Research On Multi-Party Quantum Private Query

The security of traditional cryptography relies heavily on the mathematical hard problem,which is difficult to be solved in the classical world.With the advent of quantum computers,the security of traditional cryptography is in jeopardy,and quantum cryptography was created to solve this problem.Quantum cryptography relies on the fundamental properties of quantum mechanics,making it theoretically capable of achieving unconditional security.In view of this,scholars have proposed many protocols in the field of quantum cryptography,and quantum cryptography has become an important branch of quantum information.Quantum private query is an important research element in quantum cryptography and an extension of classical private query in the quantum domain.Although scholars have proposed many quantum private query protocols based on quantum key distribution,most of them consider single-bit data and single-user queries in databases.In order to improve the practicality and query efficiency of existing protocols,this thesis first proposes a single-user quantum private block query protocol based on D-dimensional Bell states,followed by a multi-user quantum private block query protocol based on Ddimensional single-photon product states.The main research of this thesis is as follows.1.For the current quantum privacy query mostly obtains single-bit key,this paper proposes a quantum privacy block query protocol based on D-dimensional Bell state,which can achieve key distribution by preparing D-dimensional Bell state through a thirdparty quantum server,and can obtain a block key by executing the query protocol once,instead of executing the protocol multiple times,which improves the query efficiency of the protocol.This protocol prepares the D-dimensional Bell state for security detection,in this detection process,the user side and the database side each obtain a particle in the Ddimensional Bell state,and the security detection passes when the measurement results of the user side and the database side are the same,if the results are different and the error rate exceeds a specified threshold,it indicates the existence of an eavesdropper in the quantum channel.The security analysis shows that this protocol can resist common quantum attacks such as the middleman attack and the entanglement measurement attack.The protocol comparison analysis shows that this protocol has some advantages in terms of particle count,quantum capability requirements,data storage type,and security detection.2.In response to the fact that most current protocols consider only single-user private queries,this thesis proposes a multi-user quantum private block query protocol based on D-dimensional single-photon product states.This protocol uses semi-quantum technology,where the user side and the database side only need the ability to access the quantum channel and perform quantum rearrangement to reduce their quantum cost.In order to allow multiple users to access the information of data blocks at different locations in the database,this protocol needs to be executed only once.To improve the efficiency of users querying data,this protocol uses Grover algorithm to search for multiple private blocks in parallel.The security shows that this protocol is resistant to both external and internal quantum attacks and finally,simulation experiments are performed for Grover in this protocol.