Securing Mobile Unattended WSNs against a Mobile Adversary

One important factor complicating security in Wireless Sensor Networks (WSNs) is lack of inexpensive tamper-resistant hardware in commodity sensors. Once an adversary compromises a sensor, all memory and forms of storage become exposed, along with all secrets. Thereafter, any cryptographic remedy ceases to be effective. Regaining sensor security after compromise (i.e., intrusion-resilience) is a formidable challenge. Prior approaches rely on either (1) the presence of an on-line trusted third party (sink), or (2) the availability of a True Random Number Generator (TRNG) on each sensor. Neither assumption is realistic in large-scale Unattended Wireless Sensor Networks (UWSNs) composed of low-cost commodity sensors. periodic visits by the sink. Previous work has demonstrated that sensor collaboration is an effective, yet expensive, means of attaining intrusion-resilience in UWSNs. In this paper, we explore intrusion resilience in Mobile UWSNs in the presence of a powerful mobile adversary. We show how the choice of the sensor mobility model influences intrusion resilience with respect to this adversary. We also explore self healing protocols that require only local communication. Results indicate that sensor density and neighborhood variability are the two key parameters affecting intrusion resilience. Our findings are supported by extensive analyses and simulations.