Multidimensional Space Quantum Key Distribution Protocol Study

Quantum cryptography , which is a cross-discipline subject combining cryptography with quantum mechanics, has become a very significant issue; Quantum system has some unique attributes: the Heisenberg uncertainty principle and no-cloning theorem. Hence, eavesdropping on quantum carrier in quantum cryptography system may disturb the quantum state, which ensures the unconditional security of quantum cryptography. It is implied by the research both in theory and in experiment that quantum cryptography would grow up in the next generation of technologies in cryptography.The contributions of this dissertation are mainly on the design and analysis of the protocols of quantum cryptography, including quantum key distribution (QKD) quantum identity verification (QIV), quantum secret sharing (QSS) and quantum secure direct communication (QSDC). The details are as follows:Based on the introduction of quantum cryptography's basic knowledge including physics, mathematics system and information theory, the mainly protocols and frequently-used attacks are analyzed. Because the PNS attack is invalid to quantum key distribution based on entanglement swapping even the pulse source is not perfect, we propose a general quantum key distribution based on quantum entanglement and entanglement swapping, and using Bell-state measurement|Φ⁺ ,|Φ^- ,|Ψ⁺ ,|Ψ^-| to detect errors, prove the security of this protocols which can resist the intercept - resend attack or additional particle entanglement attack. This dissertation improves random sampling tests from a single-sample method to the multiple-sample one, and designs a new quantum key distribution on 4-dimensional Hilbert space which makes use of | 0 ,1||^?2å'Œ|| +) ,|^?2to measure. Classical information reconciliation and privacy amplification can replace the quantum error-correcting without damaging unconditional security in order to ensure the security. At last four-qubitχ–type entangled states is used in quantum key distribution where the transmission of four qubits is divided into two steps. This protocol is proposed to provedχ–type entangled states can resist different attacks such as intercept - resend attack or additional particle entanglement attack.