on the linear complexity of output sequences of single-cycle t-function

单圈T函数可以作为LFSR(linear feedback shift register)的代替组件用来设计序列密码,这样的序列密码算法在软件上具有很好的运行效率.研究了单圈T函数输出序列的线性复杂度等密码学性质.给出了当n为一般情况时,单圈T函数输出序列的线性复杂度,以及相应的极小多项式.国家自然科学基金(60833008,60902024)资助The single-cycle T-functions can be used as substitute for LFSR(linear feedback shift register) in stream ciphers,and such stream ciphers are very efficient in software.We have studied some cryptographic properties of single-cycle T-functions.We present the linear complexity and the minimal polynomial of the output sequences of single-cycle T-functions when n is an arbitrary positive integer

construction and selection scheme of seeded-key database of collisionfree cpk

组合公钥CPK(Combined Public Key)是我国拥有完全知识产权的认证技术,与PKI和IBC相比有其独特的优势。但由于密钥由种子密钥经过组合运算生成,因此可能发生碰撞,有效解决碰撞问题已成为CPK体制发展和完善的关键。介绍了CPK的发展、研究现状和存在问题;根据其构建特点,提出了两种新的种子公/私钥组合选取方法,使得在相同规模的安全需求下,所需种子公/私钥量大大减少;针对产生碰撞的两种可能因素提出了解决方案:用分组密码对用户标识进行映射、按照特定规则产生种子公/私钥库以及对椭圆曲线参数进行约束,从根本上消除了碰撞。优化后的CPK体制,无碰撞,种子库规模小,构建效率高,占用空间少,安全性高,可靠性强,便于管理。Combined Public Key(CPK)is an authentication technique which is an independent intellectual property of China.Compared with PKI and IBC,CPK has its particular advantages.However,since the secret key is generated by combining several seeded secret keys,collisions might happen.How to avoid collisions efficiently becomes the linchpin of the development of CPK.After the development and problems of CPK are introduced,two novel methods are put forward to select and combine the seeded public/private keys,which reduces the seeds space evidently with the same level of security.A solution is proposed aiming at two factors which lead to collisions:using block ciphers to map the user identity,produce seeds in accordance with specific rules and restrict the parameters of elliptic curve.The improved CPK system can provide a collision-free key space with a smaller space of seeds,high efficiency,high security,and easy management

Covariance Based Learning Algorithm for Gaussian Mixture Model

对混合高斯模型参数估计问题的算法通常是基于期望最大(Expectation Maximization)给出的.在混合高斯模型的因素协方差矩阵已知、因素各分量独立的前提下,给出了基于协方差矩阵的机器学习算法,简称CVB(Covari-ance Based)算法,并进行了一定的数学分析.最后给出了与期望最大算法的实验结果比较.实验结果表明,在该条件下,基于协方差的算法优于期望最大算法

Secret level valuation method of BLP model based on some application properties

根据信息系统的主客体访问属性规律，给出了一种可行的BLP模型密级赋值方法，提出了2个归并条件。继而给出了归并后的BLP模型下的主客体密级赋值的数学模型。证明了当条件解是非常值赋值解时，其扩张还原解不一定是全局解的结果，但由该解可以得到全局解的近似条件修改赋值解。利用近似条件修改赋值解，给出了某国家级信息系统BLP模型的密级具体赋值，解决了应用中的实际困难问题。 According to the access attribute properties between subjects and objects in the information system, a viable method of the BLP model secret level valuation was given, and two merging conditions were put forward. The mathe-matical model of subject-object secret level valuation under BLP model was established on the two merging conditions. When the condition solution was not the constant one, its expansion solution being not sure the global one was proved, but the approximate condition modification valuation solution could be obtained from it. Using the above results, one dif-ficult problem from one national information system about the BLP model secret level valuation was solved.According to the access attribute properties between subjects and objects in the information system, a viable method of the BLP model secret level valuation was given, and two merging conditions were put forward. The mathe-matical model of subject-object secret level valuation under BLP model was established on the two merging conditions. When the condition solution was not the constant one, its expansion solution being not sure the global one was proved, but the approximate condition modification valuation solution could be obtained from it. Using the above results, one dif-ficult problem from one national information system about the BLP model secret level valuation was solved

analysis of the success probability of cube attack

在一般随机布尔函数及布尔函数的代数次数或代数标准型项数受限情况下,从理论上分析了立方攻击的成功概率,对立方攻击密码分析方法提供了理论支持。理论结果与对流密码算法Trivium及Grain v1的实验结果是相吻合的。国家自然科学基金资助项目(60833008,60902024)The success probability of cube attack was theoretically discussed when a boolean function was chosen at random and the algebraic degree or the number of terms in its algebraic normal form representation was restricted.The results provided theoretic support to cube attack.The theoretical results meet with the experimental results of the analysis of the stream ciphers Trivium and Grain v1 very closely

national security vulnerability database classification based on an lda topic model

