INVENTION OF GAMMA PROTOCOL FOR VANET USING MODULAR ARITHMETIC TECHNIQUES

: Vehicular Ad Hoc Networks (VANETs) are the promising approach to provide traffic, safety and other applications to the drivers as well as passengers. It becomes a key component of the intelligent transport system. Moreover, the security of vehicular ad hoc networks (VANETs) has been receiving a significant amount of attention in the field of wireless mobile networking because VANETs are vulnerable to malicious attacks. Proposed Gamma protocol not only adapts the concept of Transitive Trust Relationships but also improves the performance of the authentication procedure and it provides fast communication with good security than other existing systems. NS2 is open source and discrete event-driven, object-oriented and freely available simulation tool to simulate and analyse dynamic nature of communication networks; it is also a powerful tool to develop new protocols and functions. It provides support for OSI and TCP/IP protocols stack and many standard routing and application protocols for wired and wireless networks. NAM is used to display the process of simulation. We implement Gamma protocol in NS2 Simulator.


INTRODUCTION
VANET is a network of vehicles and infrastructure points. It consists of number of reliable sensors within it for communication. The primary goal of VANET is to provide road safety conditions to drivers as well as passengers in emergency situations [1]. In VANET, a modern vehicle communicative parts are as follows: A major drawback of VANET is achieving data dissemination and fast communication [12] so that computation cost and storage space is low. In order to decrease drawback in VANET, many schemes emerged [1]- [15]. Unfortunately, all these schemes lead to high storage cost with slow communication. So, to achieve fast communication, we propose a scheme called Gamma Protocol by using modular arithmetic techniques. The architecture of VANET [3] consists of mainly OBUs (On-Board Units) and RSUs (Road Side Units).OBUs are installed so that each vehicle communicate with each other by using authentication point or RSU. GPS antenna is used for obtain information about places and traffic details. Base stations are deployed in order to access the information. According to the IEEE 802.11p the communication among vehicles can be classified as: V2V and V2I. If there is communication among vehicles then it is said to be V2V, and if there is communication among vehicles and infrastructure then it is V2I. In VANET a base station is not dynamic, so in order to achieve authentication among all vehicles we use Transitive Trust Relationships concept which is very important concept in VANET. In VANET, vehicles can be classified as [19]: (1) LE (Law Executor): It can authenticate nearby normal vehicles. It will always act as a permanent TV.
(2)MV (Mistrustful Vehicle): If communication between LE and normal vehicle, then normal vehicle will be turned into TV, otherwise it will be as MV. A MV is nothing but a normal vehicle.  The remainder of this paper is organized into as follows: Section II contains a review of related work. Section III explains problem statement, section IV gives proposed work.In Section V, we give the analysis and simulation results. In section VI, we give conclusion. In section VII, we give acknowledgment and at last, references are given which are used for preparing this paper.

RELATED WORK
It has been demonstrated that problem of VANET is vehicle protection from theft, prevention from sudden accidents, unwanted malicious attacks, communication with other vehicle in a secure way. It means, achieving secure communication among nodes is must to prevent such attacks. So, many schemes emerged to achieve secure communication among nodes. Raya and Hubaux [1] preloaded each vehicle with a large number of anonymous public and private key pairs. However, this approach works good but with high computation cost, high storage space, and high communication overhead. And also, this scheme is not suitable for highly dynamic environments like VANETs. Zhang [7] proposed a RSU-based message authentication scheme, which uses the symmetric key hash message authentication code, instead of a PKI-based message signature, in order to reduce the signature cost which results in low storage space. However, this method also leads to a high computation cost. Gowtham [17] achieved communication between nodes take place in secured way by using security algorithms similar to ECDSA and TESLA. VANET uses a hardware known as TPD to provide security to nodes [20] in communication process. For sample example please refer [22] Jae Chang and Mark Claypool explained example. To achieve fast communication with security is one of the major problems in VANET. So, in order to achieve fast and secure communication many schemes emerged by using many methodologies. From these, ECC [23] method by Menezes, S. Vnstone, and D. Hankerson achieved best security but with high computation cost. So, in order to overcome this disadvantage, Sirwan A Mohammad and Dr. Sattar [24] developed wireless network based on ns2. But, unfortunately, this scheme also leads to high storage space and also to achieve general authentication in this scheme, requires many steps. From these all schemes, a scheme proposed by Zhang [7] which uses symmetric key hash function and Trust Extended Authentication Mechanism by Ming-Chin Chuang and J.-F. Lee [25] by using XOR operation are best schemes. But, these schemes lead to long authentication latency.So, in order to overcome this drawback, we proposed a scheme called Gamma Protocol Using Modular Arithmetic techniques.

