基于四粒子cluster态的四方半量子密钥协商协议

为了满足多用户安全通信的需求,利用四粒子cluster态的纠缠特性和测量-重发操作提出一个四方半量子密钥协商协议。该协议能够使一个全量子方和三个半量子方在无可信第三方协助的情况下进行密钥协商,并公平地建立共享密钥。由于该协议的半量子方仅需执行简单量子态制备、测量和反射操作,因此该协议降低了对参与者能力和设备的要求。研究结果表明,该协议在有效地抵御参与者攻击和所有外部攻击的同时具备良好的性能。     

基于三粒子W态的身份认证

无认证中心的认证协议一般由通信双方相互认证.事先共享纠缠态或身份密钥,结构简单,但不适于扩展成通信网络.通过引入可信第三方认证中心,并利用三粒子W纠缠态的稳健性,提出了一个基于W态的身份认证协议,使得合法通信用户可以在认证中心的协助下进行安全身份认证,身份认证的同时即完成了纠缠粒子的分发.认证完成后,合法通信用户可安全共享EPR纠缠态并在第三方的控制下进行量子直传通信.针对窃听者常用攻击手段进行了安全性分析,结果表明在身份认证过程中可以有效的抵御伪装攻击,截取重发攻击与纠缠攻击等.基于第三方的通信结构具有可扩展性、实用性和受控性.     

基于GHZ态的三方量子确定性密钥分配协议

基于连续变量GHZ态的纠缠特性,提出一种三方量子确定性密钥分配协议,其中密钥由GHZ态的振幅产生,而相位可以用来验证信道的安全性.现有的量子确定性密钥分配协议一次只能向一个接收方传送密钥,现实生活中经常要向多个接收方发送确定性密钥.信息论分析结果表明,当信道传输效率大于0.5时,该协议可以同时向两个接收方安全传送确定性密钥,制备多重纠缠态后,该协议还能够扩展成多方量子确定性密钥分配协议,这极大提高了密钥的整体传送效率,而且连续变量量子GHZ态信道容量较高,因此该协议具有重要的现实意义.     

基于二进制均匀调制相干态的量子密钥分发方案

提出了一种基于二进制均匀调制相干态的量子密钥分发方案. 相对于高斯调制相干态量子密钥分发方案中的高斯信源,二进制信源是最简单的信源,二进制调制是目前数字光纤通信中最普遍的调制方式,技术上容易实现. 采用Shannon信息论分析了该协议抵抗光束分离攻击的能力,得到秘密信息速率与调制参数、解调参数以及信道参数之间的解析表达式. 关键词： 量子密钥分发 二进制调制 光束分离攻击     

多方控制的量子安全直接通信协议的分析及改进

对一种多方控制的量子安全直接通信协议(WCZT协议)进行了安全性分析,并利用隐形传态给出了一种新的攻击方法.利用该攻击方法,接收方可以在没有征得任何控制方同意的情况下获得发送方的消息,因此该协议是不安全的.对该协议进行了改进,分析表明改进后的协议能够抵抗这种攻击,可以满足多方控制的量子安全直接通信的目的. 关键词： 隐形传态 单光子 多方控制 量子安全直接通信     

量子密钥分发中Cascade协议的一种改进方案

密钥协商是量子密钥分发(QKD)中的重要组成部分.Cascade协议是实际中使用最广泛的量子密钥协商协议.本文基于[6]的工作提出一种对Cascade协议的改进方案.计算机仿真显示我们的方案比原始Cascade和一些其它改进方案有更高的效率.     

基于双模压缩态的量子密钥分发方案

提出了一种基于双模压缩态的量子密钥分发方案，采用Shannon信息论分析了该协议抵抗光束分离攻击的能力，得到秘密信息速率与压缩因子、信道参数之间的解析表达式，双模压缩态的模间关联性保证了该方案的安全性.     

具有强安全性的指定验证者量子签名方案

多数传统的指定验证者签名方案无法抵抗量子计算机的攻击.本文给出一种具有强安全性的指定验证者量子签名方案.在方案中,参与方利用量子密钥分配协议和量子直接通信协议共享密钥.密钥生成中心制备Bell态序列并将其分配给签名者和指定验证者.签名者利用其密钥和受控量子态对消息进行签名.同时,指定的验证者可以利用对称的签名步骤对量子签名进行仿真.而验证者仿真的量子签名与签名者产生的量子签名完全一样.这使得量子签名具有不可传递的属性.本文所给出的签名方案可以抵抗伪造攻击,截获重放攻击和木马攻击.并且,其理论上的信息安全属性可以得到证明.同时,密钥生成中心无需完全可信.方案无需使用量子单向函数.当产生量子签名时,签名者无需制备纠缠态序列.当验证签名时,验证者无需执行量子态比较算法.方案的量子比特效率达到100%.因此,与类似方案相比,本文所给的方案具有较好的安全性和效率.     

