## 7 Conclusions and Future Work  
This work proposed, developed, and evaluated a lightweight mutual authentication mechanism with handover function in an edge-fog-cloud environment, specifically focusing on integrating 5G communication technology. This work aimed to address the crucial challenges of securing communication between edge devices, fog nodes, and cloud services while accommodating the dynamic mobility of edge devices within the distributed architecture and leveraging the capabilities of 5G technology. Also, handovers involve switching a device's connection from one access point to another. The authentication process during handovers introduces latency, which can affect real-time applications and services. The proposed mutual authentication mechanism successfully achieved secure and efficient communication within the edge-fog-cloud environment. A mutual authentication protocol that verifies the identities and access permissions of all entities involved in the communication process is designed and developed throughout this work. Using AES cryptography and secure safe handover mechanisms, we were able to make transitions between fog nodes smooth during edge device mobility, ensuring that users could still access services and resources without interruption. Moreover, this work enhanced the security in the edge-fog-cloud environment, mitigating the potential risks of impersonation attacks, eavesdropping, and unauthorized access. The incorporation of robust security protocols into our authentication mechanism provided a shield against potential threats, safeguarding sensitive data and ensuring privacy during communication. The effectiveness and performance of the lightweight mutual authentication mechanism were validated through comprehensive evaluations. A comparative analysis was conducted, contrasting the proposed protocol with existing ones, including TLS 1.3, 5G-AKA, and various handover protocols. The results showcased notable benefits, including reduced computational overhead, minimal communication latency, and seamless compatibility with resource-constrained edge devices. Further advancing the protocols introduced in this work represents a promising and valuable direction for future research. The authentication mechanism can be implemented practically in an edge-fog-cloud environment, and its performance will be thoroughly evaluated. Furthermore, the investigation of energy-efficient authentication strategies for resource-constrained edge devices aims to prolong battery life and improve overall energy efficiency in the edge-fog-cloud environment. Additional security challenges can arise when using different operating systems deployed at the edge, fog, or cloud nodes. Hence, future directions shall study the impact of security within the three-tier architecture while utilizing heterogeneous deployment of operating systems. It worth mentioning that the proposed protocol includes a specific requirement that each participating party must possess eSIM technology. While eSIM offers several advantages such as enhanced security, flexibility, and ease of remote provisioning, it is important to note that the current adoption rate of eSIM technology is not yet universal. This dependency on eSIM technology could be seen as a limitation, as it may restrict the immediate applicability and scalability of the protocol to environments and users who have already integrated eSIM capabilities into their devices. We recognize this as a potential shortcoming and are aware that it could impact the protocol's broader adoption in the near term. **Author Contributions:** Conceptualization, J.Z., A.O. and R.A.-R.; Methodology, J.Z., A.O. and R.A.-R.; Software, J.Z. ; Validation, J.Z., A.O. and R.A.-R.; Formal analysis, J.Z., A.O. and R.A.-R.; Investigation, J.Z., A.O. and R.A.-R.; Resources, J.Z., A.O. and R.A.-R.; Data curation, J.Z. ; Writing--original draft, J.Z. ; Writing--review & editing, J.Z., A.O. and R.A.-R.; Supervision, A.O. and R.A.-R.; Project administration, A.O. ; Funding acquisition, A.O.