Information In The Public Channel Key Negotiation Coordination

Information security is a very significant issue,Cryptography is one of the efficient methods that protects the secret information from being eavesdropped.The computational cryptography is based on the unproved computational assumptions.However,with the development of computer science and the breakthrough of the quantum computer,the information security mechanism depending on the conventional mathematical cryptography will face the challenges.Quantum cryptography is based on both the conventional cryptography and quantum physics.Its security is guaranteed by the fundamental laws of physics.Both quantum no-cloning and the Heisenberg uncertainty relation ensure the absolute security and the ability of detecting eavesdropper.These facts guarantee that quantum cryptography has the excellent capacity and the attractive foreground.As an important research issue of quantum cryptography,quantum key distribution(QKD) is the most promising quantum information technology.However,due to the difficulty in both single photon generation and detection,the transmission rate of discrete variable QKD and quantum secure direct communication is very low.Key Agreement of Quantum Key Distribution is combined with the interruptive channel,discrete memoryless broadcast channels and satellite radio channel to constitute a unconditional security model secret consultations by Wyner,Csiszar,Korner,Maurer and others.Such a scenario can be abstracted from quantum channels and noisy channels.Two communicants,Alice and Bob,and an adversary,Eve,receive three variables X,Y,Z which are distributed according to some probability distribution P_XYZ. Then Alice and Bob begin secret-key agreement over a public channel.Such a secret key agreement over a public channel usually consists of three phases:advantage distillation,information reconciliation and privacy amplification,but advantage distillation isn't required for the quantum secret-key agreement.The main work in this thesis is as follows:(1) Summary of data-processing model public consultations before information reconciliation,the priority of the extraction protocol has been elaborated,and the protocol analysis from the view of probability and information theory,proving the feasibility of the protocol,calculating the boundaries of information leaked in protocols and the impact of finally key.(2) From the view of mathematics proof,the theoretical basis of the key agreement has been elaborated; revealing the relationship between the key rate and the correlation coefficient of the original string;in the open channel of consultations;researching the impact of the disclosure information which been disclosed in the information reconciliation process between Alice and Bob in Eve's Renyi entropy,revealing the relationship between information reconciliation and privacy amplification and at the basis of information theory derivating the sector and lower bounds of finally key which come from two strings not exactly same by secret-key agreement.(3) Detailing the classic information reconciliation protocols:BBBSC algorithm,Cascade protocol, Winnow algorithm,Distillation and Reconciliation combination of protocol,doing Analysis of the number of communication and those information leaked to Eve on the classical channel in the protocol process,as well as the impact of the finally key belong to eavesdropper and legitimate communication.