基于量子远程通信的连续变量量子确定性密钥分配协议

基于量子远程通信的原理, 本文借助双模压缩真空态和相干态, 提出一种连续变量量子确定性密钥分配协议. 在利用零差探测法的情况下协议的传输效率达到了100%. 从信息论的角度分析了协议的安全性, 结果表明该协议可以安全传送预先确定的密钥. 在密钥管理中, 量子确定性密钥分配协议具有量子随机性密钥分配协议不可替代的重要地位和作用. 与离散变量量子确定性密钥分配协议相比, 该协议分发密钥的速率和效率更高, 又协议中用到的连续变量量子态易于产生和操控、适于远距离传输, 因此该协议更具有实际意义.     

基于四态协议的半量子密钥分发诱骗态模型的有限码长分析

半量子密钥分发允许一个全量子用户Alice和一个经典用户Bob共享一对由物理原理保障的安全密钥.在半量子密钥分发被提出的同时其鲁棒性获得了证明,随后半量子密钥分发系统的无条件安全性被理论验证. 2021年基于镜像协议的半量子密钥分发系统的可行性被实验验证.然而,可行性实验系统仍旧采用强衰减的激光脉冲,已有文献证明,半量子密钥分发系统在受到光子数分裂攻击时仍旧面临密钥比特泄露的风险,因此,在密钥分发过程中引入诱骗态并且进行有限码长分析,可以进一步合理评估密钥分发的实际安全性.本文基于四态协议的半量子密钥分发系统,针对仅在发送端Alice处加入单诱骗态的模型,利用Hoeffding不等式进行了有限码长情况的安全密钥长度分析,进而求得安全密钥率公式,其数值模拟结果表明,当选择样本量大小为10⁵时,能够在近距离情况下获得10^-4bit/s安全密钥速率,与渐近情况下的安全密钥率相近,这对半量子密钥分发系统的实际应用具有非常重要的意义.     

Three-Party Quantum Key Agreement Protocol Based on Continuous Variable Single-Mode Squeezed States

The difficulty of quantum key agreement is to realize its security and fairness at the same time.This paper presents a new three-party quantum key agreement protocol based on continuous variable single-mode squeezed state.The three parties participating in the agreement are peer entities,making same contributions to the final key.Any one or two participants of the agreement cannot determine the shared key separately.The security analysis shows that the proposed protocol can resist both external and internal attacks.     

Three-Party Quantum Key Agreement with Two-Photon Entanglement

A three-party quantum key agreement protocol with two-qubit entangled states is proposed. In this paper, the three parties are entirely peer entities and each party has a equal contribution to the establishment of the shared secret key. Moreover, any subset of the three participants except the universal set can not determine the shared key alone. Finally, the security analysis shows that the present protocol can resist against both the outsider attack and the insider attack.     

Mediated Semi‐Quantum Key Distribution Without Invoking Quantum Measurement

This paper proposes a new semi‐quantum key distribution protocol, allowing two “classical” participants without sophisticated quantum capability to establish a shared secret key under an untrusted third party (a quantum server). The proposed protocol is free from several well‐known attacks. Furthermore, the efficiency is better than the existing three‐party SQKD protocol in which the classical participants must have the quantum measurement capability.     

Novel Multi-Party Quantum Key Agreement Protocol with G-Like States and Bell States

A significant aspect of quantum cryptography is quantum key agreement (QKA), which ensures the security of key agreement protocols by quantum information theory. The fairness of an absolute security multi-party quantum key agreement (MQKA) protocol demands that all participants can affect the protocol result equally so as to establish a shared key and that nobody can determine the shared key by himself/herself. We found that it is difficult for the existing multi-party quantum key agreement protocol to withstand the collusion attacks. Put differently, it is possible for several cooperated and untruthful participants to determine the final key without being detected. To address this issue, based on the entanglement swapping between G-like state and Bell states, a new multi-party quantum key agreement protocol is put forward. The proposed protocol makes full use of EPR pairs as quantum resources, and adopts Bell measurement and unitary operation to share a secret key. Besides, the proposed protocol is fair, secure and efficient without involving a third party quantum center. It demonstrates that the protocol is capable of protecting users’ privacy and meeting the requirement of fairness. Moreover, it is feasible to carry out the protocol with existing technologies.     

