Detailed Security Analysis Of QKD System Based On BB84 Protocol

Considering the rapid development of quantum technology,it has become inevitable to use this technology to develop an ultimately secured key exchange system.Quantum key distribution(QKD)technology has become more sophisticated,is expected to provide secure key distribution mechanism for the actual information security systems.The unique advantage of quantum cryptography is precisely its ability to guarantee absolute security.Previous works have demonstrated unconditional security of the ideal BB84 QKD system.However,on a typical QKD system,many practical situations often cannot satisfy the requirements of the ideal condition.This problem causes some security issues for practical QKD system.Therefore,it is necessary to analyze the security of QKD system under practical conditions,and identify the security implications on the practical physical systems and equipment,so as to find a method that guarantees the security of QKD system.BB84 protocol has proven to be more practical,consistent and robust compare to other algorithms recently proposed.We propose the Shannon bound for sifting of codes which is guaranteed to be more reliable and has lesser key information leakages.The security of QKD system based on BB84 involves many aspects;this paper mainly focuses on how to resolve security issues that may exist,especially in the BB84 protocol post-processing.We introduce ways to tackle these issues and make vital key information leakage very small.Their impact on the security of entire QKD system is analyzed,and the interaction and security optimization between the various parts is researched.Firstly,for the BB84 protocol security,the evidence of the ideal BB84 protocol from information theory and entanglement purification is given,and the practical BB84 protocol security under the conditions of non-ideal light is also discussed,the formula of secure key extraction rate for the theoretical model GLLP(Gottesman Lo Lutkenhaus Preskill)is given.Then,the thesis puts forward optimization scheme with some security problems because of the non-ideality of equipment.Describes the optical equipments cause four attacks:PNS(Photon number splitting)attacks,Trojan attacks,Fake-state attack,Time-shift attack;and the defensive strategies corresponding four attacks.Thereby,the basics are provided for enhancing the security of practical QKD system.Finally,the thesis briefly introduces five sub-modules of post-processing of QKD system:the base comparison,error estimation,information correction,data check and privacy amplification;the existent security factors of each module is given,a security model with those issues is provided.Thus the security model of post-processing is further optimized.