# Quantum Privacy Query Protocol Based on GHZ-like States
## 5 Conclusions  
We propose a quantum privacy query protocol based on the GHZ-like states, which solves the following problems. The role of our scheme is to perform medically assisted diagnosis. [PERSON] encrypts the information when he sends it to [PERSON]. [PERSON] uses the obtained key to decrypt the required information. This scheme enables the patient to acquire detailed information about the prediction of disease progression and the development of a treatment plan. In this paper, we propose a quantum privacy query protocol based on GHZ-like states. Compared with the existing QPQ protocols, this protocol has the following differences: first, in our security analysis, we do not consider the joint measurement attack because [PERSON] can precisely control the number of keys obtained by [PERSON] without post-processing. In Step 3, we add the detection of the decoy factor. The consistency of detection results can help our protocol ascertain whether there is a third-party attack or not. In Step 7, we add authentication. After both the communicating parties have obtained the key, the role of authentication is to prevent unauthorized users or devices from participating in the communication. These are used to enhance the security of the protocol. Moreover, the database and the user's privacy can be sufficiently protected. The performance of our protocol is greatly improved. Then, GHZ, as the largest entangled state, will increase the efficiency and reliability of the quantum information processing process, and it is easy to fabricate and realize. GHZ-like states are easier to fabricate than GHZ states and consume fewer quantum gates. In the actual process of quantum privacy query, the quantum state may be affected by certain noises and interferences, and the GHZ-like states can still maintain its entanglement properties in such an environment. There are still many improvements in the study of quantum privacy queries in this paper, and we need to design a more practical QPQ protocol in combination with practical scenarios.  
At the same time, we also need to improve the following questions in the subsequent research. This study can only realize the query of the same data address by multiple users, so how to realize that separate users can retrieve different data addresses at the same time is of great research significance. Based on our single-quantum privacy query, we can go on to explore the entanglement properties of the four-particle GHZ-like states to apply into the multi-user quantum privacy query. Then, our protocol can only retrieve one data address, and in reality, the data are stored in blocks. We need to improve the protocol to make the user retrieve more data information at one time under the security situation. More data information can be obtained. Finally, there is still some improvement in the communication efficiency of our protocol. Future research in quantum privacy querying should improve security while also improving the efficiency of the program to make it better. Of course, we also hope to achieve higher breakthroughs in the subsequent areas.  
This article was prepared through the collective efforts of all the authors. Conceptualization, B.L. and T.L.; methodology, B.L. and T.L.; validation, B.L., T.L. and J.Z.; formal analysis, J.Z.; investigation, J.Z.; resources, B.L.; data curation, J.Z.; writing--original draft preparation, T.L.; writing--review and editing, B.L.; visualization, J.Z.; supervision, B.L.; project administration, B.L. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China (62002105) and The Key Research and Development Program of Hubei (2021 BEA163).  
The authors confirm that the data supporting the findings of this study are available within the article.  
The authors declare no conflict of interest.