Abstract: Privacy is needed in adhoc networks. A Secured on demand position based private routing algorithm is proposed for communication anonymity and provide a security in mobile Adhoc network. Here we use cryptography algorithm for providing security to prevent message hacking information from internal and external attackers. The position information of nodes is drawn by GPS (Global Positioning System). Here, we provide a terminal node behave like server to getting position information of nodes in the network. A Simulator based on GLOMOSIM is developed for evaluating security. It provides a secure data transmission between the nodes. In our design, the server with the process of GPS system records all the information about the terminal nodes involved in the Ad-hoc networks. This server will send the Position Reply (PREP) to the source when it receives the Position Request (PREQ). This PREP is encrypted to provide the security and it�s transmitted to all the intermediate nodes in the Ad-hoc networks and the intermediate performs decryption and gets the destination address. The intermediate nodes checks with its own address and if it matches it request for the data and it sends Node Reply, else it will again sends the PREP to all the other intermediate nodes. This Node Reply is then analyzed to find the optimal route. In this paper we proposed a new protocol using Cryptographic techniques. GLOMOSIM-(A Global mobile simulator) is developed for evaluating the security.