Abstract—Vehicular Ad Hoc Network (VANET) is achallenging area of research in the field of vehicular technology.It is an emerging topic for its high mobility and high link disruption. But if link disruption is due to the malicious drivers in the network then it reduces the performance of the network. Hole Generation attack is a kind of attack in which the malicious drivers breaks the communication links between the vehicles by increasing or decreasing their own speeds when they are a part of the network. In this paper, we proposed a Robust Routing Protocol (RRP) to send the message securely from source to destination by surviving from the hole generation attack. RRP consists of a security module to recognize a genuine node and arecovery module to resist the hole created by the malicious drivers. RRP network model is mainly divided into three phases: first phase is the hole detection phase in which the hole is detected, in the second phase hole information is broadcasted in the whole network and in the third phase the data is transmitted from source to destination by selecting a secure optimal path. Simulation result shows RRP performs better than GPSR when security and recovery is considered. It has a high packet delivery ratio when malicious drivers are considered in the network.

Index Terms—Hole Generation Attack, RRP, Security, Simulation, VANET

I. INTRODUCTION

ANET [9], [15], [19] is a new generation advance network developed by using wireless technology to

provide faster communication between the vehicles in the city roads. For the development of VANET, many new types of protocols, architecture, designs, etc. are implemented in theurban areas.

The main objective of using VANET is to reduce the accident levels in the roads, highways, city areas, etc. This is the main goal of VANET by which it provides safety to the end users. By using this network one can download media files, use TCP/IP services, control the traffic, etc. It has many applications for the drivers and passengers but the mainapplication is to manage the traffic smoothly. VANET has been deployed in many countries like European Union, USA

S. K. Bhoi, R. P. Nayak and D. Dash are with Department of Computer Science & Engineering, National Institute of Technology, Rourkela-769008,India (email: souravbhoi@gmail.com; rajendra.cet07@gmail.com;debasis.nitrkl@gmail.com).J. P. Rout is with Department of Computer Science & Engineering, Kalinga

Institute of Industrial Technology University, Bhubaneswar- 751024, India (e-mail: jyotiprakash.jpr@gmail.com).

and Japan [2]. Many projects are running in these countries to provide security and safety to the end users [9]. WAVE, IVI, VII, VSC, etc. are some the projects running in USA. JAPAN has many projects like ASV-2, JARI, DEMO, etc. and European Union uses the VANET services (ITS) in a huge amount and it has projects like C2C-CC, Fleetnet, PreVent, NoW, etc. These projects mainly aim to provide better services to the users and reduce the accidents.

Security [13], [14], [16] in VANET is a major problem which degrades the network by making it vulnerable to many threats. VANET is affected by many malicious nodes in the network. Attacks in the network are mainly divided into activeattacks and passive attacks [18]. Black hole attack, Sinkhole attack, spoofing, position cheating [7], [8], [12], data modification [1], etc. are some of the frequent attacks in VANET. In this paper, we mainly concentrates on the hole generation attack, in which the malicious drivers inside the network breaks the links by reducing their own speed or boosting their speed to create holes.

In this paper, we proposed a Robust Routing Protocol (RRP) to send the message securely from source to the destination by surviving it from hole generation attack. RRP consists of a security module to recognize a genuine node and a recovery module to resist the hole created by the malicious drivers.

The paper is presented as follows: section 2 presents the related work done on VANET routing and recovery. In this section GPSR hole recovery is discussed HRR routing protocol is discussed. Section 3 presents the proposed RRP routing protocol. Section 4 presents the simulation results and at last we conclude in section 5.

II. RELATED WORK

Currently routing is a major area of research in ad hoc network to develop an optimal and efficient routing protocol. Many routing protocols [4], [6], [11], [20] are designed for MANET and implemented in VANET, but because of its high mobility and frequent link disruption it is difficult to implement these protocols. So, the topology based protocols used in MANET are unreliable for VANET systems. VANET routing protocols [9] are mainly divided into topology based, cluster based, position based, geocast based and broadcast based routing protocols.

For recovery against holes many routing protocols are

Sourav Kumar Bhoi, Student Member, IEEE, Rajendra Prasad Nayak, Debasis Dash and Jyoti Prakash Rout

RRP: A Robust Routing Protocol for VehicularAd Hoc Network against Hole Generation Attack

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International conference on Communication and Signal Processing, April 3-5, 2013, India

978-1-4673-4866-9/13/$31.00 ©2013 IEEE1175

developed like Face Routing [4], GPSR [21], HRR [5], etc. in face routing it uses the left hand rule and right hand rule techniques to send the data to the destination, but the path becomes too long and time taking. Karp et al. [21] proposed GPSR routing protocol which provides a recovery module by using right hand rule against the hole and uses planar graphsfor checking.

