The current textbook is about the security in mobile ad-hoc networks by using cryptographic secrete key. Now-a-days security is a major challenging problem in mobile ad-hoc networks because the nodes in mobile ad-hoc networks are moving from one place to another due to this the structure of the network changes frequently. The topology changes may cause "routing modification attack" problem that can easily be exploited against the MANETs. The main goal of routing attacks is to disrupt normal functioning of network by advertising false routing updates. On the other hand data communication attacks include modification or dropping of data packet that does not disrupt routing protocol. In this work, this could be achieved by adding some extensions for secure routing. These extensions include integrity which means the message modification is not allowed and authentication which means the node validation (identification) is done. This protection is provided by a hashed message authentication code function that provides fast message verification and information about sender as well as intermediate node authentication.