# Security Issues in IoT-Based Wireless Sensor Networks: Classifications and Solutions
## 2 Backgrounds and Security Problems  
### WSN-IoT Context  
WSNs are an emerging technology and are being deployed in many different fields of application. These sensor nodes are deployed in an area to self-organize into a wireless network to collect and to aggregate data about the environment [3; 25]. A typical WSN consists of a large number of small-sized, low-cost, densely deployed sensing nodes that communicate wirelessly [8]. The networks have certain limitations due to the nature of such networks. They pose special challenges because of the resource limitations of each sensor node, especially in terms of memory and computing power [26]. Fundamental power constraints eventually lead to innovative design problems due to computational and storage limitations [27]. Realistic implementations show that sensor nodes are usually deployed in environments where they are highly vulnerable to physical damage [8] and where it is difficult to replace batteries or to maintain them. This affects the network topology due to damaged or compromised nodes. Furthermore, unreliable communications in unmonitored environments make the direct use of existing security methods on sensor platforms difficult due to the complexity of algorithms. These challenges are the foundation for further research on security in WSNs, especially while integrating the IoT [3]. Due to these unique challenges, traditional security techniques are insufficient to meet the security goals of confidentiality, integrity, reliability, and availability. The IoT is considered a global network system where billions of connected devices can communicate with each other via the Internet without human interaction [28]. In particular, IoT networks can be deployed based on WSNs to provide numerous services and applications such as smart homes, battlefield monitoring systems, smart healthcare systems, and smart transportation for smart cities [29; 30]. As shown in Figure 2, a WSN-based IoT application deployment scenario includes three layers: the network layer, cloud/fog layer, and application layer. Figure 2: WSN-based IoT application deployment scenarios for smart cities. The highest layer of IoT is the application layer, including several applications such as smart agriculture, smart home, etc. Remote users can receive warning information through the Internet connected to computers and can make decisions based on the information collected. The cloud/fog computing layer is responsible for aggregating and processing enormous amounts of data accurately to reduce the computational burden on the upper layer as well as avoid network congestion. The procedures can be performed by smart IoT devices such as routers, base stations, or servers equipped with strong processing capabilities, large memory, and unlimited power [31]. The network layer is where sensor devices can be deployed in real environments to measure the parameters of diverse physical phenomena (temperature, humidity, air pressure, precipitation, etc.) connected to WSNs [32]. Security in WSNs and the IoT is important and necessary for many specific cases and reasons, including protecting personal information, ensuring data integrity, and preventing negative consequences of attacks. In addition, security is also a factor that enhances the reliability and performance of the entire system. This work aims to focus on the security issues that arise when combining WSNs and the IoT. The current challenge is to address the security of WSN-IoT from a general perspective and not as a limited set of issues related to separate technologies. WSNs play a vital role in collecting information about the environment, while integrating with IoTs leads to different security requirements that might arise during the combination process as follows. 1. WSN-IoT devices need strong authentication mechanisms to ensure that only authorized users and devices can access the network and data. At the same time, data transmitted between devices and systems must be encrypted to prevent unauthorized access and protect against interpretation. 2.