【作者】 权东晓；

【导师】 裴昌幸；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2009， 博士

【摘要】 量子通信由于其无条件安全性而得到了广泛的重视,取得了快速的发展。目前它的分支主要包括量子密钥分发、量子秘密共享、量子安全通信以及量子认证等。在量子密钥分发中,由于目前还没有实用的完美单光子源,通常采用弱相干光经过衰减近似地代替单光子源,因此可能存在光子数目分割攻击,诱骗态量子密钥分发的思想也就因此而产生了。并且随着量子通信的发展,点到点量子通信必然要过渡到多个用户的量子通信网络。本文主要对诱骗态量子密钥分发、量子秘密共享、量子安全通信和量子通信网络进行研究。论文的主要研究成果如下:在诱骗态量子密钥分发方面,首先从理论上仿真证明诱骗态方案确实能够识别光子数目分割攻击。其次推导了预报单光子源诱骗态量子密钥分发的密钥产生率公式,并进行了弱相干光和预报单光子源诱骗态量子密钥分发的最优强度估计和密钥产生率计算与仿真。研究表明:密钥产生率随着发送端探测效率的增加而增加;采用诱骗态后由于能够更好地估计出单光子的通过率,因此密钥产生率和安全通信距离都得到了提高。最后提出了一种基于预报单光子源的单一强度的诱骗态量子密钥分发方案:在发端采用参量下变换产生纠缠光子对,其中之一用来进行预报探测,根据探测结果将另一路光脉冲分成两个集合,其中预报探测有响应的脉冲集合用作信号态,无响应的脉冲集合作为诱骗态。通过这两个集合的通过率和错误率估计出单光子的通过率和错误率,并进行了密钥产生率的推导和数值仿真。研究表明:其安全通信距离与完美单光子源一致,虽然其密钥产生率和三强度诱骗态方案相比有所下降,但该方案不需要改变光强,实现起来更容易。在量子秘密共享方面,研究了基于单光子的多方与多方之间的量子秘密共享协议,发现如果发送方不注意公布编码基和编码信息的顺序,则并不需要所有的代理合作不诚实者就可以获得信息。提出了各个代理采用顺序公布编码信息逆序公布编码基的改进方案。研究了基于纠缠交换的量子秘密共享协议,发现如果不改变发送给同一个代理的两个粒子的相对顺序,则不诚实者可以通过攻击最终使得诚实者得到错误的密钥。然后提出了随机地改变发送给同一代理的两粒子顺序的改进方案。研究了基于纠缠交换的量子秘密共享协议,此协议由于让每一个代理来制备纠缠态而带来了不安全性。提出了新的基于纠缠交换的量子秘密共享协议,所有的纠缠态都由发送方来制备,并且随机地改变发送给同一个代理的两粒子的相对顺序。在接收方收到粒子后,如果是检测模式,发送方公布两粒子的顺序,双方进行窃听检测;如果是信息模式则两个接收方分别对各自的两个粒子进行联合测量,两者联合起来与发送方共享密钥。分析结果表明此协议能够保证共享信息的安全性和正确性。在量子安全通信方面,分析了已有的量子安全通信协议,提出了基于单光子的单向量子安全通信方案。发送方在对信息序列进行编码操作之前首先将其和随机序列进行异或操作并插入校验序列。接收方收到光子后对其进行延迟,然后发送方公布编码基从而使接收方在正确的基下进行测量。接着双方通过校验序列判断信道的安全性,如果信道安全,则发送方公布接收方有测量结果的位置所对应的随机序列,接收方由此恢复出信息序列;如果信道不安全,窃听者所获得的只是随机的发送序列,信息序列仍然是安全的。此协议与双向通信协议相比具有传输效率高,易于实现等优点。在量子通信网络方面,提出了量子通信网络和量子交换机的架构以及基于诱骗态的广域量子安全直接通信网络方案。该方案在每一个局域网中设置一个服务器负责量子态的产生和测量,从而有效地提高了通信距离;将诱骗态的思想引入量子安全直接通信以保证利用弱相干光代替完美单光子源时传输信息的安全性;并且根据信道参数估计了不同通信距离的通过率,为信道编码提供依据。分析结果表明此方案能够实现远距离量子安全直接通信。更多还原

