Research On Design Of Quantum Cryptography Protocol And Application Of Quantum Search Algorithm

With the fast development of communication technology and computer research,information exchange among us becomes much wider and more frequent, thus information security appears more and more important. However, as human computing power is improved significantly, especially the presence of the quantum parallel algorithms, the security of classical cryptosystem based on computational complexity assumptions is severely compromised. Quantum cryptography is the combination of quantum mechanics and classical cryptography, whose unconditional security is guaranteed by the fundamental laws of quantum mechanics despite of the computational ability of the eavesdropper. Therefore, quantum cryptography attracts great attention and its research scope is very extensive, such as quantum key distribution, quantum secret sharing, quantum identity authentication, and quantum secure direct communication. Current theories and experiments show that the quantum cryptography will play an important role in the next generation of information security field.This paper mainly studies the quantum secret sharing and quantum secure direct communication protocol, and also does some exploration in the design of quantum algorithm. Some original research achievements are arranged as follows:1. As for the design of the quantum secret sharing protocol, this paper proposes a dynamic multi-party and multi-party quantum secret sharing scheme by constructing two different clusters of states to meet the need of sharing secret information between dynamic changeable users and groups. In addition to these demands, the producer of secret keys can also recover the secret information through the cooperation of all key members. Meanwhile, on account of the unique properties of entangled cluster states, which can resist attacks and internal members spoofing attacks, except the particles used to detect eavesdropping, the rest all of the recovery are involved in secret sharing, so the project also owns high security and efficiency.2. In the quantum secure direct communication part, based on two particles partially entangled states, we propose an efficient quantum secure direct communication scheme. Communicating parties encode the secret message by controlled NOT and local unitary operations. Using the von Neumann measurement, efficient two-way direct delivery can be realized combined with classic secret message communication. Due to the shared asymmetric quantum channels and different coding operations, when recovering the secret message, communicating parties each holds key quits to which the attacker has no access, which makes the protocol safe in an ideal or noisy channel.3. In the aspect of quantum computation algorithm, based on disordered Grover quantum search algorithm and birthday attack, we improve the original quantum collision search algorithm. At the same time, combining with Meet-in-the-middle attack, we realize the effective collision search of classic New FORK-256 in complexity 74.7?(2) and prove the accuracy and high efficiency of the improved method. Finally, the attack efficiencies of different programs are compared in details.