Peiqiang et al. [5] proposed HRR routing protocol in which firstly the hole is detected and then hole information is broadcasted in the network. By this one can bypass the hole and reach the destination. It is more efficient than GPSR because each node knows the position of the hole and decidesaccording to situation and passes the hole. It uses ellipse to know the boundary of the nodes and decides the path to the destination. RRP has many advantages over GPSR routing protocol when malicious drivers are also in the network by creating holes. The concepts of hole detection and hole broadcasting used in first phase and second phase respectively is adapted from [5].

III. PROPOSED RRP PROTOCOL

RRP routing protocol is mainly designed to send the data from source to the destination through a secure optimal path. The main objective of RRP protocol is to survive against the hole generation attack. This section describes about the network model, hole generation model and phases of our algprithm.

A. Network ModelRRP network model mainly consists of vehicles, roads,

RSUs, CA and CU. The assumptions taken to build the network are discussed as follows: each node in the network is responsible for communication. Vehicles contain high battery power. Vehicles are installed with GPS by which they can know their own position by using the maps and can trace other vehicles position. All vehicles beacons at a particular interval to update the location information of other vehicles. Each vehicle in the network has its own id. Hole generation attack is considered in the network in which some malicious vehicles breaks the links between the vehicles.

RRP routing model mainly consists of three phases: hole generation phase, hole broadcasting phase and secure optimalpath generation phase. Figure 1 presents the three phases used by RRP to transmit the data from source to the destination.

Fig. 1. Network Model for RRP

B. Hole Generation Attack ModelHole generation model describes how the malicious drivers

create holes in the network. Figure 2 shows the presence of malicious drivers and figure 3 shows how the drivers are creating the hole by increasing or decreasing their own speeds by changing their location from (X1,Y1) to (X1’,Y1’) and from (X2,Y2) to (X2’,Y2’).

Fig. 2. Network Model with malicious drivers

Fig. 3. Malicious drivers changing their locationsThe main causes of hole generation attack are discussed as

follows: 1) Case 1: Some imposter nodes are responsible for Hole

Generation

Fig. 4. Hole generated by some malicious drivers

2) Case 2: All imposter nodes are responsible for Hole Generation

Fig. 5. Hole generated by all malicious drivers

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Figure 4 and figure 5 shows how the hole is generated by the malicious drivers.

C. Phases of RRP ProtocolThe phases of RRP routing protocol are described as

follows:1) Hole Detection Phase: A node initializes (BN0) the boundary detection by assuming itself in the boundary and send H to other boundary NN. The boundary nodes communicate and collaborate with each other to find the boundary (hole). BN0 sends H to next BN, then the next BN sends H by storing its location in the H packet. This process continues by taking the LHR and when BN0 is reached, the boundary is detected. Figure 6 shows the packet format received at BN0 and figure 7 shows how the packet is received by taking LHR path in the boundary. The malicious drivers cooperate to find the hole because they want to send the packet through the left boundary or right boundary and so that they will perform selective forwarding by dropping the packets.__________________________________________________Algorithm 1: Hole Detection Phase__________________________________________________Notations:

IN: Initializing Node (BN0)H: Hello packetBN: Boundary Nodes (BN0, BN1, BN2, BN3,,…,BNn)NN: Neighboring Nodes (NN0, NN1, NN2, NN3,,…,NNn)L: Location ((x1,y1),……,(xn,yn))N_BN : Next Boundary Node LHR: Left Hand Rule

1. IN initializes the communication2. if(NNn==BN) // where NN=N_BN of BN0

{ Send H;

// IN (BN0) sends H to BNn by using LHR }3. Record the L of BNn and send to N_BN 4. step 3 continues until BN0 is reached5. Hole is detected________________________________________________

Fig. 6. Packet received at BN0

Fig. 7. Hole Boundary Detection by BN0

2) Hole Information Broadcasting Phase: Hole information is broadcasted in the network to aware other nodes about the location of the boundary nodes. Figure 8 shows the Broadcasting of hole information by BN0._________________________________________________Algorithm 2: Broadcasting Hole Information_________________________________________________Notations:N: Node in the network (N1,……,Nn)BIN: Boundary Information (BN0, BN1, BN2, BN3,…,BNn)1. BN0 broadcasts the hole information (BIN) in the network2. Each Nn in the network is aware of the hole information __________________________________________________

Fig. 8. Broadcasting of hole information by BN0

3) Secure Optimal Path Generation: S initializes the communication by sending M to D by using a secure MFR routing protocol. This process continues until hole is reached. After reaching the hole it recovers by creating two lines d1 and d2 from BN0 by intersecting perpendicularly l1 and l2. l1 and l2are the lines parallel to each other and they are created on the top most and bottom most points of the boundary. Then ED is calculated and if d1<d2, path is selected in the left boundary by LHR in D’s direction else path is selected in the right boundary by RHR in D’s direction. Path is selected in the boundary because it is the optimal route to reach D.

