The Wireless Identification and Sensing Platform (WISP) from Intel Research Seattle is an instance of Computational RFID (CRFID). Since WISP tags contain sensor data along with their IDs, the authentication of these tags should be different than the ones found in typical RFID networks. Moreover, there can be a situation where an adversary may create more collisions at the link layer to initiate the de-synchronization attack. This in turn may result in DoS attack or system failure and may increase the system response time. In this paper, we propose a De-synchronization attack resistant Robust Authentication Protocol (DRAP) for WISP networks. Our proposal offers a lightweight solution to defend against major security attacks, including de-synchronization and DoS attacks. This protocol can return desynchronized tags and readers to their synchronous state. Therefore, it provides robustness and ensures survivability. We evaluate DRAP protocol in a simulated WISP environment and report the results in this paper.