【作者】 李明达；

【导师】 刘天华；

【作者基本信息】 沈阳师范大学 ， 计算机应用技术， 2012， 硕士

【摘要】 保密通信指的是在数据通信过程中通过加密或其他手段，隐藏信息真实内容的一种通信方式，最初是出于政治、军事领域的需要，随着其日益发展，目前已越来越多的应用于各个领域中。目前大多应用的保密通信还是基于传统密码学。随着密码学和信息安全技术的进步，传统密码学中许多已证明是安全的算法在量子密码学中都不再安全。本文从论述量子密码学的基本原理开始，详细介绍量子通信中典型量子密钥分配协议的通信原理及实现过程。量子密码学(Quantum Cryptography)是以经典密码学和量子力学为基础、利用量子力学中微观粒子的基本属性和原理实现的一种新型密码体制，是对基于数学理论的传统密码的延伸。其区别于传统密码学的本质在于提供了唯密文无条件安全性和监听窃听者存在与否的能力，在量子力学的原理保证下完成了真正无条件安全的保密通信。目前，研究者们对单量子态密钥分发协议的安全性研究，无论从理论还是实验方面，都已非常成熟，一些技术已从实验室走出为保密通信做出贡献。而研究者们也将研究重心转向对量子密钥分发协议的不断改进，比如如何提高量子比特利用率、密钥生成率以及可容忍错误率等。然而，量子密钥分发体制提供的是理论上唯密文的无条件安全性，在现实设备条件下，攻击依然存在。本文在前人研究成果的基础之上，首先详细研究了窃听者Eve常用的攻击方法并分析其产生的原因、攻击的原理以及攻击过程；结合目前量子密码协议，研究上述各种攻击方法能否对各种协议造成威胁，即目前的密码协议在各种攻击方法面前的漏洞。其次，对已有协议的研究和完善，在基于纠缠态-W态的量子密钥分配协议中的窃听检测阶段，CA、Alice和Bob随机选取一些粒子进行窃听检测，根据Bell-CH不等式给出窃听检测的具体方案，结果表明：该方案优于已有的一些方案，如哈代证明，能够更为灵敏的检测出Eve的窃听。更多还原

【Abstract】 Secure communication is a means of communication for the purpose of hiding the realinformation content in the process of data communication by encryption or some other means. Itfirst originated in the field of the political sphere and the military field , as the development ofthe secure communication, it is now playing an important role in a lot of fields. The exitingclassical secure communication systems tend to basing on classical cryptography, which mostlyin view of computational complexity in the sense of difficult issues without rigorous certification.With the advances in cryptography and information security technology, a lot of those classicalcryptographic algorithms used to be proved secure is not secure anymore.In this paper, we begin with discussing the basic principles of quantum cryptography, thenwe introduce the theory and process of some of the classic quantum key distribution protocols.Quantum cryptography is a new cryptosystem based on the classical cryptography and quantummechanics, it uses the basic properties and principles of microscopic particles to transfer keyinformation and stretch classical cryptography. It provides not only unconditional security if onlythe eavesdropper has known the ciphertext but also the ability to detect eavesdrops. At present,the security of single-qubit quantum key distribution protocol has been considered thoroughlyand perfectly both in the theory and experimental study, and some of them has been usedperfectly in real life. Nowadays, researchers have focusd on the improvement of the existingquantum key distribution, for example: how to improve quantum bit utilization, the rate of keyand tolerable error rate and so on.However, quantum cryptography is only secure in the theory of quantum mechanics, Underrealistic device conditions, there are still some eavesdroppers.Generally speaking, we call aneavesdropper“Eve”. On the basis of the results of previous studies, In this paper, we first focusour research on Eve’s commonly used method of attack and analysis of the reason, principle andprogress of each manner of the attacks above; emphatically,we give the conclusion that whetherthose attacks can pose a threat to the protocols combined current quantum key distributionagreements. That is, loopholes of the agreements in front of these attacks.Then we research on and then perfect a quantum key distribution protocol to find a moresecure quantum key distribution protocol on the basis of entangled state–W state. Duringeavesdropping detection, CA、Alice and Bob will randomly choose some of the quantums todetect whether there is an eavesdropper. We use Bell-CH inequality in the stage of eavesdropping detection and it turns out to be a better scheme than some of the existing schemes, forexample:Hardy’s proof. Contrasting to pre-existing schemes, we given the concrete scheme ofeavesdropping detection which showing some better results such as sensibility, provability andother features based on Bell-CH inequality.更多还原