International Journal of Application or Innovation in Engineering & Management (IJAIEM) Web Site: www.ijaiem.org Email: editor@ijaiem.org Volume 4, Issue 7, July 2015 ISSN 2319 - 4847 TRUST COMPUTATION TECHNIQUES IN VANETS DEEPIKA SARASWAT1, CHANDRA PRAKASH BHARGAVA2 1 DEEPIKA SARASWAT, ITM GOI, GWALIOR 2 CHANDRA PRAKASH BHARGAVA , ITM GOI,GWALIOR ABSTRACT In this work, we present a analytical hierarchy process (AHP) for computing trust in the vehicular ad hoc networks (VANETs). AHP based trust management provides a lightweight security alternative to existing security techniques. Trust Management in VANETs is required to broadcast of selfish or malicious messages and also enable other vehicles to filter out such messages. A trust management system has ability to cope with sparsity of direct interactions. To evaluate the trust, we introduce the AHP based technique constitutes the combination of direct, reputation and indirect trust technique. The AHP is also used to coalesce various recommendation opinions from neighbour vehicles through exchanges of messages. Result shows that the scheme is lightweight and completes in order of milliseconds. Keywords- Trust management; VANET; AHP; ranking; 1. INTRODUCTION VANETs are a network of vehicles moving on the road. It is supposed to provide vehicles with reliable and efficient data transmissions for various applications, especially for the broadcast-based safety message [1]. Dedicated short range communication (DSRC) radio technology, being standardized as IEEE 802.11p [2], is recommended to support lowlatency wireless data communications between vehicles and from vehicles to road side infrastructure . The DSRC recommends a transmission range between 250-300 m and 1000 m for vehicles and respectively, signal bandwidth of 10 MHz and data rate from 3-27 Mbps. In VANETs, vehicles exchange critical information; a malicious vehicle may inject false messages with different identities. Authenticated vehicles may also play a role of malicious vehicle or broadcast false messages. So, there is an urgent need of effective trust management for VANETs, given the dire consequences of acting on false information sent out by the malicious vehicles. The trust management system should be quickly compute the trust, simple (not complex), accurate, scalable and resilient to threats. VANETs have some unique characteristics which differentiate them from other ad hoc networks such as high mobility, decentralized system, predictable topology and high density network. Based on the unique challenges in VANETs, some desired prosperities for trust management in VANETs are decentralized trust establishment, coping with data sparsity, event and location time specific, robustness, scalable, integrated confidence measure, system level security, and sensitive to privacy concerns [3]. In general, trust is based on the analysis of several messages reporting on the same event [4] or trust is a process by which relationships develop [5]. Existing literature having very few trust models in VANETs. In [6], trust models are categorized into three types, entity-oriented, data-oriented and combined trust model. Group formation of trusted vehicles based approach is presented in [7]. Some other trust management frameworks are as follows. Trust based security system, TOMS (trust computation and management system), used to establish a set of effective rules to make reliable analysis of certain suspicious nodes [8]. It assigns credentials to nodes, updating private keys, managing the trust value of each node, and making appropriate decisions about nodes’ access rights. In [9], trust including situational trust depends on situation only and dispositional trust based on a peer’s own beliefs. However, formalization of the architecture about how to combine the different types of trust together is an issue of this scheme. In [10], multi faced trust management model is discussed. The sociological trust model is proposed based on the principle of trust and confidence tagging. We have proposed AHP based trust computation technique in VANETs. The remainder of the paper is structured as follows. Section II contains a problem definition. In Section III we present the proposed AHP based trust computation approach in VANETs. Section IV simulation and results is presented. In Section V concludes the work. 2. PROBLEM DEFINITION The trust establishment process in VANETs must take into consideration the direct messages, forwarded messages from vehicles, aggregated recommendation of other vehicles about a vehicle and messages and the nature of messages. In VANETs, authenticated or good vehicle may play the