## 4 the Proposed Secure Multicast Routing Protocol: DLSMR
### The Proposed Deep Learning-Based Secure Multicast Routing Protocol: DLSMR  
We describe the proposed DLSMR protocol to establish a high-stability multicast tree and improve security performance as shown in Figure 4. The objective function of this approach is to predict the secure and unsecured nodes during the routing process. Due to the node's mobility changing rapidly in FANETs, it makes it easy to attack the network. In particular, wormhole attacks pose a high risk when the nodes can manipulate packets during routing and data transmission. Furthermore, also, even when we consider unicast transmission, it makes the control overhead very high. Thus, this paper proposes deep learning-based secure multicast routing to avoid wormhole attacks and improve control overhead in FANETs. It differs from previous works for solving wormhole attacks using bio-inspired, position-based, and distance methods. In this approach, we consider deep learning to predict the secure and unsecured nodes quickly during the routing process. The use of this process can mitigate these threats, ensuring reliable and secure communication between nodes. Additionally, multicast routing protocols can accommodate this dynamic nature by allowing for frequent group membership changes and route updates. As can be observed in Figure 4, a source node (S) needs to establish a multicast tree to the multiple destination nodes (D). After the clustering process is completed, each D that wants to receive data transmission sends a join request to the CH in the cluster. Then, S sends a MRREQ packet to each CH by unicast to find the multiple destination nodes. After that, CH will broadcast the MRREQ packet to each CH to find the multiple destination nodes. When UGW receives the MRREQ packet, it updates its routing table and re-broadcasts the MRREQ packet to the neighbor nodes. When a CH who has a multicast group ID receives an MRREQ packet, it updates the routing table and replies a RREP packet to the previous node by unicast. We design the DL framework with the node ID, node position, destination ID, destination sequence, hop count, and remaining energy as input parameters, and secure and unsecured node ID, secure and unsecured status as output parameters. By using a DL framework, we can determine whether the next node is secure or not to establish a secure multicast route from S to multiple destinations as detailed in Section 4.4. Figure 5 illustrates the flowchart of the proposed secure multicast routing protocol, which can be summarized as follows:  
**Route Request Process:**  
* **Step 1: Initialization** After the clustering process is completed, each destination node (multicast member node) in a cluster that wants to receive certain data sends a join request (JREQ) to its cluster head by unicast. The JREQ contains the following: \[\langle\text{Type},\mathsf{S}_{\text{ID}}^{\text{JREQ}},\mathsf{D}_{\text{ID}},\mathsf{Status}\rangle\] where \(\text{Type}\) denotes packet type, \(\mathsf{S}_{\text{ID}}^{\text{JREQ}}\) identifies the node that wants to join a multicast group, \(\mathsf{D}_{\text{ID}}\) denotes the node ID that wishes to join, and \(\mathsf{Status}\) denotes the status of the node (join, leave, etc.). Next, the cluster head stores the multicast ID (\(\mathsf{M}_{\text{ID}}\)) associated with this request in its own table; go to **step 2**. * **Step 2: Source Node Operation for Route Request: Generates and Sends Route Request Packet** A node that wants to send data to the multicast group becomes the S. S initiates the process by generating a MRREQ packet and unicasts this MRREQ to its CH.