The Research Of Quantum Private Query Protocol Over Noise Channels

Quantum private query is an extension of classical symmetrically private information retrieval in the quantum field.Compared with mathematical problem based classical symmetrically private information retrieval,quantum private query has obvious advantages in terms of communication complexity and security.These advantages stem from the special nature of quantum mechanics(i.e.quantum property of entanglement,Heisenberg uncertainty principle,etc.).Insuring database security and user privacy are two basic requirements of quantum private query protocol.While satisfying the security requirements,the problem of the classical client and quantum channel noise are also two important factors to determine the practicability of quantum private query protocol.This thesis focuses on how to apply a private query protocol to classical clients and tolerate the problem of quantum channel noise on the premise of security restriction.Firstly,this thesis designed a quantum private query protocol with classical clients.This protocol uses single photon as the resource state of quantum private query and two almost “classical” clients(database owner and data user)can share an asymmetric quantum key with the help of a cloud server who has the full quantum capability.The specific advantages of this protocol are listed as follows:(1)The complex quantum operations are outsourced to the quantum server without leaking client's privacy,in which database owner and data user only need to access the quantum channel and reorder the qubits;(2)Because of possessing the ability of real-time security check,therefore,it can obtain higher security;(3)Even if the quantum server is assumed to be a powerfully untrusted adversary,all possible attacks of quantum server can be real-time detected by the security check.Subsequently,this thesis has extended the above-mentioned protocol and designed a quantum private query protocol which can immune collective-noise.This protocol has the following advantages:(1)Private communication can resist noise interference by using logical Bell state as the quantum resource;(2)This protocol uses the entanglement principle of quantum state and Heisenberg uncertainty principle to protect the database security and users' privacy.(3)Achieving quantum private query for classic clients in noise environments.To sum up,this thesis has successfully solved the exiting problem of channel noise and insufficient quantum ability in the practical application of quantum private query by using the method of securely delegated computation.The safety analysis shows that the above-mentioned two protocols not only can resist the external attacks,but also can against the stronger internal attacks.