Research Into Several Issues In Quantum Secure Communication

In the latter part of last century, scientists founded the conception of quantum cryptography on the basis of quantum mechanics.This encryption method uses quantum state as the key used for the encryption and decryption of information. Anyone who wants to decrypt the key changes the quantum state and doesn't obtain userful information. Compared with the classical encryption methods based on complex mathematic compution, quantum cryptography is "absolutely secure" in theory. And with the rapid exchange of information today, quantum cryptography has a broad prospect of application and significance in science.Theoretically, all the classical mathematic encryption compution methods may be decrypted and however complex mathematic ciphers' rule can be found.The creation of the first modern computer is for decrypting complex mathematic ciphers. With the rapid development of computers, the difficulty of decrypting mathematic cipher is more and more low. Especially, the research into quantum computer makes quantum cryptography most important. Thus,this paper mainly researchs into some issues about quantum cryptography, in particular, mainly researchs into quantum key distribution, quantum identity authentication, quantum secret sharing, quantum signature, quantum cryptographic algorithm, quantum secure direct communication and so on. Main achievements in this paper are summarized as follows:1. The coefficients of W state used for quantum key distribution are proved to be uniform in symmetrical form. The corresponding quantum key distribution scheme via W state is proposed. To insure the security of the proposed quantum key distribution protocol, the receiver chooses randomly the message mode or control mode asymmetrically. As compared with the quantum key distribution with GHZ states, the efficiency of the proposed scheme is low. The purpose of this scheme is just to prove that the states except for GHZ states can be used for quantum key distribution.2. A theoretical scheme for multi-user quantum authentication and key distribution in a network is proposed. Similar to the authentication architecture of the network in classical cryptography, a distributed client/server architecture with the...