In wireless sensor networks clustering is one of the techniques used for energy efficiency. LEACH (Low-energy adaptive clustering hierarchy) is a widely used clustering based routing protocol used for energy efficiency by rotating cluster heads in rounds. But in this protocol, wireless sensor networks are vulnerable to security attacks. To establish security, Secure-LEACH protocol uses shared keys between base station and sensor nodes. These keys are used to generate message authentication code, through which the base station verifies authenticity of the nodes. Secure-LEACH prevents intruders from participating in the network as cluster heads. It also enables the base station to discard any detected bogus messages. Secure-LEACH protects the network from outsider attackers. © Research India Publications.