# Secure Watermarking Schemes and Their Approaches in the IoT Technology: An Overview
## 1 Introduction  
As the concept of Internet of Things (IoT) has emerged as a powerful and flexible infrastructure for a wide range of services, which in turn significantly increased the volume of generated data. However, this large volume of data is digitally preserved and accompanied by a number of complications, such as copyright infringement and authentication [1], through data manipulation, copying and redistribution processes [2; 3]. Such data processes are implemented in either a legal or illegal manner, and different approaches are used to hide data such as watermarking, cryptography and steganography [4]. Steganography is the art and science of undetectable communication that is accomplished when hiding information through other available information. Therefore, it is extremely effective in securing the process of access control [5]. Moreover, cryptography is one of the old techniques used in authentication to overcome illegal manipulations of data [1; 6]. Nonetheless, the main risk of such an approach is that data can be decrypted causing an unprotected classified content. To mitigate such issues, the so-called digital watermarking is proposed and is considered one of the focal points of research for many researchers recently [7; 8; 9; 10]. Digital watermarking has also become a significant subject in the field of multimedia signal processing, where it can be defined as an invisible change to a piece of data. Additionally, it can be considered as an enhanced method that can provide protection to the ownership of the digital media against digital piracy [2]. Recently, digital watermarking technology became essential for different fields as it offers various lightweight solutions for several techniques and applications, including cloud computing, electronic health and IoT [11; 12]. Furthermore, confidentiality, integrity and availability are completely supported for sensitive data/information [13]. In the same context, the IoT is widely used in the future, and the IoT security highlights different issues, meantime, the Wireless Senior Network (WSN) approach is considered as a vital spirit and heartbeat infrastructure for several IoT applications and domains [14]. This approach uses a variety of low-cost and low-power internet-connected devices such that these devices sense their surrounding data from different situations and forward them to the Internet [15]. Therefore, energy consumption and security remain the two main challenges in WSNs that need improvement due to their limited resource and outdoor operation. Moreover, sending and broadcasting sensitive information over unsafe network media are still considered to be challenging issues as well [12]. In addition, the traditional security mechanism relying on public key, private key, digital signature, and digital certification in transport layer sockets is not suitable for such types of devices due to the cost of encryption and decryption operations. These challenging issues make techniques such as lightweight security algorithms and watermarking systems a viable choice for these types of devices. Furthermore, these limitations encouraged researchers to study and investigate the domain of various watermarking methods in fields related to IoT [15; 16]. However, different watermarking attacks still need mitigation handling such as rotations, copying and compression [17; 18] that can be available within the acceptable limits. The watermarking method is executed based on three consecutive processes, comprised of generation, embedding, and extraction. These processes are illustrated in Figure 1.  
First, the payload is encoded into a cover object (D) for generating an object that is watermarked. Last, the payload is identified through a decoder. The payload (P\({}_{\mathrm{L}}\)) is considered as a confidential message or information, which is embedded through a cover and the entire information or watermarked image (D\({}_{\mathrm{L}}\)) is forwarded through to a decoder while the payload detection procedure is involved.