Secure Control Protocols for Resource-Constrained Embedded Systems

Koo, Jin Kyu Ph.D., Purdue University, August 2012. Secure Control Protocols for Resource-Constrained Embedded Systems. Major Professors: Saurabh Bagchi and Xiaojun Lin. Embedded systems are increasingly being deployed into the world around us. For example, they are used to monitor the environment around us, measure and control the electrical grid, and control vehicles on the road. As they are integrated in the real world, their security becomes increasingly important. However, due to their lower cost, energy constraints and slow computation speed, maintaining security for these systems is usually very challenging. In this work, we study a range of the important security issues in the operation of embedded systems, which includes reliable synchronization, timely event reporting, and privacy-preserving data transmission. First, we propose a fast and reliable clock synchronization protocol for wireless sensor networks, called CSOnet, which is for wastewater monitoring and is deployed city-wide in a mid-sized US city, South Bend, Indiana. The nodes in CSOnet have a low duty cycle (2% in current deployment) and use an external clock, called the Real Time Clock (RTC), for triggering the sleep and the wake-up. The RTC has a very low drift (2 ppm) over the wide range of temperature fluctuations that the CSOnet nodes operate at, and it has low power consumption (0.66 mW). However, there are two challenges to using RTC for synchronization. First, RTC has a coarse time granularity of only 1 second. Therefore, it is insufficient to synchronize the RTC itself, which would lead to a synchronization error of up to 1 second. Such a large error would be unacceptable for the low duty cycle operation when each node stays awake for only 6 seconds in a 5-minute time window. The second challenge is that the synchronization has to be extremely fast