Research On The Scheduling Techniques Of Security- And Energy-aware Real-time Embedded Systems

With the rapid development of computer network, more and more networked real-time embedded systems are introduced to human’s everyday life. There is no doubt that these systems make our life more convenient. However, close connection to the Internet results in higher possibility of being attacked by hackers. Especially as real-time embedded systems are increasingly applied in the Internet of Things in recent years, failures of the systems are more likely to cause casualties and property loss. So introduction of security service into these systems is necessary. But more security protection means more system load, which makes violation of deadline more possible and thus aggravates risk of system failure. At the same time, energy supply of embedded systems is usually limited. Thus, when strengthening security protection of embedded system, energy constraints must be taken into consideration. To sum up, researchers must tradeoff among system security, real-time requirement and energy efficiency to provide the systems with better protection. And this has become a big challenge.This thesis mainly concentrates in task-scheduling-level optimization of real-time embedded systems while security, energy and real-time of the system are all considered. Static task scheduling is the main topic. In the thesis, the major job is to seek efficient scheduling strategy for real-time tasks, which reinforce systems’ security protection and increase energy efficiency as well, by taking all tasks and available system resource into account.Firstly, the security of two widely used symmetric cryptographies RC5 and RC6 is modeled, and their security performance, corresponding time and energy consumption are quantified by analyzing publicized test data and structure of the cryptographies. Then the security requirements of distributed data collection systems are specified, and the static security-aware scheduling model for security-critical independent periodic tasks is established. After that a security-aware task scheduling algorithm is proposed to achieve the objection of increasing security protection within the constraint of real-time requirement. And finally its effectiveness and limits should be discussed. The thesis also addresses scheduling problems of parallel tasks in distributed security- and energy-critical real-time embedded systems. Firstly the security and energy requirements are analyzed and formulated, based on which the security optimization problem is proposed. And then a Genetic Algorithm based mechanism is derived to handle this problem. This mechanism increases the security protection through two ways, encryption of messages and communication reduction. In the last part of this thesis, the research focuses on security-sensitive mixed-critical real-time system. Firstly the behaviors of mixed security-critical system are formulated. Then the energy optimization problem of security-sensitive mixed-critical systems is proposed and a scheduling mechanism is derived to handle this problem.