A cross-layer defense scheme for countering traffic analysis attacks in Wireless Sensor Networks

In most Wireless Sensor Network (WSN) applications the sensors forward their readings to a central sink or base station (BS). The unique role of the BS makes it a natural target for an adversary´s attack. Even if a WSN employs conventional security mechanisms such as encryption and authentication, an adversary may apply traffic analysis techniques to locate the BS. This motivates a significant need for improved BS anonymity to protect the identity, role, and location of the BS. Published anonymity-boosting techniques mainly focus on a single layer of the communication protocol stack and assume that changes in the protocol operation will not be detectable. In fact, existing single-layer techniques may not be able to protect the network if the adversary could guess what anonymity measure is being applied by identifying which layer is being exploited. In this paper we propose combining physical-layer and network-layer techniques to boost the network resilience to anonymity attacks. Our cross-layer approach avoids the shortcomings of the individual single-layer schemes and allows a WSN to effectively mask its behavior and simultaneously misdirect the adversary´s attention away from the BS´s location. We confirm the effectiveness of our cross-layer anti-traffic analysis measure using simulation.