Design And Analysis On Multi-Party Quantum Key Agreement Protocols

Quantum cryptography is the combination of quantum informatics and classical cryptography.Unlike classical cryptography relying on computational complexity as the basis of security,quantum cryptography is mainly based on the Heisenberg Uncertainty Principle and the quantum no-cloning theorem,and unrelated to the mathematical computing power of eavesdroppers.The method combining quantum key distribution with one time pad can ensure that the whole communication process achieve theoretical unconditional security.In recent years,with the continuous expansion of the applications of quantum cryptography,quantum key agreement(QKA),a new direction of quantum cryptography,has become one of the research focuses.The shared key in the QKA protocol is determined by all participants contribute to the final shared key fairly and equally.Any one of the participants cannot independently determine the shared key until the key agreement protocol is finished.In this dissertation,two multi-party QKA protocols are designed and analyzed.The specific work is as follows.Based on seven-qubit maximum entangled states,a three-party quantum key agreement protocol was proposed,in which each participant negotiates the shared key with different encoding methods.The utilization rate of the quantum states was greatly improved because of the high entanglement of the seven-qubit maximum entangled state and the joint measurement.Security analyses demonstrate that the QKA protocol can effectively resist Trojan horse attack,intercept-resend attack entangle attack and participant attack,and it can achieve unconditional security under ideal conditions.A two-party quantum key agreement protocol based on Bell state and G-like state was designed.The protocol creates the entanglement relationship between two independent quantum states with entanglement swapping,and derives the final shared key by entanglement swapping of the Bell states.Furthermore,a multi-party quantum key agreement protocol was constructed by the two-party quantum key agreement protocol(MQKA).The MQKA protocol is a circular quantum network.Finally,the efficiency analyses on the three-party quantum key agreement protocol based on seven-qubit maximum entangled states and the multi-party quantum key agreement protocol based on Bell state and G-like state were analyzed.By comparing with other protocols,the proposed protocols are securer and more efficient in terms of quantum resource,key generation rate and qubit efficiency.