采用隐含Dirichlet分布主题模型(latent Dirichletallocation,LDA)和支持向量机(support vector machine,SVM)相结合的方法,在主题向量空间构建一个自动漏洞分类器。以中国国家信息安全漏洞库(CNNVD)中漏洞记录为实验数据。实验表明:基于主题向量构建的分类器的分类准确度比直接使用词汇向量构建的分类器有8%的提高。国家重点科技专题“核高基”资助项目(2010ZX01036-001-002)The current vulnerabilities in China are analyzed using a dataset from the China National Vulnerability Database of Information Security (CNNVD), with a combined latent Dirichlet allocation (LDA) topic model and a support vector machine (SVM) to construct a classifier in the topic vector space. Tests show that the classifier based on topic vectors has about 8% better classification performance than that based on text vectors

Formal analysis of power separation mechanism based on Biba model

　　强制访问控制是建设高级别安全信息系统的必要条件。本文基于Biba模型，重点给出了信息系统中系统管理员、安全管理员和安全审计员三权分立的形式化分析。通过分析，给出三权分立管理机制下，保障信息系统安全管理的条件。本文的结果在某国家级信息系统的具体建设中得到了应用。Mandatory access control is a necessary condition for constructing a high level of security information system. In this paper, based on Biba model, we give formal analysis for power separation mechanism under the condition which administrators are divided into system administrators, security administrators and security auditors, through the analysis, we give the conditions of guaranteeing the security of the information system management under separation of the three powers management mechanism. The results of this paper have been applied to the construction of a national information system

Study on the Random Numbers Generated by the Ancient Divination

随机数在现代科学中有着重要应用,随机数隶属可测函数范畴,因此随机数历.史是数学史的重要组成部分.追朔随机数的历史,可以在《易经》中的《系辞传》中发现筮法.筮法是古代中国产生随机数的方法.筮法过程可以看作为带外来输入的随机过程,也就是说筮法是数学史中的随机过程的古代中国实例.在严格的概率论模型的基础上,给出了筮法所产生的随机数概率,并给出了其信息熵.结果修改了向传三的结果.Random numbers in modern science have important applications. Random numbers belong to the measurable function field, so the random number history is an important part of the history of mathematics. In the "I Ching", the ancient divination was one kind of methods to generate random numbers. Divination process is a random process with external input. Based on the strict probability model of the divination, this paper gives the divination probability, and modification of results of Xiang Chuansan

cube attack on grain

Dinur和Shamir在2009年欧洲密码年会上提出了立方攻击的密码分析方法.Grain算法是欧洲序列密码工程eSTREAM最终入选的3个面向 硬件实现的流密码算法之一,该算法密钥长度为80比特,初始向量(IV)长度为64比特,算法分为初始化过程和密钥流产生过程,初始化过程空跑160拍. 利用立方攻击方法对Grain算法进行了分析,在选择IV攻击条件下,若算法初始化过程空跑70拍,我们可恢复15比特密钥,并找到了关于另外23比特密 钥的4个线性表达式;若算法初始化过程空跑75拍,我们可恢复1比特密钥.At EUROCRYPT 2009, Dinur and Shamir proposed a new type of algebraic attacks named cube attack. Grain is one of the 3 final hardware-oriented stream ciphers in the eSTREAM portfolio, which takes as input an 80-bit secret key and a 64-bit initial vector, and produces its keystream after 160 rounds of initialization. Applying cube attack on Grain with 70 initialization rounds, we can recover 15-bit secret key and find 4 linear equations on another 23 bits of the secret key. Moreover, applying cube attack on Grain with 75 initialization rounds, we can recover 1-bit secret key

cryptographic properties of bomm

BOMM(byte-oriented memorial mixer)算法是一种基于字节操作的混合型带记忆的序列扰乱算法,因具备良好的密码学性质,一个新的流密码算法Loiss使用了它作为主要组件.建立了BOMM算法的5次代数方程系统,在此基础上讨论了针对Loiss算法的代数攻击的复杂度.此外还发现了BOMM算法的一个统计弱点,并分析了Loiss算法在一类弱密钥下的安全性.BOMM is a byte-oriented mixed type algorithm with memory,which is used to disorder a given byte sequence.It has been used as a main component in a new stream cipher called Loiss for having many good cryptographic properties.This paper builds an algebraic equation system with degree 5 for BOMM,and based on this equation system,discusses the complexity of algebraic attack on Loiss.In addition,the paper also discusses the statistic weakness of BOMM and gives an analysis of the security of Loiss under a specific class of weak keys