Abstract-Embedded systems, particularly real-time systems with temporal constraints, are increasingly deployed in every day life. Such systems that interact with the physical world are also referred to as cyber-physical systems (CPS). These systems commonly find use in critical infrastructure from transportation to health care. While security in CPS-based real-time embedded systems has been an afterthought, it is becoming a critical issue as these systems are increasingly networked and inter-dependent. The advancement in their functionality has resulted in more conspicuous interfaces that may be exploited to attack them.In this paper, we present three mechanisms for time-based intrusion detection. More specifically, we detect the execution of unauthorized instructions in real-time CPS environments. Such intrusion detection utilizes information obtained by static timing analysis. For real-time CPS systems, timing bounds on code sections are readily available as they are already determined prior to the schedulability analysis. We demonstrate how to provide micro-timings for multiple granularity levels of application code. Through bounds checking of these micro-timings, we develop techniques to detect intrusions (1) in a self-checking manner by the application and (2) through the operating system scheduler, which are novel contributions to the real-time/embedded systems domain to the best of our knowledge.

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In this paper we present a method for improving the precision of an RSSI-based energy-constrained localization system employed in an IEEE 802.15.4 sensor network. The goal application is localization of people in dynamic indoor environments. We introduce an approach which divides the anchor nodes into groups and assigns a path loss exponent to each group. The results from the conveyed tests in our building show a location error smaller than 3m, despite the low energy constraints. Moreover, we provide a hardware platform independent system suitable for both standard and proprietary solutions