Description: Field of Invention
Vehicular ad hoc networks (VANETs) facilitate vehicles to communicate each other in also with the support of infrastructure. The major parts of vehicular ad hoc networks are vehicles (entity or node), wayside access boxes (WAB), location servers and certification authorities (CAs). The dynamic nature of VANET makes it more vulnerable to attacks and has several security issues. A privacy location of a vehicular user is much important as the data sent by a vehicle may have important consequences like accident prevention.
Background of the Invention
The VANET users are greatly affected by threats over location privacy as they are not guaranteed privacy and the location of vehicle can be traced out using their broadcast. To overcome this drawback (Krishna Sampigethaya, et al. CARAVAN international conference on wireless and mobile computing, pages 508- 513, 2008) proposes an approach called CARAVAN. On considering the greater mobility, an approach was based on combining all neighboring vehicles and formed into a group. This group formation significantly mitigates the number of broadcast times that a vehicle uses for vehicle- to- infrastructure applications. This grouping mechanism helps in achieving extended silent period for each vehicle and thus anonymity gets improved. Additionally, an enhancement technique also suggested that considers the separation of RSUs and ability of a vehicle to control its transmission power. Threats may arise for VANET users from the LBS application used by it and it is effective in the global adversary model and over the safety application constraints. Provides anonymity in which the vehicle updates its keys on direction changes but using this system anonymity cannot be achieved in global adversary model.
The basic requirements regarding security and privacy between various communication devices in VANET are discussed in (Kewei Sha et al. Adaptive Privacy-Preserving Authentication in Vehicular Networks pages 1- 8, 2006). To meet these requirements, a secure and privacy defending protocol has been designed based on the Group Signature and Identity based Signature (GSIS) mechanism. GSIS approach does not offer only the security and privacy requirements but also offers traceability of every vehicle’s ID as it can be verified by certain authorities at dispute moment. Security issues are handled in two different aspects such as interaction between on- board units (OBUs) and interaction between OBU and road side unit (RSU). Group signature concept and ID based signature (cryptography) concept is used in the first and the second aspect respectively. The detailed description about privacy issues are addressed in (Jinyuan Sun et al., IEEE transactions on parallel and distributed systems, volume 21, issue 9, 2010). This deals with privacy and security of vehicle- to- infrastructure interaction for providing safety especially between vehicles and traffic light that act as a road side unit. This system mainly aims at managing privacy rather than providing a complete anonymity or no privacy at all.

Vehicular ad hoc networks (VANETs) facilitate vehicles to communicate each other in also with the support of infrastructure. The span of VANET is too short as the network topology is dynamic in nature. The nodes in the VANET moves in and out of the network frequently as it has greater dynamic mobility pattern. Moreover, the density of the network keeps on varying with respect to the traffic condition. The major parts of vehicular ad hoc networks are vehicles (entity or node), wayside access boxes (WAB), location servers and certification authorities (EP2789118B1). The dynamic nature of VANET makes it more vulnerable to attacks and has several security issues. A privacy location of a vehicular user is much important as the data sent by a vehicle may have important consequences like accident prevention. By using advanced techniques in localization and tracking one can find the exact location of a vehicle. By doing so, it is possible to gain information about the past history of vehicle it has visited. These informations can be further used in an illegal manner by a stranger. Moreover, private information or details of a user can be gathered by identifying the LBS services used by a vehicle.
There are two approaches in VANET. One is vehicle- to- vehicle interaction and the other is vehicle- to- infrastructure interaction(US20150365876A1). In vehicle- to- vehicle interaction, there is no need for fixed infrastructure or any wayside access boxes and it is purely ad hoc in nature. In this a vehicle interacts only with other vehicle to estimate the traffic condition. On the other hand, in the case of vehicle- to- infrastructure interactions, interactions are held between a vehicle and a fixed infrastructure like wayside access boxes. This kind of infrastructure provides aggregation, key distribution to the vehicles. The major issue to be considered in this architecture is number of required wayside access boxes cannot be predicted. VANET has several security issues such as location privacy, traceability, availability, integrity, confidentiality, and authentication, non repudiation, and non frameability, miscellaneous. An efficiency of any system that provides a solution to above problems can be estimated using storage, efficiency in communication and computational efficiency(Azzedine Boukerche, et. al.,www.elsevier.com/locate/com).
