## 4 Steps and Analysis of Cloud-Edge Collaborative Intelligent Security Encryption Strategy
### Strategy  
The use of traditional single encryption techniques does not take into account the cost and security issues that may arise when the volume of data is large, and the security assessment of the transmission task is carried out at the time of each data transmission, with high-security encryption being used for high-security tasks, and low-security encryption for low-security tasks, and the security assessment strategy is carried out in the following ways:  
1. Strategy based on historical experience: based on the information that has been evaluated historically, its data value is categorized, and at each new task, the priority is to go through the existing data attributes to be evaluated. The following rules can be used when there are no matching data attributes: 1. Adoption has maximum matching. Assume that the matching strategies are \(A_{1},A_{2},\dots,A_{n}\), the attributes of each class are \(H(A)\), and the attributes of this transmission data matching each strategy are \(M(A)\), then the strategy \(A_{i}\) that maximizes the value of \(\frac{H(A)}{M(A)}\) is selected, and the matching rate is set to be greater than a certain threshold. 2. If none of the strategies satisfy in the previous strategies, a default strategy approach is given using customized data values.
2. Learning-based strategy: a hierarchical strategy function is formed by giving samples and examples, and machine learning and neural networks are used to extract features and mine the attributes of the data, which leads to a strategy that matches the value of the specific data.  
The previous strategy determines that \(f(m_{i})\); in order to facilitate the calculation, we only focus on the encryption rounds when considering the security level, without considering the weighting problem and ignoring the influence brought by the key update cycle, using \(B\) for gain and \(D\) for loss, then the previous benefit formula can be expressed as  
\[BF=B-D=f_{1}(Em)-f_{2}(M_{i})-\sum_{i=1}^{10}N_{i}\cdot e^{t} \tag{7}\]  
For a task with a constant security level, we only need to make the benefit function (\(BF\)) slightly greater than 0; because \(f_{1}(Em)\) does not keep increasing, it receives a constraint from cost, so we can use a suitable security policy to categorize the transmission of different security tasks to ensure security while saving cost. For the RC5 encryption method, it has three variable parameters: group size, key size, and number of encryption rounds. It is characterized by high flexibility, fast encryption speed, and high security. We fix the group size to 128 bits. The steps are as follows to calculate the encryption rounds.  
The following steps should be referred to when selecting the security key to be used according to the security level of the task:  
1. Select a suitable security evaluation strategy, and then output its security level and calculate the security value \(Mi\).
2. Calculate \(f_{1}(Ks)-f_{2}(M_{i})-\sum_{i=1}^{10}N_{i}\cdot e^{t}=0\), and the calculated \(Ks\) will be chosen as the appropriate number of encryption bits for the encryption method for this task.  
Send the situation of this task to the key management center, encrypt the data using the corresponding key to get the ciphertext c, and then start sending.  
For the three different security level tasks in the previous algorithm design, key grading technology is used to categorize different security tasks, reduce costs, and increase security.In the actual industrial production, there will be m encryption levels and n levels of security tasks. The use of the previous algorithms can greatly reduce the cost of data transmission, reduce the pressure on the host computer, and, at the same time, protect security. The algorithm process is shown in Figure 6.