Security Analysis of Discrete Logarithm Based Cryptosystems

0 IntroductionNowthere are many well known cryptosystems based ondiscrete logarithms , such as the ElGamal cryptosys-tem[1]and the digital signature algorithm(DSA)[2]. Discretelogarithms have many advantages . Breaking the discrete log-arithm modulo pri mepappears to be somewhat harder thanfactoringintegern,and elliptic curve cryptosystems may usemuchsmaller keysizesthan RSA-basedcryptosystems of com-parable security.The discrete logarithmproblemover a group can be bro-ken down into a numb…     

密度演化方法在求解股市上扬天数中的应用

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板几何中一类具非对称散射裂变核的迁移算子的谱

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双参数量子代数SUqs（1,1）的表示：正离散序列

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一种改进的实信号IFFT算法

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Population biology of bryozoans: correlates of sessile,colonial life histories in freshwater habitats

Bryozoans are common, often abundant, sessile, colonial invertebrates of freshwaters. By reviewing what is known of their general ecology and considering in further detail the population biology of specific groups, we provide evidence that 1) populations are locally ephemeral and regional persistence is attained via a dynamic equilibrium between dispersal and colonization, and 2) sex may often be infrequent and a high degree of clonality obtains at both local and regional scales. On the basis of these characteristics we discuss how the group offers exceptional opportunities for investigating a number of fundamentally important ecological and evolutionary questions.The highly curious modification of the Molluscan type which the Polyzoa [=Bryozoa] present... the great beauty of their forms, and the facility with which they can in general be observed in a living state, cannot but render them special favorites for every lover of Nature; and for the more profound student must confer on them a peculiar significance, and invest their study with a scientific interest which is scarcely surpassed by that of any other group of animals.... (Allman 1856)     

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离散交换群上的万有Toeplitz算子代数

设G为一离散交换群,（G,G＋）为一拟偏序群．相应于这样的一个拟偏序群（G,G＋）,构造了一个万有Toeplitz算子代数．