After selecting the routes direction each node again use secure module to send M. If a node in the boundary is malicious then it uses the recovery module by finding Nearest_NN in D’s direction and applying Secure( ) between BNn and NNn and then again applying Secure( ) between that NNn and N_BNn (tying to enter the boundary because it is the shortest path to reach D). After hole is passed it again uses the secure MFR routing protocol. __________________________________________________Algorithm 3: Secure Optimal Path Generation __________________________________________________Notations:S: SourceD: DestinationMNn: Malicious Nodes (MN1,…………..,MNn)l1 and l2: lines perpendicularly intersected by d1 and d2d(u,v): distanced1 and d2: Distances from node IN (BN0) to l1 and l2RHR: Right Hand RuleLHR: Left Hand RuleNearest_NN: Nearest Neighboring Nodec1 and c2: Challenge send from N1 to N2

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Si: SignatureM: Messaged: private key of N1n: large prime number(e,n): public R: Request to send M

Send( ){

M, Si N1 → N2

// N1 sends M and Si to N2// Si=Mdmod n }

Secure( ){

c1 1. N1 → N2 // N1 sends c1 to N2

c2, N2’s certificate2. N2 → N1 // N2 sends c2 and N2’s certificate3. N1 verifies N2’s certificate N1’s certificate3. N1 → N2 // N1 sends certificate to N24. N2 verifies N1’s certificate5. N2 sends R to send M6. if(step 1 to 5 == true) Send( );

else choose another NN;

}

Recovery( ){

1. Find Nearest_NN in D’s direction2. Apply Secure( ) between BNn and Nearest_NNn3. Apply Secure( ) between that Nearest_NNn and N_BNn

// trying to return to the boundary path }

1. S initializes the communication by using MFR routing protocol

2. Apply Secure( )3. Repeat step 1 and 2 in D’s direction4. if(BIN in a Nn==Nn’s NNn) // where Nn’s NNn=BN0

hole reached;// recovery starts from step 5

5. Draw two || lines l1 and l2 from the top point of the hole and bottom point of the hole

6. Create d1 and d2 from BN0 by intersecting perpendicularly l1 and l2

7. Calculate d1 and d2 by using Euclidean Distanced(u,v)=√((u-u1)2 + (v-v1)2)// (u,v)=L of BN0 and (u1,v1)=L of intersecting point

8. if(d1<d2)Path is selected in the left boundary by LHR in D’s

direction;else

Path is selected in the right boundary by RHR in D’s direction;

9. Apply Secure( )10. Repeat step 9 11. if(step 10 fails)

Recovery( );12. if(hole is passed)

apply MFR by using Secure( ) and send M to D;13. End

__________________________________________________

Fig. 9. Illustration of data transmission to D by passing through the hole

Illustration in figure 9 shows how the data is passed to D by surviving from the hole generation attack. When BN0 is reached, it selects BN0→BN1→BN2→BN3→BN4 path to reach the destination, but the left boundary selected has a malicious driver BN2 which can perform selective forwarding.BN1 chooses BN2’ as its NN to send M by using security function. Then BN2’ tries to enter the network by sending M to BN3. It tries to pass through the boundary because it is the shortest and optimal path to send M to D.

IV. SIMULATION & RESULTS

The performance of RRP routing protocol is compared to GPSR routing protocol. Simulation result shows RRP routing protocol has a better packet delivery ratio as compared to GPSR when malicious nodes are considered in the network. The end-to-end delay is high for RRP because security module is used to send M to D. Parameters taken to simulate RRP isshown in table 1. Figure 10 and figure 11 shows the packet delivery ratio and End-to-End delay respectively.

TABLE ISIMULATION SETUP

Parameters Values Set

Area 1000 m * 1000 m

MAC Protocol IEEE 802.11 DCF

Packet Size 512 Bytes

Transmission Range 300 m

Traffic CBR

No. of Senders 25

No. of Malicious Nodes 5-25

Speed 30-60 Km/H

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Fig. 10. Packet Delivery Ratio

Fig.11. End-to-End Delay

V. CONCLUSION

RRP routing protocol shows better performance then GPSR routing protocol and HRR routing protocol when security is considered in the network. In this protocol, recovery module is used two times to resist the hole. This not only increases the security in the network but also helps to find the optimal path to reach D. RRP performs better than GPSR in packet delivery ratio and it has high end-to-end delay due to the use of security module. As hole information is known by each node in the network they can bypass the node as well as pass through the boundary of the hole. Further we will implement RRP routing against more attacks.

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