role of malicious vehicle or may broadcast wrong messages. This requires a method that can take all the parameters into consideration. It is very necessary to take recommending vehicles' opinion into account. In addition, adopting recommending vehicles' opinion, evaluated vehicle should take account of its role. To address this need, trust computation of vehicles in VANETs is required. Volume 4, Issue 7, July 2015 Page 197 International Journal of Application or Innovation in Engineering & Management (IJAIEM) Web Site: www.ijaiem.org Email: editor@ijaiem.org Volume 4, Issue 7, July 2015 ISSN 2319 - 4847 3. PROPOSED METHOD Analytical hierarchy process (AHP) is a multicriteria decision technique that uses hierarchical approach to evaluate the trust value of vehicles to prevent false dire consequences messages in VANETs. The proposed AHP based technique has three steps. Reputation Based trust computation is the first step. Direct ranking trust computation is second step and in the third step is based upon indirect ranking. All three steps constitute a trust value of vehicle using AHP method. Reputation based trust computation: In this step, trust value depends upon previous records of vehicle. If vehicle is not listed in revocation value then trust value is 1 otherwise 0. Reputation based trust value is denoted by Trep . If some vehicles are police cars and traffic controllers, school vans, Post office vans the reputation will also 1. Direct Rank Computation: In the second step, direct ranking trust computation method is computed by Perron– Frobenius theorem [11] based on message strength [12], each participant vehicle can compute trust value based on the messages received from other vehicles. The computed trust value depends on both the outcome of the message veracity and strength of messages. A vector of ranking value, with positive message strength indicating the strength of the participant vehicle’s transmitted message, then we define a trust computation for participant vehicle as Where is some nonnegative number depending on the outcome of the message transaction between participant vehicle and the participant vehicle , is the total number of vehicles participated in transactions among themselves, and is the number of the message communicated by participant vehicles . If message is communicated just after authenticated by any mechanism in VANET, the value of should be more, after that it should be decreased after a period of time. Another method is to distribute the one value per transaction between vehicles in a continuous, rather than discrete way. One way to assign a value is to distribute the point on the basis of the message strength. If vehicle receives points (weighted sum of correct messages) and points (weighted sum of incorrect messages, (weights being different for correct and incorrect message of same priority)) during a communication session. Then, The direct ranking trust computation is also based on message strength. Indirect Rank Computation: In the last step, the indirect rank computation is based on evaluation the number of authentication certificate exchange at the certain time of vehicles within communication range [13], [14]. If three messages are right out of five messages then source vehicle will increase 1 rank of trust value otherwise indirect rank will decrease 1 rank. In the AHP based trust value of the vehicle is . From the above illustration, it can be observed that the AHP based trust computation can be used to associate trust values with vehicles. The mechanism is able to consider different types of information for computation of the trust values. 4. SIMULATION AND RESULTS In this section, the proposed AHP based trust computation technique for VANET has been evaluated through simulation of real traffic scenarios [15]. A road with multiple unidirectional lanes is considered. Packet length is considered 153 bytes for vehicle to vehicle communication. Packet format is depicted by Figure1 Figure 1. Volume 4, Issue 7, July 2015 Packet structure from vehicle to vehicle communication. Page 198 International Journal of Application or Innovation in Engineering & Management (IJAIEM) Web Site: www.ijaiem.org Email: editor@ijaiem.org Volume 4, Issue 7, July 2015 ISSN 2319 - 4847 The system acts like a queue with increased queuing delay at the vehicle. The computational delay of proposed technique is in order of milliseconds, so proposed technique is based on message exchange delay between vehicles to vehicle communication. The communication delay between vehicle is shown by Figure 2 at the variation of speed of vehicles 10-30 ms-1 and acceleration / deceleration = 3 