Mobile ad-hoc network (MANET) is a collection of mobile nodes which do not have any infrastructure, i.e., access points. Designing an efficient authentication mechanism for such a large mobile network is challenging task as the nodes have limited battery and bandwidth constraints. There are different types of attacks which consume resources of the whole network and hence disrupt the routing process. This paper proposes an authentication technique without use of any trusted third party (TTP) or Certifying Authority (CA). Clustering provides an effective way to divide network to make the areas within which routing is performed and overhead is also reduced. For mutual authentication of nodes, clustering is used with keys and unique identity numbers together provides authentication and the cluster heads will account for mobility. This will restrict the malicious nodes to enter into the network and thus reduces the chances of attack.