The Protocol Design And Security Analysis Of Quantum Key Agreement

Quantum cryptography is an interdisciplinary research area,which is based on classical cryptography and quantum mechanics.Different with the security of clas-sical cryptography that relies on the assumption of computation complexity,the se-curity of quantum cryptography is ensured by the principles of quantum mechanics,which make it unconditionally secure.Therefore,quantum cryptography has drawn a lot of attention and has made significant progress in both theory and experiment recently.Nowadays,quantum cryptography has branches off some research issues,e.g.,quantum key distribution,quantum secret sharing,quantum private compari-son and quantum key agreement.Quantum key agreement is using the principles of quantum mechanics to nego-tiate a secure key.In a key agreement protocol,the shared key is negotiated by all users and any nontrivial subset of users cannot predict or determine the shared key alone.Thus,in a quantum key agreement protocol,the security requirement should be satisfied firstly,i.e.,a secure shared key is generated.Then,it should meet the fairness requirement,which means that all users contribute to the generation of the shared key equally.Finally,the privacy of each user's input is protected,and a high efficiency is achieved.This paper attempts to study the designing methods of quantum key agreement,and utilize various characteristics of quantum mechanics to design three protocols,which are listed as follows.1.Multi-party quantum key agreement without entanglement.In this protocol,four rotation operations which cannot be discriminated perfectly are used as encoding operations.Based on the properties of encoding operations,the private key of users can be protected efficiently.The security analysis shows that this protocol can resist against the outside attack and inside attack under ideal conditions.Moreover,the practical security of the protocol is discussed briefly.2.Multi-party quantum key agreement with teleportation.In this protocol,the states of signal particles are transferred between two adjacent users by the tech-nique of quantum teleportation.Besides,the technique of entanglement purifi-cation is adopted to ensure the purity of the shared particles.Thus,the final shared key established by this protocol can be used to encrypt secret message directly in real life.The security analysis shows that this protocol is secure against the outside attack and inside attack.3.Multi-party quantum key agreement over collective noise channels.In this pro-tocol,two classes of multiparticle entangled states are constructed to repel col-lective noise.Therefore,this protocol puts forward two propositions and proves their sufficiency and necessity.Based on the interesting properties of the en-tangled states,all users can do the security test and share the secret key.The security analysis shows that this protocol can resist against some common at-tacks efficiently.