TY - JOUR AU - Jagdale,, Balaso AB - Abstract Routing in the Internet of Things (IoT) renders the protection against various network attacks as any attacker intrudes the routing mechanism for establishing the destructive mechanisms against the network, which insists the essentiality of the security protocols in IoT. Thus, the paper proposes a secure protocol based on an optimization algorithm, Monarch-Earthworm Algorithm (Monarch-EWA), which is the modification of the Monarch Butterfly algorithm using the Earthworm Optimization Algorithm (EWA) in order to render effective security to the network. Initially, the effective nodes are selected using the Deep Convolutional Neural Network (deep CNN) classifier based on the factors, trust and energy of the node, and stochastic gradient descent algorithm trains the deep CNN classifier. The secure nodes are involved in routing for which the secure multipath is chosen optimally using the proposed Monarch-EWA, which chooses the secure multipath based on the factors, energy and trust. The analysis of the proposed method in the presence of attacks, such as black hole, message replicate and distributed denial of service, reveals that the proposed method outperformed the existing methods. The proposed Monarch-EWA protocol acquired the maximal energy, throughput and detection rate of 0.2268 J, 48.2759% and 82.6231%, respectively, with the minimal delay of 0.0959 ms. 1. INTRODUCTION The Internet of Things (IoT) possesses several mobile or static objects, and devices are inbuilt with communication, sensors and actuators via the Internet [1, 2]. The transportation and data routing with required security and quality of services (QoS) is the major issue in IoT [2]. IoT uses various technologies, systems and evolving paradigm of devices, based on the Transmission Control Protocol/Internet Protocol, in the physical environments [3, 4]. IoT [5] finds its application in areas, such as building, agriculture and automation in management as well as industrial systems with water grids, smart grids and smart cities. The sensors in IoT are energy-constrained, performing computational and storage operations, and communicate in lossy channels. The basic driving forces in IoT represent the networking and more specifically the routing that formulates the interconnection among the IoT devices. The requirement in IoT routing [6] relies on autonomy, scalability, energy efficiency and secure communication [7, 4]. On the other hand, the unique characteristics belonging to IoT enable the nodes to be subjected to attacks. On the contrary, routing and secure communication attract as research topics in IoT [4]. Moreover, the evolution in IoT improved the implementation steps associated with the smart home networks. With easy-to-operate smart home expansion systems using IoT devices, life has become convenient, comfortable and secure [8]. IoT finds valuable application in health care, urban transportation, vehicle monitoring and space exploration, along with other potential fields [9]. Routing is a significant strategy in a communication stack, and it logically models the network in such a way that the data packets traverse along with the multiple hops between the source and destination nodes. Routing is an NP-hard problem [3], and it gains significance as the nodes in the IoT network perform as hosts and routers during data delivery to the gateways. There are many sensors in the IoT networks, and the data routing from source to destination nodes affects the power consumption of the forwarding nodes. Due to the random behavior of the network, stochastic methods are a natural fit to studying the power consumed by the individual nodes and the entire network. These methods utilize the events that occurred in the past and predicts behavior in the future. Additionally, the routing in IoT is associated with the nodes in discovering the routes with respect to the destinations through beaconing, which finally results in the overhead. At the time of beaconing, there exists flooding of route requests or ping messages of the source nodes that are rebroadcasted until the data packets reach the destination. The destination replies to the requests in order to establish the routes. Moreover, factors like beacon interval affect the transmitting rate and there is a requirement for quantization of the energy, and the performance of the protocol impacts the analysis associated with the overheads in the data packet [10, 11]. Security in IoT is a significant aspect, requiring in-depth analysis as there is a need for a secure network [12]. Trust-based methods in IOT assure secure routing, and reputation is based on the behavior of the node in the past, which is based on the degree of cooperativeness. In case of secure routing, reputation defines the forwarding and routing, and the authentication and encryption mechanisms are used which rendered the transmission of acknowledgments for a transmitted packet. Trust [12] defines the degree of confidence regarding others, and it aggregates all the reputation values held by the entity from another participant. The high reputation values of a node are marked as a trustworthy node, and the legitimate node is based on the trustworthy entity that accomplishes the communication tasks. There are systems based on trust for acquiring secure routing, and the individual system is evaluated for a specific ad hoc application and manages the constrained security threats [13]. Ensuring security in IoT is essential for a trust management mechanism (TMM), which verifies the individual requests of a service based on the security policy. TMM consists of numerous components, like secure routing, authorization and authentication. The TMM design with permitted security is a complex phenomenon [14], and the existing measure based on a rule never copes with unpredictability. The complexity associated with the interdependency in IoT insists the network rise as the key point for facilitating the security policies. The security solutions based on the network suits best for scaling the deployed IoT devices and sheer hardware diversity along with the interoperability constraints [2]. The primary intention of the research is to design and develop a secure routing protocol for IoT by proposing an optimization algorithm. Energy consumption and trust of the nodes are the two parameters considered in developing the secure routing protocol. Based on the energy consumed and the trust, a routing model, termed as Monarch-Earthworm-based secure (Monarch-EWA) routing, is introduced. The overall procedure of the proposed secure protocol includes the following four steps: in the first step, the trust level of a route is measured, and in the second step, deep learning is employed to select the secure nodes. In the third step, route discovery is performed with the route selection step in the fourth step. Initially, the energy level of the