Security of quantum key distribution using two-mode squeezed states against optimal beam splitter attack

For the beam splitter attack strategy against quantum key distribution using two-mode squeezed states, the analytical expression of the optimal beam splitter parameter is provided in this paper by applying the Shannon information theory. The theoretical secret information rate after error correction and privacy amplification is given in terms of the squeezed parameter and channel parameters. The results show that the two-mode squeezed state quantum key distribution is secure against an optimal beam splitter attack.     

Multiparty simultaneous quantum identity authentication with secret sharing

Two multiparty simultaneous quantum identity authentication (MSQIA) protocols based on secret sharing are presented. All the users can be authenticated by a trusted third party (TTP) simultaneously. In the first protocol, the TTP shares a random key K with all the users using quantum secret sharing. The ith share acts as the authentication key of the ith user. When it is necessary to perform MSQIA, the TTP generates a random number R secretly and sends a sequence of single photons encoded with K and R to all the users. According to his share, each user performs the corresponding unitary operations on the single photon sequence sequentially. At last, the TTP can judge whether the impersonator exists. The second protocol is a modified version with a circular structure. The two protocols can be efficiently used for MSQIA in a network. They are feasible with current technology. Supported by the National Basic Research Program of China (973 Program) (Grant No. 2007CB311100), the National High Technology Research and Development Program of China (Grant Nos. 2006AA01Z419 and 20060101Z4015), the Major Research Plan of the National Natural Science Foundation of China (Grant No. 90604023), the Scientific Research Common Program of Beijing Municipal Commission of Education (Grant No. KM200810005004), the Scientific Research Foundation for the Youth of Beijing University of Technology (Grant No. 97007016200701), the National Research Foundation for the Doctoral Program of Higher Education of China (Grant No. 20040013007), the National Laboratory for Modern Communications Science Foundation of China (Grant No. 9140C1101010601), and the Doctor Scientific Research Activation Foundation of Beijing University of Technology (Grant No. 52007016200702)     

利用SPKI委托证书实现分布式访问控制

传统的访问控制技术已经无法满足大规模、跨域范围分布式应用的安全需要。本文从分析简单公钥基础设施（SPKI）委托证书满足分布式访问控制的几个基本特征出发，描述了证书的结构和五元组压缩规则，给出了采用委托证书的访问控制实现模型，最后简单讨论了委托证书链的搜索决定算法问题。     

网络安全技术在电子商务交易中的应用研究

着重分析了计算机网络安全问题及其产生的原因 ,针对电子商务交易过程中信息的动态性 ,深入探讨了防止动态攻击的技术 :加密技术和数字签名技术     

量子保密系统真随机源的实现

研究了基于物理随机源的方法产生真随机码：即用基于晶体二极管pn结齐纳击穿电压的随机性产生随机的电平信号,然后利用电压比较器甄别噪声电压,从而获得随机二进制序列,可用于控制量子保密通信系统的位相调制器,从而产生随机量子码。研制的随机二进制码理论上最大码率200kbit／s。     

Nonlinearity of Some Invariant Boolean Functions

One of the hardest problems in coding theory is to evaluate the covering radius of first order Reed–Muller codes RM(1,m), and more recently the balanced covering radius for crypto graphical purposes. The aim of this paper is to present some new results on this subject. We mainly study boolean functions invariant under the action of some finite groups, following the idea of Patterson and Wiedemann [The covering radius of the (1, 15) Reed-Muller Code is atleast 16276. IEEE Trans Inform Theory. Vol. 29 (1983) 354.]. Our method is Fourier transforms and our results are both theoretical and numerical.     

Elliptic Curve Cryptosystems in the Presence of Permanent and Transient Faults

Elliptic curve cryptosystems in the presence of faults were studied by Biehl et al., Advances in Cryptology CRYPTO 2000, Springer Verlag (2000) pp. 131–146. The first fault model they consider requires that the input point P in the computation of dP is chosen by the adversary. Their second and third fault models only require the knowledge of P. But these two latter models are less practical in the sense that they assume that only a few bits of error are inserted (typically exactly one bit is supposed to be disturbed) either into P just prior to the point multiplication or during the course of the computation in a chosen location.This paper relaxes these assumptions and shows how random (and thus unknown) errors in either coordinates of point P, in the elliptic curve parameters or in the field representation enable the (partial) recovery of multiplier d. Then, from multiple point multiplications, we explain how this can be turned into a total key recovery. Simple precautions to prevent the leakage of secrets are also discussed.communication by : P. WildThe work described in this paper has been supported [in part] by the Commission of the European Communities through the IST Programme under Contract IST-1999-12324, http://www.cryptonessie.org/. The information in this document is provided as is, and no guarantee or warranty is given or implied that the information is fit for any particular purpose. The user thereof uses the information at his sole risk and liability. The views expressed are those of the authors and do not represent an official view/position of the NESSIE project (as a whole)     

A Public Key Cryptosystem Based On A Subgroup Membership Problem

We present a novel public key encryption scheme semantically secure in the standard model under the intractability assumption of a subgroup membership problem related to the factorization problem.Parts of this paper have already been published by the authors [13]AMS classification: 94A60     

A Practical Protocol for Advantage Distillation and Information Reconciliation

Information-theoretic secret key agreement generally consists of three phases, namely, advantage distillation information reconciliation and privacy amplification. Advantage distillation is needed in the case when two legitimate users, Alice and Bob, start in a situation which is inferior to that of the adversary Eve. The aim for them is to gain advantage over Eve in terms of mutual information between each other. Information reconciliation enables Alice and Bob to arrive at a common string by error correction techniques. Finally they distill a highly secret string from the common string in the privacy amplification phase. For the scenario where Alice and Bob as well as Eve have access to the output of a binary symmetric source by means of (three) binary symmetric channels, there are several advantage distillation and information reconciliation protocols proposed.In this paper, we present a general protocol to implement both advantage distillation and information reconciliation. Simulation results are compared with known protocols. A connection between our protocol and the known protocols is given.     

Quantum Authentication Based on the Lengthened String Scheme

1　Introduction　Conventionallyhowtoachieveasecurekeyisthekeypointofacryptosystem ,andQuantumKeyDis tribution (QKD) providesawaytoachieveuncondi tionallysecurekey .Furthermore ,thesimulationofquantumkeydistributeononclassicalcomputershasbeendiscussedinRef.[1 ].Toguaranteethesecuri tyofthe quantumkeyinpracticalapplications,QuantumKeyAuthentication (QKA)isasimpor tantasQKD .ButtheconventionalQKD protocolssuchasBB84[2 ] ,B92 [3] ,andEPR[4] etc,havenotdonetheidentificationwork .Indeedin…