【作者】 冯晨旭；

【导师】 焦荣珍；

【作者基本信息】 北京邮电大学 ， 物理电子学， 2009， 硕士

【摘要】 量子密码是量子力学和密码学相结合的产物,它解决了经典密码体制的密钥分配的难题,是当今世界上最热门的前沿科学技术之一。量子密码的安全性由量子力学基本原理—测不准原理和单量子态不可克隆定理保证,所以在密钥分配过程中,公开信道中的数据不必担心被窃听。在本文中,我们研究了目前主要的三种量子密钥分配协议。对这三种协议可能进行的攻击进行了讨论,其中包括分光束攻击和截断-重发攻击。主要是对DPSK协议的安全性进行了讨论,针对可能进行的攻击,DPSK协议具有很高的安全性。在量子密钥分配中,单光子探测器是很重要的一个组成部分,它的性能的好坏决定了密钥生成率的大小。本文中主要讨论了两种单光子探测器的主要性能,InGaAs/InP雪崩二极管(APD)和升频探测器。我们把目前常用的单光子探测器和升频单光子探测器做了比较并得出了仿真结果。升频探测器的性能大大优于目前常用的InGaAs/InP单光子探测器。本文给出了BB84,BBM92和DPSK协议的安全通信速率公式,分析了协议对抗一些攻击的安全性问题。基于这些公式用实际的参数比较了三种协议中光纤QKD系统的性能,我们能得到比以前高出两个数量级的通信速率,而用到升频探测器后的通信距离比传统的探测器要大两倍多。此外,对协议的重要性也做了列举,对Eve可能进行的攻击也做了讨论。结论是简单有效的DPSK协议能具有250km的通信距离和很高的通信速率。更多还原

【Abstract】 Quantum cryptography, which is a combination of quantum mechanism and cryptology, solves the dilemma of the classical cryptography and has been developed as one of the most popular information technologies in the world. The security of quantum cryptosystems is guaranteed by the fundamental laws of quantum mechanism: the uncertainty principle and the non-cloning theorem, so we should not worry about eavesdropping when the quantum key distribution is operated in a public channel.Here we studied three main quantum key distributions which are most popular nowadays. And possible attacks towards these three protocols are also discussed, for example: the beam splitter attack and intercept-resend attack. The security of the DPSK protocol is mainly focused. As a result, the DPSK protocol is much stronger against the possible attack.In the quantum key distribution, the single photon detector is a very important component. Two kind of single photon detectors such as the InGaAs/InP APD and the up-conversion detector are discussed. The comparison of these two detectors is made. From the simulation result, it is proved that the performance of up-conversion detector is much better than the conventional detector.Finally, the expressions of secure communication rate of three protocols are given based on the possible attack. Moreover, from these formulations, the performances of three protocols are compared. Then we found that a secure communication rate of two orders of magnitude higher than before is possible. And when the up-conversion detector is applied, the communication distance is two times longer than before. Furthermore, the importance of the implemented protocol was illustrated, and the impact of Eve’s allowed capabilities was investigated. It is concluded that the simple and efficient DPSK protocol allows for more than 200km of secure communication distance with high communication rates.更多还原