An evolution of a hardware technology makes it possible to deploy lightweight and multi-functional mobile devices in a real environment. Wireless sensor networks (WSN) are representative networks using these tiny and low-power sensor devices. Two types of communications occur in sensor networks: one is between end nodes, and the other is between end node and base station (BS). Since not only the resource-restriction in conventional wireless networks but security-critical applications, security functions are very important issues in WSN. Besides, because of physically low-power facilities in a sensor device, power efficient protocols are essential to maximize a lifetime of networks. In this paper, as the power and security-aware protocol for sensor networks, we propose the transform energy aware security routing (TEASR) protocol. The routing protocol considers mutual authentication of between nodes and an energy information of each nodes. The simulation results maximize a lifetime of networks, and achieve reasonable packet transfer delay.