VEBEK: Virtual Energy-Based Encryption and Keying for Wireless Sensor Networks

Designing cost-efficient, secure network protocols for Wireless Sensor Networks (WSNs) is a challenging problem because sensors are resource-limited wireless devices. Since the communication cost is the most dominant factor in a sensor´s energy consumption, we introduce an energy-efficient Virtual Energy-Based Encryption and Keying (VEBEK) scheme for WSNs that significantly reduces the number of transmissions needed for rekeying to avoid stale keys. In addition to the goal of saving energy, minimal transmission is imperative for some military applications of WSNs where an adversary could be monitoring the wireless spectrum. VEBEK is a secure communication framework where sensed data is encoded using a scheme based on a permutation code generated via the RC4 encryption mechanism. The key to the RC4 encryption mechanism dynamically changes as a function of the residual virtual energy of the sensor. Thus, a one-time dynamic key is employed for one packet only and different keys are used for the successive packets of the stream. The intermediate nodes along the path to the sink are able to verify the authenticity and integrity of the incoming packets using a predicted value of the key generated by the sender´s virtual energy, thus requiring no need for specific rekeying messages. VEBEK is able to efficiently detect and filter false data injected into the network by malicious outsiders. The VEBEK framework consists of two operational modes (VEBEK-I and VEBEK-II), each of which is optimal for different scenarios. In VEBEK-I, each node monitors its one-hop neighbors where VEBEK-II statistically monitors downstream nodes. We have evaluated VEBEK´s feasibility and performance analytically and through simulations. Our results show that VEBEK, without incurring transmission overhead (increasing packet size or sending control messages for rekeying), is able to eliminate malicious data from the network in an energy-efficient manner. We also show that our framework performs be- - tter than other comparable schemes in the literature with an overall 60-100 percent improvement in energy savings without the assumption of a reliable medium access control layer.