nodes is computed, followed by the computation of trust using various trust factors, like direct trust and indirect trust [15, 16], together with a new trust factor, named active trust, which is formulated newly based on a certain behavior of the nodes. Then, the deep learner is applied for selecting the secure nodes. Once these secure nodes are chosen, the route selection and route discovery are performed using the proposed Monarch-EWA algorithm. The proposed algorithm is developed by combining Monarch Butterfly Optimization (MBO) [17] with Earthworm Optimization Algorithm (EWA) [18]. The major contribution of this paper is the development of the Monarch-EWA, which is developed by integrating the MBO and EWA. The proposed Monarch-EWA selects the multipath from the total discovered paths, for secure routing. The paper is structured as follows: the background of routing protocols is discussed in Section 1, and Section 2 deliberates the review of the existing methods. The proposed method of performing secure routing is discussed in Section 3, and Section 4 gives the results of the method. Finally, Section 5 concludes the paper. 2. MOTIVATION This section deals with the existing routing protocols and the challenges of the research, which stood as the motivation for proposing a new secure protocol. 2.1. Literature survey This section reviews eight existing methods in the literature: Mick et al. [19] developed Lightweight Authentication and Secured Routing (LASeR) in which scalability was attained using a hierarchical design with minimal computational burden. The drawback of the method was about the inapplicability of the method for live testbed deployment on real devices. Hatzivasilis et al. [13] modeled a method, the Self-Channel Observation Trust and Reputation System (SCOTRES), which rendered higher degree of security, but the method failed in the presence of the jamming attackers, and no communication was accomplished, affecting the path between source and destination nodes. Shin et al. [8] modeled a lightweight and secure session key approach that assures the security of the network, and the performance was better with greater transmission rates and throughput. The drawback of the method was regarding the lack of consideration of the 5G distributed mobility management, and the performance evaluation lacked in terms of the mobility models and traffic. Airehrour et al. [4] used a time-based trust-aware RPL routing protocol (SecTrust-RPL) that acquired the optimal routing decisions even in the presence of malicious nodes, rendering an optimal throughput. The drawback of the method was that the method failed to consider secure routing since the battery of the nodes depleted and led to selfish behavior. Ai et al. [9] modeled a smart, collaborative routing protocol, Geographic energy aware routing and Inspecting Node (GIN), which minimized the network delay and reduced the packet-loss delay, thereby increasing the throughput. The failure of the method was regarding the inapplicability of the method in the information collection phenomenon. Kalkan and Zeadally [20] used a role-based security controller architecture that addressed the scalability and heterogeneity issues and rendered a network with a highly dynamic environment. However, the method suffered from security issues. Dhumane and Prasad [2] modeled a multiobjective fractional gravitational search algorithm that improves the lifetime of the network while taking into account the number of alive nodes and energy of the network. The failure of the method was about enhancing the performance by fixing the objectives of the model. Reddy and Babu [21] developed a method based on Optimal Secured Energy Aware Protocol (OSEAP) and Improved Bacterial Foraging Optimization (IBFO) algorithm which rendered a better performance with minimal energy consumption, higher throughput and delay, whereas the lifetime of the network was affected. 2.2. Challenges The challenges of the research are listed below. ▪ The significant challenge is regarding the dynamic nature of the data flow in IoT. The total users and volume of the data flow in IoT change with respect to time. However, the existing techniques for controlling the data flow assume itself as a stable network. Thus, these existing techniques did not take into account the security of the network. Whenever huge data streams reach at the same time, the whole IoT is paralyzed [22]. ▪ The significant challenges regarding the security in IoT are about their scalability and heterogeneity. In contrast to the traditional devices to assure adequate processing, computing and storage resources, IoT sensors and other mobile devices are fully resource-constrained [20]. ▪ A time-based trust-aware RPL routing protocol [4], named SecTrust-RPL, follows the mechanism based on trust. Even though the performance of the protocol was better compared with the standard RPL protocol, in case of detecting the Rank and Sybil attacks, SecTrust-RPL failed to address the colluding attacks, such as Rank/Sybil, Rank/Blackhole and Rank/Selective Forwarding attacks. ▪ Extensive devices linked to IoT suffer from challenges like large consumption of battery power, modeling of devices such as smart e-health and development of a control system for smart homes [23]. ▪ The network lifetime, failure in the battery of the IoT devices and usage of the sensor networks are the significant challenges prevailing in the existing literary works [23]. 3. PROPOSED SECURE ROUTING IN IOT BASED ON THE OPTIMAL ROUTE SELECTION Secure route selection in IoT is effective in enabling optimal communication over secure routes, which is the ultimate aim of the research. The paper discusses secure route selection based on the optimization, and Monarch-EWA chooses the multipath to progress the communication. Initially, the nodes in IoT are subjected to the calculation of trust and energy which forms the input to the secure node selection module, which is progressed using the deep CNN classifier. The input to the deep CNN classifier is the direct trust, indirect trust, active trust and energy, which are assessed for all the nodes of the network, and the secure nodes are finalized. The deep CNN classifier utilizes the SGD algorithm to tune the optimal weights, and the secure nodes are involved in the secure routing process. Using the secure nodes, the paths are discovered which are performed through fixing a source, and the destination nodes and the optimal paths are chosen based on the proposed Monarch-EWA, which is fitness-constrained. Figure 1 shows the schematic diagram of the secure routing in IoT. Consider an IoT network with |$m$| number of nodes, and let us represent the |${l}^{\mathrm{th}}$| node as |${N}_l$|⁠; |$(1\le l\le m)$|⁠. The trust and energy of the |$m$| nodes are computed, and the secure nodes are chosen based on the deep CNN, and the total secure nodes are given as |$s$|⁠, such that |$s