Wireless Sensor Networks (WSN) is an emerging technology for attraction of researchers with its research challenges and various application domains. Today, WSN applications can be used in environmental detection, Monitoring system, medical system, military and industrial monitoring for ability to transform human life in various aspects. Depending on applications used for WSNs, security is the biggest challenges in WSNs and security aspect is essential for WSNs before designing WSNs. The routing protocols for WSNs need security services for transmission exact and secure data to the users through the network. LEACH (Low Energy Adaptive Clustering Hierarchy) is a routing protocol used in WSNs by arranging sensor nodes into clusters. Every sensor cluster is managed by a Cluster Head (CH) during the network operation such as routing and data aggregation from Cluster Member (CM). Therefore, security and authentication is necessary between CH and CM. However, LEACH is lack of security. This paper presents integration of security and authentication between CH and CM on LEACH routing protocol. For the implementation of this integration, NS-2 simulation software is used and it is necessary to combine security agent into NS-2 tool for WSN. But currently, NS-2 does not support these features. Therefore, the main aim of this paper is to develop security and authentication agent into NS-2 and LEACH protocol for WSNs with the simulation results.