Theoretical Research On Quantum Digital Signature

In the historical process of human society,confidential communication is always playing an important role.With the rapid development of science and technology,not only in the field of national defense security,but also in finance,commerce,as well as personal privacy,people hope that information can be safely and effectively guaranteed.Traditional encryption algorithms are based only on mathematical computational complexity and can not give a strict proof of security.With the deepening of information science and technology research,traditional encryption algorithms will be severely challenged with the emergence of quantum computers.The emergence of quantum cryptography has undoubtedly given people the most powerful answer,making up for the shortcomings of the previous encryption algorithms.As an important branch of people’s research on quantum secret communication,quantum digital signature（QDS）has achieved fruitful results on the road of practical use.In this paper,we first review the research background,significance and development status of quantum digital signature.Then we will introduce the quantum key distribution protocol which closely related to quantum digital signature,and we focus on the decoy-state quantum key distribution（QKD）protocol that can resist the photon-number-splitting attack（PNS）.After introducing the basic knowledge of QDS,we describe the QDS protocol process and the key generation protocol（KGP）based on BB84 protocol,and give a detailed security analysis of the QDS protocol.Finally,we summarize the work we have done on this basis,mainly including the following ways:1.We overcome the computational complexity and time-consuming problems caused by optimizing the signature rate.Guaranteed that the protocol security level is 10^-4,the signature rate of the QDS continuous distance based on BB84 protocol using weak coherent light source（WCS）is given.And further optimize the variable parameters,so that the system’s signature rate and secure transmission distance have been greatly improved.2.WCS has a non-negligible vacuum component,which limits the safe transmission distance of the communication system at long distance.We propose a QDS scheme using heralded single photon source（HSPS）.The new scheme makes up for the shortcomings of WCS to the signature system,and analyzes and compares it with the help of numerical simulation.3.In order to solve the problem of modulated pulse signals generated by active decoy in QDS,we propose a passive decoy signature scheme based on linear optics.The new scheme replaces the modulation of the intensity of the light source through the response and non-response events in the detector,avoiding the safety hazard problems such as leakage pulse width and frequency information which are easily caused by the pulse modulation process,and further improving the safety performance of the system.