## 5 System Design
### Strategic Game Model  
The incorporation of this strategic game model (SGM) optimises the selection process of CIN. The proposed SGM uses both public and private cloud ecosystems to select legitimate nodes cost-effectively and reliably. For any given adjacent nodes, each node in a distributed ad hoc environment of IoT is required to define its CIN and RIN along with its explicit roles. In contrast to all possible adjacent nodes, a specific \(i\)th node is needed to announce itself as a CIN, based on quality metric \(QM\) and global trust \(GT\) attributes. For this purpose, a set of adjacent nodes \(A(i)\) is considered by the \(i\)th mobile node with an input of \(QM\) and \(GT\). A matrix is constructed for adjacent nodes consisting of \(GT\), \(QM\), and their respective identity information. An \(i\)th node announces itself as a CIN if its \(QM\) score is found to be more than a cut-off value of the same as its adjacent nodes. A similar selection operation is carried out for a higher value of \(GT\) if both are found to be less than the cut-off, then the \(i\)th node announces itself as a RIN. All RIN must compare their features with respect to \(QM\) and \(GT\) to make them deployable for RINs. Using this operation, a definite payoff is allocated to the RIN when it plays the role of CIN. This is one of the essential processes from a security and privacy perspective, as misbehaved nodes will never be able to announce themselves owing to the discrepancies in their \(QM\) and \(GT\) scores. The empirical expression used for representing the degree of fluctuation between the CIN and RIN, i.e., \(QM_{RIN-CIN}\) perspective, is as shown in Equation (2):  
\[QM_{RIN-CIN}=(1-\Delta QM)\times 100 \tag{2}\]  
Figure 4: Core structures, dependent entities, and function of CSC. Figure 3: Dependent entities and function of GTC. Equation (2) shows that the variable \(\Delta QM\) represents the ratio of \(QM\) for RIN to \(QM\) for CIN. A similar mathematical strategy, shown in Equation (3), is applied for the expression fluctuation of \(GT\) for CIN and RIN as follows:  
\[GT_{RIN-CIN}=(1-\Delta GT)\times 100 \tag{3}\]  
As shown in Equation (3), the variable \(\Delta GT\) represents the ratio of \(GT\) for RIN to \(QM\) for CIN. The above two expressions are used to overcome the possible evolution of fluctuation and hence assist in normalising it. It should be noted that selection of CIN is carried out if an \(i\)th node consists of higher values than either of the above expressions in the least case or both expressions in the best case. The search and selection of the feasible CIN among the adjacent nodes in IoT are carried out by the \(i\)th node that announces itself as RIN. The RIN allocates an optimal payoff to the selected CIN based on their services. The value of the payoff to be assigned to the CIN is entirely equivalent to the legitimacy of the CIN, based on the \(QM\) and \(GT\) scores stated in both Equations (2) and (3). The mathematical computation of the payoff for the RIN is expressed as in Equation (4). \[P_{RIN-CIN}=mean(QM_{RIN-CIN},\ GT_{RIN-CIN}) \tag{4}\]  
There is also a possibility that the value of the payoff is to witness multiple acceptances by multiple numbers of RIN within the communication range of CIN. In such conditions, the RIN is required to compute the gain, G, for selecting the CIN, which is mathematically expressed as in Equation (5),  
\[G_{RIN-CIN}=[\theta(P_{RIN-CIN}).\ QM]-P_{RIN-CIN} \tag{5}\]  
Equation (5) shows that the first component \(\theta(P_{RIN-CIN})\) is equivalent to the individual payoff \(P_{RIN-CIN}\) divided by the total value of the payoffs \(P_{RIN-CIN}\) for all the adjacent nodes. The second component, \(QM\), is the summation of \(\Delta QM\) and \(\Delta GT\) obtained from Equations (2) and (3). The actor, RIN, is the one that initiates the game by exploring the feasibility of CIN in the vicinity of their communication range, i.e., CIN(RIN). At the same time, it uses a private cloud to do so using its on-demand routing scheme for propagation.