ARCSM: A Distributed Feedback Control Mechanism for Security-critical Real-time System

Since the real-time systems are becoming increasingly networked, there are some growing critical challenges of security management and risk control. For the unpredicted and especially unsecured environments, such security-critical distributed real-time embedded systems need to enforce security on multiple nodes in order to against the potential threats as well as satisfying the real-time requirements. Unlike the traditional ad hoc static designing approaches, based on feedback theory, this paper proposes an Adaptive Risk Control and Security Management (ARCSM) mechanism for centralized distributed systems. ARCSM has the ability to guarantee the soft real-time and provide as strong security protection as possible. To meet this requirement, the host server is able to refuse to serve for the deadline missed tasks. In each node, a two-level scheduling framework is designed to implement the feedback control twice. In the first feedback, an appropriate initial security level is assigned for new task. At the runtime, the second feedback can dynamically adjust the ready tasks´ security level based on runtime status. Considering features of embedded systems, we measured the energy and time costs of cryptographic algorithms and established a method to quantify the security risk. Moreover, the relationship between time and energy costs analyzed in this paper leaves its significance for the future researches. Experimental results demonstrate that our mechanism can be adaptive to the fluctuation of input workloads and has better performance than open-loop schemes.