With the rapid development of embedded systems, users and services have been greatly facilitated while also experiencing security threats as a result of cyber-attacks and system vulnerabilities. Currently, the real-time embedded system (RTES) focus is to deal with these security issues. In this paper, we introduce a short review of security-aware techniques for RTES. We mainly discuss two common approaches to improve the security of RTESs. The first approach is achieved by exploring specific attacks. The second approach is realized by deploying security-guaranteed services. However, improving the security of embedded systems may cause excessive energy consumption at the same time. Therefore, we investigate the secure and energy-aware RTESs on a wide range of research. In addition, we study a number of common applications used in secure RETSs. This paper stands for providing awareness and better understanding of the current RTES research status as well as technical theory behind it. Hence, the RTES security issues are resolved.

Unlike traditional embedded systems that almost have only one criticality level, many complex embedded systems nowadays are mixed-critical and are more and more widely used. There has been a lot of research on mixed-criticality (MC) systems. In this paper, we present a survey on the MC systems on these research. First, we discuss the exaltation of the schedulability of MC systems. As improving schedulability may lead to quality-of-service (QoS) reduction of MS systems. Therefore, we investigate the approaches to solve this problem. Improving QoS of MS systems may inevitably increase the energy consumption. Then, we introduce the researches that take the energy efficiency as a design requirement of MC systems. Few MC systems regard fault-tolerance as the design requirement, thus, we extensively investigate fault-tolerance of MC systems. In addition, we introduce some of the main applications for MC systems.