Research On Protocols Of Quantum Private Database Queries:Design And Analysis

Quantum cryptography is the combination of cryptography and quantum mechanics. The safety of quantum cryptography is guaranteed by the basic principles of quantum mechanics, which has nothing to do with the computing capabilities of the attacker. Compared to classical cryptography assumption, which is based on computational complexity, quantum cryptography has a unique advantage in essence, so it has becoming the important branch of the new cryptography technology. Quantum cryptographic is used in key-distributing, and it also has a very good performance in the field of private queries.The main contents of this thesis deals with theoretical aspects of quantum private database queries, and we proposed a novel private database query protocol based on counterfactual quantum key distribution protocol, and we discussed the security and the performance of our proposal. In addition, we studied the private queries with a third party and we have given a feasible solution.In the protocol based on the counterfactual quantum key distribution, we used the main scheme of the system of key-distributing proposed by Noh, and we changed the process of the classical communication. Furthermore, we introduced some detection strategies to ensure that the asymmetric key can be generated securely. Our proposal has good flexibility and extensibility, and the communicators can adjust the related parameters according to their needs, and make the trade-off between the safety and the efficiency. It is proved that private database query protocols cannot be unconditionally secure, so we do the research on the private database query protocol with a third party, and we have given a feasible solution. There is a third party to help the user and the database owner to complete the database query, so the privacy of the user and the database owner is can be ensured. At the same time, the third party cannot receive any information about the database or user’s query.