The Study On Key Problems Of Secure Multi-party Quantum Computation

Quantum information science is a new interdiscipline of quantum mechanics,computer science and information science.With the development of disciplines and further research,remarkable achievements have been made in this area,while threats have been posed to classical information security.Classical cryptography based on the computational complexity is particularly fragile when facing powerful quantum computing and quantum algorithms.Fortunately,the development of quantum information science also provides new thoughts and avenues for information security.Based on basic principles of quantum mechanics,a more secure quantum cryptography system will be constructed by integrating quantum information technology into classic cryptography.Consequently,secure computing and communication in the complex environment will be ensured.The unique safety features of quantum cryptography have aroused many scholars' concern and become the research hotspot of quantum information science.Secure multi-party quantum computation is not only an important subfield,but the extension and expansion of quantum cryptography.It mainly focuses on how to safely accomplish a computing task or a function in a general environment.It plays a significant role in some security applications such as secret sharing,electronic voting and multi-party function computation.This dissertation explores the basic protocols and application protocols of secure multi-party quantum computation,and mainly researches on quantum secret sharing,secure preparation of quantum state and blind quantum computation.In particular,much work has been done on construction,security and applicability of the protocols and the results achieved are as follows:(1)We present a simple and effective multi-party quantum secret sharing protocol based on GHZ states and properties of mutually unbiased bases.Without any unitary operations the participants can implement secret sharing only by projective measurement and communication.Theoretical analysis of this protocol not only has high security against conventional attacks such as intercept-resend attack and entanglement-and-measurement attack,but also shows great capabilities of information detection and protection in dangerous false-information-injection attacks.Most quantum secret sharing protocols make limitations or assumptions on the behavior of participants without considering the fact that participants might make false information injection attacks.Moreover,the protocol can be extended to high-dimensional quantum systems with the same security by applying high-dimensional GHZ states.(2)We propose a scheme for joint remote preparation of four-qubit cluster-type state,in which a special orthogonal measurement base is constructed by using the EPR pair as quantum channel.The senders perform projective measurement on EPR particles;meanwhile the receiver performs relevant appropriate unitary operations and CNOT operations based on the result of the measurement And the receiver can obtain a four-qubit cluster-type state |?>= a|0000>+ bei?1|0011>+ cei?2|1100>+ dei?3|1111>.Comparing with other similar probabilistic schemes,the success ratio of our scheme is 1,which belongs to the deterministic scheme,and the EPR pairs are easier to be prepared in current physical experiment.(3)With the basis of analysis on the quantum computation based on measurement and the universal blind quantum computation,we propose a basic protocol for multi-party blind quantum computation.The protocol,combined with the possible future application model of quantum computation,limits the client to classic users merely with quantum channels.With the servers' collaboration,clients can complete quantum computing tasks and keep the blindness of computation information.Meanwhile,we analyze the blindness and security of basic protocols,especially the damages caused by channel noises,external attacks and possible servers' attacks.Based on the above research,we modify the basic protocol and present a secure multi-party blind quantum computation protocol with noise and security detection.This protocol can detect the channel noises and servers' attacks during the blind quantum computation process,which guarantees high security and wide application.(4)In essence,blind quantum computation is the encryption computing based on the measurement-based quantum computation,and is equivalent to quantum circuits'computation.Blind quantum computation accomplishes the computing task by simulating the quantum logic gates in the quantum circuit.Therefore,the size of quantum circuit will determine the resource efficiency and computational efficiency of the blind quantum computation.Based on the study on the template optimization technique of quantum circuit,we propose the synthesis algorithm for quantum template circuit based on genetic algorithm.The experiment proves that the algorithm does not have any computing and storage limit,and can get any size of the template circuit,which improves capabilities of optimizing the quantum template circuit The template circuit can optimize the quantum circuit.As a result,the scale of the quantum circuit and the use of blind quantum computation resources can be reduced,and the efficiency of the computation will be improved.In summary,this dissertation puts forward its own solutions and concepts for the construction,security and applicability of basic protocols and application protocols for secure multi-party quantum computation,enriches and develops the research on secure multi-party quantum computation.