3.PROBLEM STATEMENT
Security is major problem in VANET because it can be easily attacked by attackers. Therefore, there is a need for efficient and robust authentication scheme. So, in order to achieve better authentication for VANET many schemes emerged. But all of these schemes have some problems.In all these base schemes, main problem was all responsibility goes to LE. If LE is malicious node then calculations of network groups are going to be wrong, mainly storage space,computation costcalculationsare very high. Hashing method introduced in VANET works in excellent manner, but its keys are easily attacked. Hence, there is a need for an efficient, robust and secure authentication scheme for VANETs with low computation cost, low storage space and short authentication latency. So, in order to give fast and reliable security, we provide Gamma Protocol which uses RSUs-based and on modular arithmetic techniques.

PROPOSED WORK
Number theory plays an important role in cryptography. Modular-arithmetic-based concept is the central mathematical concept in number theory. Modular arithmetic approach was developed by Carl Friedrich Gauss. "Modulus" (abbreviated as "mod") is the word for "residue or remainder". The difference between normal arithmetic and modular arithmetic is that modular arithmetic operations are performed regarding a positive integer where numbers "wrap around" upon reaching a certain value i.e. "mod". In VANET, asymmetric key is better than symmetric key if only there will be fast communication and short communication latency.Best examples to public key cryptography algorithms are RSA and DHA. In modular arithmetic operations, multiplication operation i.e. mod multiplication is much more secure. So, in asymmetric key, we use modular arithmetic techniques very much. Gamma Protocol also uses asymmetric key and mod multiplication operation. Consider two nodes under same network under one topology want to communicate with each other to achieve fast communication , then they select one prime number such that prime number greater than zero. And select one primitive root of that prime number such that, that primitive root is less than the chosen prime number. After they select two secret keys and compute respective public values. Here, they exchange these public values and compute common keys by using modular arithmetic techniques. This step gives moresecurity. If that keys are equal, then vehicles behave like TVs and authenticate nearby vehicle to make turn that vehicle into TV. Thus all vehicle communicate with each other after turning into TV, otherwise they behave as MV i.e. Normal vehicle. Thus whole network will be formed for fast communication.

A. Software Testingand Implementation
A network simulator predicts the behavior of a computer network environment and it gives accurate understanding of system behavior. It is designed specifically for research in computer communication networks [26]. So, we can say the network simulator is the bank of different network and protocol objects [25]. NS2 is one of the most popular simulators used in network research. It is open source and freely available software and developed at the University of Berkeley.It is available for platforms FreeBSD, Linux, SunOS/Solaris, MAC OSX and all windows versions. In ns2 simulator, network protocol stack is written in C++ language for fast to run, OTCL for fast to data write in order to differentiate control and data path implementations. TCL scripting language is used for specifying scenarios, traffic patterns and events. We carefully analysis the trace files for calculating the performance of network protocols.  Xgraph is X-windows application and analysis tool used for seeing simulation results in the form of graph i.e. to plot the characteristics of NS2 parameters like throughput, End-to-End Delay and packet loss etc...

SIMULATION RESULTS
In this section, we analyze the performance of Gamma Protocol and see the simulation results in Xgraph. We used five different source codes, DropTail queuing mechanism and AODV Routing Protocol.

A. Throughput
It is defined as rate of successful message delivery over a channel or aggregate number of packets delivered over the simulation time. Mathematically it can be written as: Throughput=N/100 Where N is the number of bits bought by all destinations. Figure 11. Throughput Graph.

B. End-to-End Delay
It is defined as time taken for a packet to be transmitted successfully across a network from source to destination. Mathematically it is defined as: Where AED is average end to end delay t i (r) is the receiving time of packet I by the destination node, t i (s) is the sending time of packet i by the source node and n pr is the total number of packets received.

C. Packet Loss
It is defined as number of failed packets to reach destination from source during transmission. Packet loss occurs due to network congestion. Mathematically it can be calculated as: Packet Loss= Where N is packet lost and s is the packet sent. Figure 13. Packet Loss Graph.
From the results obtained, it is concluded that Gamma Protocol is better than base methods which are existed before this protocol.

CONCLUSION
Fast communication and security are the major achievements for implementing the VANET. In this paper, we study the proposed scheme called Gamma Protocol to protect valid users in VANET and fast communication requirements. Confidentiality is not required in the VANET because generally packets on the network do not contain any confidential data. The amount of cryptographic calculation under proposed scheme was substantially less than in existing schemes. Moreover, Gamma Protocol is based on the concept of transitive trust relationships to improve the performance of the authentication procedure. In addition, Gamma Protocol has a few storage space to store the authentication parameters than existing system.