Study On Quantum Dialogue Protocols Without Information Leakage

Quantum communication is a new communication mode, which uses the basicprinciple of quantum mechanic to process and transmit information. Compared withthe classical communication technology, quantum communication has some merits:strong confidentiality, large capacity, high efficiency, etc. With the rapiddevelopment of quantum communication technology, quantum secure directcommunication has become on of the hot spots in the field of quantumcommunication, which based on quantum states as the carriers of information, it candirectly transmit secret messages without first establishing shared key.Quantum dialogue is a bidirectional quantum secure direct communication,where two communication parties are permitted to mutually exchange secretmessages at the same time. Two communication parties encrypt their secretinformation in quantum states by unitary transformation, each communication partycan deduce the secret messages of his counterpart according to the quantum initialstates, the final states and the secret messages of themselves, which achieves thesecret exchange. The security of quantum dialogue is protected by quantumno-cloning theorem and Heisenberg uncertainty principle. The auxiliary classicalcommunication must be opened in quantum communication, however, the secretmessages of quantum dialogue are easy leaked to eavesdroppers from the publicclassical communication of legitimate correspondent, which is known as informationleakage. Focusing on the hot subject of quantum dialogue without informationleakage, according to peculiarity of quantum state, Controlled-NOT operation, densecoding, two-step protocol and ping-pong protocol, three quantum dialogue protocolswithout information leakage are proposed. Furthermore, the security of eachquantum dialogue protocol is analyzed in detail from information theory. The mainresearch results are as follows:According to ping-pong protocol and Controlled-NOT operation, asingle-photons secure quantum dialogue protocol is proposed. Bob obtains theinformation of the encrypted quantum state by performing Controlled-NOT operation on the auxiliary particle and the encrypted single-photon. Compared withthe previous quantum dialogue protocols based on single-photon, the proposedprotocol not only overcomes information leakage but also possesses an acceptableefficiency.According to two-step protocol and Controlled-NOT operation, a quantumdialogue protocol is proposed based on triple particle W state, where Alice preparestriple particles W state and sends it to the receiver Bob in two steps: Alice sends oneof the triple particles W state to the receiver Bob, its purpose informs Bob that theinitial state of the remaining two quantum particles before carrying secret message;Alice encrypts her secret message into entanglement of the remaining two particlesof the triple particles W state, and then sends it to Bob. Each particle is transmittedonly once in the whole communication, which reduces the risk of eavesdropping andimproves the efficiency of the proposed protocol.Three quantum dialogue protocols with identification are proposed, they areused to resist collective-dephasing noise, collective-rotation noise and bothcollective noises, respectively. The proposed protocols structure generalized GHZstate by using the quantum states of Decoherence-free subspace which can resistcollective quantum noise, and achieve dense coding by using generalized unitarytransformation; The proposed protocols add authentication in the first eavesdroppingdetection, which can effectively avoid the middle attacks and improve the security ofprotocol. Moreover, the efficiency, the security and the information leakage of theproposed protocol are analyzed in detail from information theory and cryptography.