## 4 Steps and Analysis of Cloud-Edge Collaborative Intelligent Security Encryption Strategy
### Credibility Model
#### 4.2.2 Introduction to Credibility Model  
Cyclical supervision of a service-providing enterprise through a third-party government trusted unit comprises reviewing the national product quality qualification standard \(S=(S_{1},S_{2},\dots,S_{m})\), and standardizing the quality of the services provided around the previous rules. The credible value is used to measure the integrity of the enterprise's breach of contract and whether the product quality meets the standards required by the downstream enterprise. Specific credible value calculation can be comprehensively considered from n perspectives in this paper, from the product quality situation and time delivery situation to the calculation. \(P_{e}\) is the number of qualified products, and \(P_{a}\) is the number of all products. The product quality situation can be calculated by the following Formula (2):  
\[Q=\frac{P_{e}}{P_{a}} \tag{2}\]  
Regarding the time delivery situation, certain companies may prefer that the upstream companies supplying their products deliver as early as possible so that they have sufficient time to prepare their production capacity, so it is calculated based on 80% (this is denoted by \(w\) in (3)) of the delivery time of the contract, with earlier than that being preferred, and later than that starting to decrease. \(T_{f}\) is the completion time of the actual task, \(T_{s}\) is the start time of the task, and \(T_{e}\) is the deadline of the task. This is calculated using the following Formula (3):  
\[S=\begin{cases}1,&\frac{T_{f}-T_{s}}{T_{e}-T_{s}}\leq w\\ w\cdot\sqrt{\frac{T_{f}-T_{s}}{T_{e}-T_{s}}},&\frac{T_{f}-T_{s}}{T_{e}-T_{s}}> w\end{cases} \tag{3}\]  
By using Formula (3), the direct trust level \(T_{ij}\) calculated by node \(i\) and node \(j\) based on the direct interaction behavior information during the time period is  
\[T_{ij}=\sqrt{Q_{ij}\cdot S_{ij}} \tag{4}\]  
where \(n\), \(W_{ij}\) is the set of nodes that have a cooperative relationship with node \(i\) and their weights; the weights are generally averaged, and when some business interactions are more important, the weights can also be distributed unevenly. Weighting the feedback information of node \(i\) with all the other cooperating nodes of node \(i\) during the time period gives the direct credibility of node \(i\)\(T_{i}\):  
\[T_{i}=\sum_{j=1}^{n}\sqrt{Q_{ij}\cdot S_{ij}}\cdot W_{ij} \tag{5}\]  
Considering that the historical information of node \(i\) has some degree of information reflecting the business status of the enterprise, the historical credible value can occupy a part of the weights, and then the integrated credible value calculated with the direct credible value can reflect the enterprise integrity and collaboration:  
Figure 5: Industrial relationship map.  
\[T_{new}=w\cdot\sum_{j=1}^{n}\sqrt{Q_{ij}\cdot S_{ij}}\cdot W_{ij}+(1-w)*T_{old} \tag{6}\]  
From (6), it is evident that the credibility of an enterprise fluctuates with its level of collaboration. A higher credibility value suggests that the enterprise's products adhere more closely to national standards. Engaging with third-party government-certified entities for supervision can effectively identify untrustworthy enterprises, mitigating losses and preventing credible enterprises from collaborating.