ms-2 with 300 meter communication range. In this AHP based proposed scheme, computational delay of the vehicle is very less in order of milliseconds, so it is directional proportional to communication delay. Trust computation using AHP based technique is discussed below. If vehicle is public vehicle or not listed in revocation list the trust value of reputation based scheme is 1 In the direct ranking, If vehicle sent safety critical message having strength 5. So, Trust value is 0.875 [12]. Indirect ranking based scheme, if vehicle receives the messages from vehicles within in communication range and receives reputation is 1. If out of 10 vehicles seven vehicle send the same message and if it is right then trust value is increased by 1 value . So, total trust value of AHP method is 3.875. This proposed scheme is lightweight and simple hierarchical process, so, it proves viable and suitable scheme in VANETs. 5. CONCLUSION The present study dealt with the challenge of trust management using AHP based trust computation in VANETs. The scheme is achieved successful trust evaluation system in which multiple techniques for trust computation like the direct interactions, reputation of vehicles based on previous records, availability of forwarded messages, indirect trust computation is used. In future work, we aim to perform experiments to evaluate its performance in real world scenarios. REFERENCES [1] Huibin Xu and DaiWei Wen, “A trust-based routing protocol in VANET,” In IJCSI International Journal of Computer Science Issues, Vol. 10, Issue 1, No 2, pp. 260-263, 2013. [2] Standard Specification for Telecommunications and Information Exchange Roadside and Vehicle Systems- 5GHz Band Dedicated Short Range Communications (DSRC) Medium Access Control (MAC) and Physical Layer (PHY) Specifications, ASTM International, April 2009. [3] Jie Zhang, “A Survey on Trust Management for VANETs: Challenges Desired Properties and Future Directions,” In International Journal of Distributed Systems and Technologies, Vol. 3, No. 1, pp. 48-62, 2012. [4] S. Mazilu, Mihaela Teler and Ciprian Dobre, “Securing Vehicular Networks based on Data-Trust Computation,” In International conference on P2P, Parallel, Grid, Cloud and Internet Computing (3PGCIC), pp. 51-58, 2011. [5] D. Warne and C.P. Holland, “Exploring trust in flexible working using a new model,” In BT Technology Journal, Vol.17, No.1, pp.111-119, 1999. [6] Jie Zhang , “A Survey on Trust Management for VANETs”, in International Conference on Advanced Information Networking and Applications, pp. 105-112, 2011. [7] B. K. Chaurasia and S. Verma “Trust Based Group Formation in VANET,” In International Journal of Modern Traffic and Transportation Engineering Research (MTTER), Vol. 2, Issue 2, pp. 121-125, 2013. [8] A. Boukerche and Y. Ren, “A trust-based security system for ubiquitous and pervasive computing environments,” In Computer Communications, Vol. 31, No. 18, pp. 4343-4351. [9] M. Gerlach, “Trust for vehicular applications,” In Proceedings of the International Symposium on Autonomous Decentralized Systems, pp. 295-304, 2007. Volume 4, Issue 7, July 2015 Page 199 International Journal of Application or Innovation in Engineering & Management (IJAIEM) Web Site: www.ijaiem.org Email: editor@ijaiem.org Volume 4, Issue 7, July 2015 ISSN 2319 - 4847 [10] U. F. Minhas, J. Zhang, T. Tran, and R. Cohen, “Towards expanded trust management for agents in vehicular adhoc networks,” In International Journal of Computational Intelligence Theory and Practice (IJCITP), Vol. 5, No. 1, 2010. [11] J. P. Keener, “The Perron-Frobenius Theorem and Ranking of Football Teams,” SIAM Review, Vol. 35, No. 1, pp. 80-93, 1993. [12] B. K. Chaurasia, S. Verma and G. S. Tomar, “Trust Computation in VANETs”, In the International Conference on Communication Systems and Network Technologies (CSNT-2013), Organized by IEEE, pp. 468-471, 2013. [13] B. K. Chaurasia and R. S. Tomar, “Trust Management Model for Wireless Ad hoc Networks”, In International conference on soft computing for problem solving, K. Deep et al. (Eds.): Proceedings of the International Conf. on SocProS2011, AISC 130, Organized by Springer, Vol. 1, pp. 193-198, 2012. [14] J. J. Haas, Y.-C. Hu, and K. P. Laberteaux, “Design and analysis of a lightweight certificate revocation mechanism for VANET,” In Proceedings of VANET, pp. 89–98, 2009. [15] B. K. Chaurasia, S. Verma, and G. S. Tomar, “Mechanism for Privacy Preservation in VANETs,” In the Journal of International Journal of Grid and High Performance Computing (IJGHPC), Special Issue on: Grid computing and Security, vol. 2, no. 2, 12-22, 2010. Volume 4, Issue 7, July 2015 Page 200