| Networks of wirelessly interconnected embedded sensors and actuators promise an unprecedented ability to observe and manipulate our physical world. However as with almost every disruptive technology that has impacted human society, the benefits of embedded networked sensors are accompanied by significant risk factors and potential for abuse. In this dissertation, we focus on the development of high integrity, reliable and secure sensor networks. Sensor networks by their very embedded and collaborative nature are susceptible to novel attacks. The two aspects that make sensor networks unique relative to other networked systems is their reliance on inter-node collaboration, and their coupling to the physical world via the sensors as well as via knowledge of attributes such as absolute and relative location and time. These novel attacks cannot be addressed by developing mechanisms that are solely based on cryptography and authentication. This is in part because of the uncertainties in and lack of control over the physical world and compromised or faulty nodes. To comprehensively address the security problems in sensor networks that go beyond what conventional techniques can handle, this dissertation proposes a new methodology: combining cryptographic mechanisms with robust estimation techniques from signal processing and artificial intelligence together with physics and statistics based models. This approach would not only help counter malicious attacks but also system faults resulting from non-malicious corruptive processes, thus paving the development of trustworthy sensor networks. Based on this approach, this dissertation develops solutions for three security problems of cryptographic key establishment and management, secure time synchronization and resiliency from corrupted data, readings generated by malicious or faulty sensors. |