【Abstract】 Because of the unconditional security ensured by the Heisenberg uncertainty principle and quantum no-cloning theory, quantum communication has progressed quickly. There are several remarkable branches of quantum communication, such as Quantum Key Distribution (QKD), Quantum Secret Sharing (QSS), Deterministic Secure Quantum Communication (DSQC), Quantum Authentication (QA) and so on. Since there is no practical perfect single photon source at present, the weak coherent pulses (WCP) are often used as a substitution in experimental and practical systems. The eavesdropper Eve may perform the photon-number-splitting (PNS) attack to get information, thus the idea of decoy-state QKD was born. With the development of quantum communication, Quantum Communication Network (QCN) will come into being. This dissertation is focused on decoy-state QKD, QSS, DSQC and QCN, the main contributions of this work can be summarized as follows:In the aspect of decoy-state QKD, firstly through simulation decoy states can be used to identify the PNS attack is proved; Secondly, the formulae for the quantum key generation rate of the decoy state QKD with a heralded single-photon source (HSPS) are deduced, the optimal intensities and the key generation rate of the decoy state QKD with WCP and HSPS are analyzed respectively. Analysis results show that the quantum key generation rate increases with the detection efficiency of the sender; the key generation rate and the security communication distance are increased for decoy state make the estimation of the yield of the single photon pulse more exact. Finally, a new method of decoy-state QKD with a HSPS is proposed. In this scheme, Alice uses the parametric down-conversion to generate entangled photon-pairs, one of the pair is used as heralding photon. By the results of the trigger detector the heralded photons are divided into trigger and non-trigger sets. The states of the photons in the trigger set are used as the signal states and the other ones in the non-trigger sets are used as the decoy states. The yield and error rate of the single-photon pulse are estimated through the yields and error rates of the two sets. The key generation rate is deduced and simulation results show that by this method the same security distance can be reached as with a perfect single photon source; although the key generation rate is approximate two thirds the rate of the three intensities decoy state QKD, but this method does not need change the intensity of the photon source, is easy to implement. In the aspect of QSS, firstly the protocol of QSS between multiparty and multiparty without entanglement is discussed, and it is easy to know that if the senders do not pay attention to the publishing orders of the basis and the information, the dishonest agent can get the information without the collaboration of all agents. The method by which the agents publish the information in order and the basis in reverse order is proposed. Secondly, the protocol of multiparty QSS of classical messages based on Entanglement Swapping is also discussed, and it is easy to know that if the order of the two photons sent to the same agent does not changed, the dishonest agent can attack the protocol and the honest agent will get wrong information. Thus a new method by which the two photons are sent to the same agent in random order is proposed. Finally, the protocol of QSS based on Entanglement Swapping is studied, and analysis results show that the protocol is not secure since the entanglement states are generated by each agent. Then a new method of QSS based on Entanglement Swapping is proposed, by which the entanglement states are all generated by the sender, and the order of two photons sent to the same agent are randomly changed. After the photons arrived at the receiver, in case of the detection mode, the order of the two photons is announced, the two parties detect the security of the quantum channel; in case of the information mode, the two receivers respectively do Bell measurement on the two photons they own. Then the receivers communicate through classical channel to share the secret key with the sender. Analysis result shows that this protocol can ensure the security and correctness of the shared information.In the aspect of DSQC, based on the analysis of the proposed protocols, One-way DSQC protocol based on single photons is proposed. In this protocol, the XOR operation by bits of the information sequence and random sequence is performed and a checking sequence is inserted before the sender’s coding operation. When the photons arrive at the receiver, they are delayed at the receiver and the sender then publishes the coding basis, so the photons can be measured in the correct basis. Then the two parties estimate the security of the quantum channel by the checking bits. When the channel is secure the sender publishes the random bits where the receiver has results, and the information sequence can be recovered by the receiver. Even the channel is not secure, what the eavesdropper gets is the random sending sequence, the information sequence is still secure. This protocol has the advantages of higher transmission efficiency and easier implementation compared with the two-way communication.In the aspect of QCN, a scheme for QCN and quantum switch is suggested. Moreover, a scheme for wide-area Quantum Secure Direct Communication (QSDC) network based on decoy states is proposed. A Server used to prepare and measure photons is set in each local area network, so the communication distance is increased. In addition, the idea of decoy states is introduced to QSDC to ensure the security of the communication when WCP is used. Moreover, the transmission probability is estimated based on the channel parameter, which can be used as a reference for channel coding. Security analysis result shows that this protocol can be used to realize long distance QSDC.更多还原