Quantum secure direct communication with Greenberger-Horne-Zeilinger-type state （GHZ state） over noisy channels

We propose a quantum error-rejection scheme for direct communication with three-qubit quantum codes based on the direct communication of secret messages without any secret key shared in advance. Given the symmetric and independent errors of the transmitted qubits, our scheme can tolerate a bit of error rate up to 33.1%, thus the protocol is deterministically secure against any eavesdropping attack even in a noisy channel.     

Three Attacks on the Mediated Semi-Quantum Key Distribution without Invoking Quantum Measurement

Semi-quantum key distribution is a very interesting new branch of quantum key distribution. It can be implemented when one or more participants are restricted to operate quantum states only on the quantum computational basis. Very recently, a mediated semi-quantum key distribution protocol without invoking two participants' quantum measurement has been proposed. The protocol allows two “classical” participants without sophisticated quantum capability to establish a shared secret key under an untrusted third party. It is claimed that the protocol is secure against several well-known attacks. However, in this paper, it is first pointed out that there exist three attacks “Measurement Attack, Modification Attack, and Collective Attack” on the mediated semi-quantum key distribution protocol without invoking quantum measurement. By proposed attacks, a malicious third party can obtain the secret key without being noticed by legitimated participants.     

A New Quantum Multiparty Simultaneous Identity Authentication Protocol with the Classical Third-Party

To guarantee information security in communication, quantum identity authentication plays a key role in politics, economy, finance, daily life and other fields. In this paper, a new quantum multiparty simultaneous identity authentication protocol with Greenberger–Home–Zeilinger (GHZ) state is presented. In this protocol, the authenticator and the certified parties are the participants with quantum ability, whereas the third party is a classical participant. Here, the third-party is honest and the other two parties may be dishonest. With the help of a classical third-party, a quantum authenticator and the multiple certified parties can implement two-way identity authentication at the same time. It reduces the quantum burden of participants and lowers down the trustworthiness, which makes the protocol be feasible in practice. Through further security analysis, the protocol can effectively prevent an illegal dishonest participant from obtaining a legitimate identity. It shows that the protocol is against impersonation attack, intercept-measure-resend attack and entangle-measure attack, etc. In all, the paper provides positive efforts for the subsequent security identity authentication in quantum network.     

A Multi-party Quantum Key Agreement Protocol Based on Shamir’s Secret Sharing

Quantum networks can extend the advantages of quantum key distribution protocols to more than two remote participants. Based on Shamir threshold secret sharing scheme, a new quantum key agreement protocol on a quantum network with any number of participants is proposed. First, each participant and distributor negotiate a sub-secret key using a kind of quantum key distribution protocol, and then each of these participants, as distributor, shares these sub-secret keys with other participants using Shamir threshold secret sharing scheme. Furthermore, each participant combines all these shared sub-secret keys and his own sub-secret key in sequence to form secret key, and sends the hash function values of this secret key to the master distributor to authenticate, finally they obtain the security key. Our scheme is practical and secure, and it can also prevent fraudulent from participants.

     

Analysis of a kind of quantum cryptographic schemes based on secret sharing

Recently, Yang et al. proposed a kind of quantum cryptographic schemes based on secret sharing. The main idea is drawn from the case, where any n participants who share a secret K can co-operate as K does. This process can be applied to encryption, authentication, signature and so on. Unfortunately, since there is no identity authentication of the share’s holder, these schemes inherit the limitation of secret sharing in practice. If some participants do not follow the protocol, the protocol would be a failu...     

Security analysis on some experimental quantum key distribution systems with imperfect optical and electrical devices

In general, quantum key distribution （QKD） has been proved unconditionally secure for perfect devices due to quantum uncertainty principle, quantum noneloning theorem and quantum nondividing principle which means that a quantum cannot be divided further. However, the practical optical and electrical devices used in the system are imperfect, which can be exploited by the eavesdropper to partially or totally spy the secret key between the legitimate parties. In this article, we first briefly review the recent work on quantum hacking on some experimental QKD systems with respect to imperfect devices carried out internationally, then we will present our recent hacking works in details, including passive faraday mirror attack, partially random phase attack, wavelength-selected photon-number-splitting attack, frequency shift attack, and single-photon-detector attack. Those quantum attack reminds people to improve the security existed in practical QKD systems due to imperfect devices by simply adding countermeasure or adopting a totally different protocol such as measurement-device independent protocol to avoid quantum hacking on the imperfection of measurement devices [Lo, et al., Phys. Rev. Lett., 2012, 108： 130503].