture #nnot opened! unlock #n jam and capture #n+1 unlock #n+1 replay #n opened! replay #n+1 opened! /17

13 Real World Attack #2: VW RKE Hack In USENIX Security 2016, Garcia et al. present that only 4 encryption keys are universally used over 100M vehicles produced by VW group over the 20 years. 1 /17

14 Real World Attack #3: FCA Jeep Hack After the first release in 7/21/2015, it drew significant media attention. FCA Jeep Cherokee remotely controlled by Charlie Miller and Chris Valasek. On 7/24/2015, FCA issued a recall to 1.4M vehicles. FCA SDN TCU Hackers IVI CAN bus PCM BCM FCA Jeep Cherokee /17

15 Real World Attack #4: Remote Tesla Model S Hack /17

16 Motivation It is difficult to store/manage all keys in a vehicle. Centralized trusted authority has high burden of generating and managing the group public/private keys. Another challenge in VANETs is delivering group private keys securely from the key generator to vehicular nodes. A group is confined to the coverage of a road side unit (RSU). Thus, our goal is to mitigate frequent key updates requirement and to make the key management process more efficient and scalable.

17 Related Works Chaum et al. [4] introduced group signatures for anonymous authentication, which employs several group keys corresponding to one group public key. Sun et al. [14] proposed a pseudonymous authentication for vehicular communication to provide anonymity and traceability. A distributed key management framework [5] distributes the group key with the help of RSUs. However, frequent key establishment has not been addressed. Also, delivering the group keys in a secure manner is crucial.

18 System Model Overview of the System Model

19 System Model Trusted Authority (TA): Vehicles are registered by the trusted authority and provided the certificates. TA and RSUs are securely connected by the stable backbone network. TA can help RSUs to identify the real identity of vehicles on request. Vehicular Nodes: Vehicular nodes are vehicles on the road which are equipped with an on-board unit (OBU) for computation and communication, a global positioning system (GPS) for location service, and an interface for interacting with drivers.

20 System Model Road Side Units (RSU) and Domain: RSUs are the infrastructure deployed along the road side which play an important role in key management, message authentication/verification, and message dissemination. A group of RSUs forms a domain. The number of RSUs within a domain can be determined based on the geographical status, infrastructure capacity, deployment plan and vehicle demography. RSUs are further classified into member RSUs (M-RSU) and leader RSUs (L-RSU).

21 System Model Leader Road Side Units (L-RSU): The L-RSUs coordinate with the trusted authority and generates the group private keys and group public keys for the vehicles. The L-RSUs also manage and maintain the database of the group keys. Upon detecting suspicious behavior, the L-RSUs communicate with the TA to reveal the identity of the malicious vehicle. Member Road Side Units (M-RSU): Unlike LRSUs, M-RSUs do not perform the key generation and management process, but instead M-RSUs can help vehicles to obtain the group keys from a leader RSU. Thereby, M-RSUs are semi-trust with the medium security level. Once the vehicle gets the group key, it can communicate with any M-RSU inside a domain with the same key.

22 Proposed Scheme The proposed protocol utilizes short group signature protocol[14] to generate a group private key. The leader RSU as a key generator issues group private keys within a domain. In a domain which consists of multiple RSUs, there are one group public key and many corresponding group private keys so any member of a domain can sign messages. A vehicle can use the same group key with multiple RSUs within a domain without having to initiate a key establishment process.

23 Proposed Scheme Figure illustrates how vehicles can request a group private key to the leader RSU within a domain.

24 Secure Key Distribution Scheme As a vehicle enters an area of a domain, it can communicate with any RSU to securely obtain group public/private key pair. The secure key distribution scheme is based on the Diffie- Hellman key agreement protocol for mutual authentication and sharing a symmetric key. Vehicles and M-RSU shares the related parameters to get the symmetric key. g ab serves as the secret key K Vi_MR between Vi and M-RSU

25 Secure Key Distribution Scheme After establishing a symmetric key, vehicle requests for the group keys to M-RSU. M-RSU forwards the request to the L-RSU. L-RSU replies to M-RSU with the group keys for the vehicle. Finally, M-RSU transmits the group keys to vehicle using the shared symmetric keys.

26 Secure Key Distribution Scheme Domain M-RSU m4 m5 L-RSU m1 m3 m6 m2 Our Protocol Flow M-RSU Regular Communication

27 Secure Key Distribution Scheme

28 Evaluation & Analysis Simulation Setup Manhattan Grid environment simulated in the Network Simulator NS-2 and the mobility simulator SUMO. Map of 3600*3600 square meters.

29 Key Establishment

30 Key Establishment When the domain of multiple RSUs is not considered, vehicles have to perform the key exchange procedure with each and every RSUs separately. The figure shows how the average number of key establishment changes as the vehicles are moving with/without using domains. Here, domain has the area covered by four RSUs with the vehicles moving randomly.

31 Key Establishment Delay Comparison [14]

32 Key Establishment Comparison The computation time of the group signature [14] measured that the signing and the verification delays are 3.6 ms and 7.2 ms for key transaction. The signing and verification process of the 16 key establishments without using domain takes 16*( ) ms (172.8 ms). On the other hand, while using the domain size of four RSUs, the time taken for signing and verification of four key establishments is 4*( ) ms (43.2 ms).

33 Key Establishment Comparison Thus, with the domain size of only four RSUs, the timetaken for key establishment of the randomly moving vehicles is 43.2 ms which is 400% more efficient compared to the ms (time taken for key establishment without domain). In practice, the domain size is likely to be higher, so it can be expected that our scheme will achieve more efficiency.

34 Group Key Utilization Group key utilization time is the time that the vehicle travels inside the domain after establishing the key. Group key utilization time can be used to consider the frequency of the group key usage in domains and get idea about average travel time of the vehicles in various. The Figure shows the group key utilization time for different size of vehicles after receiving the group keys under the different size of domain.

35 Group Key Utilization

36 Group Key Utilization It is observed that the vehicles spends around seconds in one RSU on average. And the average travel time is continuously increasing as the size of the domain increases. When there are four RSUs within a domain, it is observed that the moving vehicles utilize the group key about 200% more than the moving vehicles without having a group key for the domain.

37 Conclusion Our scheme provides the scalable solution for the security of the vehicular networking by using the concept of domain with multiple RSUs so that a group key can be utilized for a longer period of time. In addition, by splitting the role of the RSU to member RSU and leader RSU, our approach provides the distributed key management mechanism. Furthermore, our scheme offers the secure key exchange protocol which allows that group keys can be securely delivered to vehicular nodes.

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