In the recent years, a lot of research has been carried out in Mobile Ad-hoc Networks (MANETs). The main goals and challenges of security are which characterizes the routing protocol of MANET. Any node can join and leave the network routing protocol which is addressed for only efficient path formation, making the same network vulnerable to various attacks. Associativity-based Routing (ABR) is an on-demand routing protocol, i.e., routes are created only as and when needed. Normally, the routes will be available immediately and the routing tables will be updated constantly among the routes. On-Demand routing is chosen here, because it reduces the control packet traffic which is suitable for wireless network due to limited bandwidth. Protocol's dynamic nature enables MANET operation ensuring deployment in extreme/volatile circumstances. This paper proposes an Extended Public Key Cryptography (EPKCH) system. This cryptosystem is mainly designed for securing data during packet forwarding operation and also to detect malicious and selfish nodes during network initializing and packet forwarding operation. Confidentially is the basic feature provided by the public key cryptography, which also provides authentication, non-repudiation and integrity. The protocol is designed to protect the network from malicious and selfish nodes. An extended public key cryptography mechanism is implemented in ABR, in order to achieve security goals for the following parameters Path-Division Routing (PDR), Routing overhead, delay, on-demand routing, packet loss and throughput. The proposed model is stimulated using Network Simulated (NS2).