In this paper, we have discussed a new protocol to authenticate the legitimate coalliary professionals and the sensors in wireless sensor networks. Verifying the authenticity of users and the sensor is one of the most desired requirements of the applications like underground mines to resist the various attacks and preserving the user anonymity so that loss of resources and human casualties occurring in the hostile environment of industries can be minimized. This protocol achieves these security requirements with low cost which saves the lifetime of the devices deployed in critical areas. The mutual authentication and key establishment can also be achieved in our protocol. The formal and informal security analysis of our protocol proves its suitability in the industries like coal mines. Though we have described our protocol by considering its application in coal mines, yet it can be used in all those environ- ments which use similar architecture. In the future, we would like to extend this work in such a way that a registered user can access other gateways and sensors for which he has not registered by acting as a foreign gateway.