Privacy is associated with the authentication in which a node or user must be binded to a single unique identity. The VANET users achieves only 50- 60% of availability of the network and it is based on the dedicated short range communication (DSRC) value. In the case of collision avoidance and warning systems, it can tolerate error only to some extent. Each VANET node has greater mobility and so they have constantly varying set of neighboring nodes(WO2010020260A1). It is much difficult to distribute keys in VANET as it arises many queries like when and where to distribute the key, number of keys to be installed and the name of the certification authority is not known. The forms of adversaries who attack the system model are greedy drivers, insider attackers, pranksters, malicious attackers and snoops. Though there are many issues in VANET, our project is concerned only with the location privacy and traceability.
Summary of the Invention
The idea behind this grouping is to find out the attacker in an easier way using the group identifier. The WABs are distributed with public key whereas the vehicles are distributed with private keys. Obviously, the trusted certificate authorities’ use only shared keys and all these keys are generated using key generator. The major issue in the certificate system is increase in the communication and computation overhead. In order to reduce the overhead, a certificate may be authorized partially. Location privacy is the central requirement in the VANET.

Brief Description of Drawings
The invention will be described in detail with reference to the exemplary embodiments shown in the figures wherein:
Figure 1: VANET hierarchy
Detailed Description of the Invention
Our proposal suggests that good authentication system can provide good privacy preservation. The proposed authentication system involves 4 steps. In the first step, the vehicle sends the request to WAB for authentication of vehicle. In the second step, the WAB forwards the request to TCA. The TCA sends the trusted certificates to the WABs group in the third step. At the final step, the WAB responds to the vehicle.
Vehicle (VH) communicates with WABn (VH/ WABn), In the first step, the vehicle sends request to the WAB for authentication. A vehicle’s request must contain the following information. Message type indicates the type of the message and it is 1 byte field. The field payload indicates the position, direction, acceleration of the vehicle and it is generally 100 byte field. The TTL field indicates the time period or validity of the message that is allowed to remain in the VANET or in the transmission range of WAB group. WAB group ID is used to identify the group of the vehicle which it belongs to. Temporary ID of the vehicle represents the pseudo ID in order to conceal its original ID. SignVH field indicates the vehicle’s signature on the previous six fields. The vehicle sends the authentication request to nth WABn. The private key of the vehicle encrypts the timestamp and vehicle identity.
WABn communicates with TCA (WABn/ TCA), in this step, WABn forwards the vehicle’s request to the TCA. The WABn decrypts the timestamp value and vehicle’s temporary identity from the vehicle and store it for a session until the TCA does not responds to the WAB request. After the decryption, the WABn forwards the encrypted packet (excluding the decrypted timestamp value and vehicle’s temporary ID) to the TCA, The TCA then decrypts the WABn authentication request using its public key and verifies the vehicle and WABn.
TCA communicates with WABn (TCA/ WABn), As soon as the completion of the authentication process of vehicle and WABn, TCA will issue trusted certificate (trusted_cert) with TTL to the vehicle through WABn. The trusted certificate is valid until the TTL value gets expired. The validity of the trusted certificate also depends on the duration of stay of the vehicle in a WAB moving at average high speed. Therefore, different vehicles will have trusted certificates with different TTL value. Simultaneously, TCA will inform to all other WABs in that particular group about the authentication of the vehicle. Finally, all the WABs in a group have knowledge about the authentication of the particular vehicle. The WABn has to verify whether the encrypted packet is equal to CTA temp_IDVH and TTL. If both the values are same then the vehicle can authenticate WAB. WAB communicates with VH (WAB/ VH), This is the final step in the authentication process in which the WAB responds to the vehicle’s request. The WABn forwards the trusted certificates to the vehicle and at the same time the vehicle authenticate the WAB group. These are the steps to be followed at the time of authentication of vehicle. Whenever a vehicle enters the other group of WAB it has to re authenticate. In addition, in the case of expiry of trusted certificate, the vehicle must re authenticate using the 4 steps.
