## 3 The Proposed 3-Tier-AKA Model
### Authentication within the Edge-Fog-Cloud Environment  
Within the edge-fog-cloud 3-tier environment, various communication scenarios occur, involving direct communication between edge devices and fog nodes and the interactions between fog nodes themselves and between fog nodes and the cloud. These communication channels must be secured to protect sensitive data and maintain the system's integrity [7]. Authentication plays a crucial role in the edge-fog-cloud computing environment due to several key needs and challenges:  
* Data security: Data are processed and stored across various tiers, from edge devices to fog nodes and cloud servers. Authentication ensures that only authorized entities can access and manipulate sensitive data, reducing the risk of unauthorized data breaches or leaks [51].
* Resource access control: Different architecture tiers have varying levels of resources and capabilities. Authentication helps control access to these resources based on user roles, permissions, and the specific needs of applications, ensuring optimal resource utilization [51].
* Seamless handovers: Devices moving between different tiers, such as from edge to fog or fog to cloud, require smooth handovers without interrupting services. Authentication enables seamless handovers by ensuring the device is authenticated in the environment before communication [52].
* Dynamic mobility: Devices in this environment can be mobile, moving across different fog nodes. Authentication mechanisms are needed to handle dynamic mobility patterns without disrupting services [53].
* Latency and real-time requirements: Applications in fog-edge environments have stringent latency requirements. Authentication mechanisms must be fast and efficient to avoid introducing unacceptable delays [54].
* Adversarial threats: Distributed systems are susceptible to various threats, including man-in-the-middle attacks and impersonation. Authentication mechanisms need to counteract these threats effectively [51].
* Authentication overhead: Introducing authentication processes can lead to communication overhead. Balancing the need for security with the performance impact of authentication is a challenge [43].  
This work proposes a mutual authentication protocol. It ensures that the communicating entities (edge devices, fog nodes, and the cloud) authenticate each other's identities before initiating any data exchange. Given the mobility of edge devices, a mutual security protocol is designed for the handover process. When an edge device transitions to a new fog node, it must undergo mutual identity verification to establish a secure connection. This verification step ensures that the edge device and the new fog node mutually authenticate each other's identities before enabling communication.  
The proposed implementation of a mutual identity verification protocol for handover in the edge-fog-cloud 3-tier environment reinforces the security measures. It addresses the challenges posed by mobile edge devices. Note that by verifying the identities of both parties involved, the protocol guarantees that only authorized edge devices can connect to new fog nodes, reducing the risk of unauthorized access and potential security vulnerabilities. For example, in a smart grid environment, edge devices monitor and control the distribution of electricity in real time. Data integrity and encryption are critical to protecting against cyber-attacks that could disrupt the power supply.  
In addition, the 3-Tier AKA protocol suite enables seamless and secure communication, ensuring uninterrupted access to services and resources during the handover process. This enhances the environment's overall reliability, efficiency, and integrity, simplifying the process of moving between fog nodes without causing interruptions or disruptions.