# The Integration of Azure Sphere and Azure Cloud Services for Internet of Things
## 2 Related Work  
### Security Research in IoT Systems  
Currently, there are two main research topics involving IoT system's security. The first one is the security schemes and policies for resource-constrained IoT systems, while the second one is the design and implementation of security solutions for IoT applications [8]. The research on the first one is currently directed at four critical areas including access control schemes, anomaly detection, security models and key management to achieve the high levels of security. Firstly, for access control schemes in IoT, a large and intensive research effort is devoted to the access control architecture, the type of keys used to secure the communication channel, the access control channel, and the access control logic [18]. In addition, such access control schemes are widely used in implantable medical devices [19], body area networks [20], smart gird with renewable energy resources [21], smart home [22], and industrial networked systems [23]. Secondly, in order to achieve the automatic identification of resource depletion and unauthorized access, anomaly detection is proposed, which is generally categorized into three different ways, namely, unsupervised anomaly detection [24], supervised anomaly detection [25] and semi-supervised anomaly detection [26]. Thirdly, security model is a critical enabling factor that should be paid attention to for creating a trustworthy and interoperable IoT system. In this sense, security policies including hardware security, data encryption, secure routing, risk assessment, intrusion detection, anti-malware solution, firewall and trust management are usually considered from the perspectives of perception, transportation and application levels when the practical IoT application is designed [27; 28]. Lastly, key management is of great importance which involves creating,renewing, transferring and accounting for cryptographic items in lightweight, resource constrained IoT devices [29]. Policies and services about generation, renewal, discovery, reporting, escrow, rollover, destruction and revocation for keys and certificates are usually highlighted during the design process [30; 31]. Meanwhile, the research on the IoT integrated solutions has already taken security into account in different layers. A comparison of several surveyed papers is summarized in Table 1. The security challenges in industrial IoT enabled cyber-physical systems was summarized in [12], which highlighted the security in data mining and big data under Cisco IoT framework. A healthcare monitoring framework was designed and implemented in [13], where signal enhancement, watermarking and other related analytics were used to avoid identity theft. Authentication, privacy encryption and secure packet forwarding were studied in [14], and several strategies were proposed under three-layer IoT architecture as well. An overview of security principles, security challenges and proposed countermeasures was presented in [15]. A summary of security issues about protocols and applications for IoT was given in [16], which was based on five-layer IoT framework. A comprehensive list of vulnerabilities and countermeasures on the three layers including edge nodes, communication and edge computing was provided in [17]. To some extent, these studies have achieved the security and privacy goals in one specific layer or multiple layers. However, to the best of our knowledge, there still remain three challenging issues in real IoT solutions. The first one is that low-cost network-connected devices are extremely vulnerable to network attackers due to the limited development costs and device capabilities. The second one is that very few of the existing integrated solutions have considered the security all the way from the device to the cloud. The third one is that the integration of device provision, configuration as well as management can hardly be achieved in a secure and efficient way.