Security in wireless ad-hoc networks is a complex issue. The wireless and dynamic nature of ad-hoc networks makes them more vulnerable to security attacks when compared with fixed networks. The existing routing protocols are optimized to perform the routing process without considering the security problem.. Black hole attack is one of the routing attacks in which, a malicious node uses the routing protocol to advertise itself as having the shortest path to the node whose packets it wants to intercept. In this paper we propose a certificate based authentication mechanism to counter the effect of black hole attack. Nodes authenticate each other by issuing certificates to neighboring nodes and generating public key without the need of any online centralized authority. The proposed scheme is implemented in two phases: certification phase and authentication phase following the route establishment process of On Demand Multicast Routing Protocol (ODMRP). The effectiveness of our mechanism is illustrated by simulations conducted using network simulator ns-2.

Proceedings ISSN (Online): 1985-2320 This work is subjected to copyright. All rights are reserved whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, re-use of illusions, recitation, broadcasting, reproduction on microfilms or in any other way, and storage in data banks. Duplication of this publication of parts thereof is permitted only under the provision of the copyright law 1965, in its current version, and permission of use must always be obtained from CSC Publishers. Violations are liable to prosecution under the copyright law.

Proceedings ISSN (Online): 1985- 2320 This work is subjected to copyright. All rights are reserved whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, re-use of illusions, recitation, broadcasting, reproduction on microfilms or in any other way, and storage in data banks. Duplication of this publication of parts thereof is permitted only under the provision of the copyright law 1965, in its current version, and permission of use must always be obtained from CSC Publishers. Violations are liable to prosecution under the copyright law.

One main challenge in the design of routing protocols is their vulnerability to security attacks. This is mainly due to the wireless and dynamic nature of ad hoc networks. A black hole attack is a severe attack that can be easily employed against routing in mobile ad hoc networks. In this attack a malicious node advertises itself as having the shortest path to the node whose packets it wants to intercept thereby exploiting the proper functioning of the protocol. In this paper the performance of multicast on demand routing protocols such as Multicast Adhoc On Demand Distance Vector (MAODV) protocol and On Demand Multicast Routing Protocol (ODMRP) are evaluated and analyzed under black hole attack under different scenarios in terms of the performance metrics such as packet delivery ratio and end to end delay. The evaluation is done with network simulator NS-2. Simulation results indicate that both the protocols suffer a significant reduction in packet delivery ratio in the presence of black hole attackers but the impact is more in MAODV when compared to ODMRP due to the presence of alternate data delivery paths in ODMRP.