## 5 Application and Analysis
### Performance Analysis of Access Control Policy Conflict Resolution  
In the process of access control policy synthesis, the more attributes and authorization items there are in the access control policies, the more complex the synthesis becomes, and the higher the probability of conflicts arising. Therefore, it is common to analyze the synthesis under a fixed number of attributes. When the number of attributes is the same, it indicates that the complexity of the access control policies is similar. Under this condition, the number of conflicts in access control policies will increase with the increase in the number of policies. In other words, the number of conflicts is directly proportional to the number of access control policies. The most important aspect of access control policy synthesis is resolving conflicts through policy synthesis operators and priority principles.  
Here, we assume the number of policies involved in access control policy synthesis ranges from 100 to 1000. According to the principles of access control policy resolution, conflicts in access control policies are primarily resolved through the owner attributes of the policies, specific policy priorities, and model priority principles. Ultimately, the synthesis of the participating access control policies becomes the resolution within the same access control model.  
As for the time performance shown in Figure 6(a), during the process of resolving access control policy conflicts, access control policies based on trust attributes can first filter the policy set for the accessed resources based on the trust level and the sensitivity. This filtering reduces the number of policies involved and improves the efficiency of conflict detection. However, in the process of synthesizing access control policies, the impact of changing attributes on conflict resolution should be considered. The worst case is when the trust level of the subject suddenly decreases after conflict resolution, requiring the resynthesis of access control policies to protect the security of resources. The best case is when the trust level attribute of the subject last updated before access control policy synthesis, and remains unchanged throughout the access process, reducing the number of policy synthesis instances. Although the worst case requires more time, it ensures the security of resources and improves the overall security of the system, making the expenditure of time worthwhile. Since the computation and update time for trust level values is short, it can be ignored.  
As for the accuracy performance shown in Figure 6(b), previous research has shown that the optimal conflict resolution rate for various models is generally around 80% [21], while the resolution based on joint priority principles has a significant increase to 85%. In addition, before applying the optimal algorithm for access control policy synthesis in each model, the number of access control policies should be reduced to at least one-third of the original number, when the number of access control policies is reduced within the same model through owner priority and specific policy priority. Therefore, it can be concluded that the conflict resolution algorithm based on joint priority principles has already reduced the number of policies involved in access control policy synthesis during the initial screening phase. Therefore, the conflict resolution algorithm based on joint priority principles proposed in this paper for access control policy synthesis is more efficient and secure.