The Research Of Quantum Secret Sharing Protocol

Quantum cryptography is formed by the combination of cryptography with quantum theory,which has attracted much attention in recent 20 years.As an important branch of quantum cryptography,quantum secret sharing(QSS)is developing rapidly.It can effectively manage the secret key of quantum secret communication,and the basic idea is that a secret message is divided into several pieces by the sender,and only the whole pieces collaborate together can the secret message be reconstructed.Otherwise,any one of them cannot be sufficient to deduce the sender's secret message.For the classical secret sharing(SS),it will not be able to detect eavesdropping in the process of the key transmission.And in QSS,the key transmission and eavesdropping detection can exist simultaneously.Compared with the classical SS,QSS is more secure.However,due to the designers is thoughtless,some QSS protocols are unsafe.The thesis focuses on the study of design and the security of QSS,and the mainly works are as follows:(1)Semi-quantum secret sharing(SQSS)protocol based on rearranging orders of qubits.In 2016,Gao et al.proposed SQSS protocol based on rearranging orders of qubits.By analyzing the security of their protocol,we show that if the last agent and other agents adopt some attack strategy,they can illegal get the secret key of the sender without being detected.Furthermore,we propose an improved protocol.(2)SQSS protocol of specific bits.Due to the shared key in most of present QSS protocols is random bit string,Xie et al.proposed a protocol in which the specific bits are shared.By analyzing it,we find that their protocol is not secure and give a proof.If a dishonest participant adopts intercept-resend attack,he can obtain the sender's key without the cooperation of other participants.In addition,we also put forward a improved protocol.(3)SQSS protocol based on Bell states.Compared to other types of QSS,SQSS can use less quantum resources to complete the key sharing.Because the preparation of quantum state is expensive,SQSS has the high practical value.So we propose a novel SQSS protocol.In our scheme the keys of participants are randomly produced,which reduces the risk of leaks.