An ad hoc network is a collection of autonomous mobile nodes to forming an instant multihop radio infrastructure-less network in a dynamic topology. Many routing protocols for mobile ad-hoc networks are presented since last decade.Ad-hoc networks are in a great demand now a days and have a lot of advantages.In this direction, we have designed the Ad Hoc On Demand Routing Protocol (AODV) using Network Simulator (NS) which is efficient as well as we have implemented the security technique so the we can prevent the data loss at the time of transmission. The main advantage of using the Network Simulator for the design of AODV is that we can actually observe the working of the specific protocol without the establishment of the network as NS provides the environment for the working of protocol. In this paper, we provided the security to the AODV routing protocol using asymmetric Cryptography with the help of RSA algorithm.