The privacy issue in VANET must be focused as it has greater significance in real time scenarios. The applications of VANET falls under three groups: warning messages, longitudinal control and road assistance. Warning messages include information about traffic over a certain area, and it also provides information about weather report. Longitudinal control includes collision avoidance, it greatly helps in avoiding accidents using look through obstacles and platooning. Road assistance model includes messages about intersection of roads and highway entry. Moreover, VANET is considered to be a vital component in Intelligent Transportation Systems (ITS), and plays an important role in several applications such as safety, driver assistance, and infotainment.
In safety ensuring applications, each vehicle is supposed to broadcast an authenticated safety message periodically enclosed with its verifiable identity, current location, acceleration, and speed. Though these safety messages assist in preventing the accidents, they are vulnerable to unauthorized adversaries who can track and access the location of the vehicle. With the help of WiFi network, an adversary can eavesdrop on all the messages broadcasted by the vehicles and predict the locations visited by the vehicles for a given time. The adversaries exploit the history of location information for several purposes including advertisement and surveillance. Therefore, strengthening the location privacy of vehicles is more significant as the failure of privacy may thwart the development of the VANET communication technology.
Though some approaches ensures privacy in VANET, there are still numerous unaddressed challenges yet to be analyzed. The common solution for privacy in VANET exploits pseudonyms and group formation. In the pseudonym based schemes, none of the works have discussed about the management of a massive short-tempseudonyms. In the group formation based schemes, it is a great challenge to maintain the constantly increasing number of revoked vehicles.
The VANET structure considered in our proposed system is shown in figure 1. A key generator distributes key to WABs and WABs distributes them to the vehicles under its transmission range. A vehicle makes a request for trusted certificate to WAB and then WAB forwards the request to TCA. TCA responds to the WAB’s request by distributing the keys and trusted certificate which in turn distributes it to the vehicle to carry out the vehicle to vehicle communication. More than 3 WABs can be combined to form a group so that vehicles under that group may have the common IDs which are identified by first two prefixes. It ensures one- to- one authentication i.e. vehicle authenticates WAB and in turn WAB authenticates a vehicle.
4 Claims & 1 Figure , Claims: The scope of the invention is defined by the following claims:

Claim:
1. The Ensuring Location Privacy in Vehicular Adhoc Networks writing comprising the following steps
a) The privacy of the vehicle is assured as they do not reveal their original identities at the time of communication with other vehicle or infrastructure.
b) Vehicles communicate with TCA only through WABs in a well secured manner. Therefore, issues regarding availability of trusted certification do not have great impact on the privacy factor.
c) A vehicle can request for authentication to WAB in the other group that is under the control of different TCA and the identities of malicious vehicle can be revealed in the case of detection.
2. The Ensuring Location Privacy in Vehicular Adhoc Networks as claimed in claim1, the privacy of the vehicle is assured as they do not reveal their original identities at the time of communication with other vehicle or infrastructure. No WAB stores the details of original vehicle ID to temporary vehicle ID. So, a WAB has the knowledge about the vehicles with which it communicates.
3. The Ensuring Location Privacy in Vehicular Adhoc Networks as claimed in claim1, Vehicles communicate with TCA only through WABs in a well secured manner. Therefore, issues regarding availability of trusted certification do not have great impact on the privacy factor.
4. The Ensuring Location Privacy in Vehicular Adhoc Networks as claimed in claim1, A vehicle can request for authentication to WAB in the other group that is under the control of different TCA and The identities of malicious vehicle can be revealed in the case of detection.