共查询到18条相似文献,搜索用时 890 毫秒
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有限域上的低差分一致性函数在密码学中有着重要的应用背景.目前人们发现的特征为2的有限域上的差分4一致函数并不是很多.通过交换定义在有限域F_2~n上的Kasami几乎完全非线性函数x~(2~(2k)—2~k+1)任意两点之间的取值,给出了一类新的差分4一致函数;并在n为奇数的情况下,证明了所给出的这类函数是具有较高非线性度和代数次数的置换函数. 相似文献
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有限域上的低差分一致性函数在密码学中有着重要的应用背景.目前人们发现的特征为2的有限域上的差分4一致函数并不是很多.通过交换定义在有限域F_2~n上的Kasami几乎完全非线性函数x^(2^(2k)—2~k+1)任意两点之间的取值,给出了一类新的差分4一致函数;并在n为奇数的情况下,证明了所给出的这类函数是具有较高非线性度和代数次数的置换函数. 相似文献
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分组峦码是现代密码学中一个重要的研究分支,而置换理论在分组密码中有重要的地位.199j年,美国Tcledyne电子技术公司的Lothrop Mittenthal博士提出了一种置换,即正形置换.止形置换是一类完全映射,完全映射是由Mann在1942年研究正交拉丁方的构造时引入的,其具有良好的密码学性质(良好的扩散性和完令平衡性),因此,正形置换常用来构造密码系统的算法,研究正形置换也就非常订必要.本文根据文章[1]的方法讨论了F2^n(n=4,5)上的4次正形置换多项式的形式与计数,至于n〉5的情形我们将在以后的篇章中继续讨论. 相似文献
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代数免疫度是针对代数攻击而提出来的一个新的密码学概念.要能够有效地抵抗代数攻击,密码系统中使用的布尔函数必须具有平衡性、较高的代数次数、较高的非线性度和较高的代数免疫度等.为了提高布尔函数的密码学性能,通过布尔函数仿射等价的方法,找出了所有具有最优代数免疫度的三变元布尔函数.由这些具有最优代数免疫度的三变元非线性布尔函数,递归构造了一类代数免疫度最优、代数次数较高的平衡布尔函数.给出了这类布尔函数非线性度的一个下界,偶数变元时,其下界严格大于Lobanov给出的下界. 相似文献
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关于二元四次样条插值与逼近 总被引:4,自引:0,他引:4
文[1]中讨论了上的插值问题,其中的插值函数表达式用到被插值函数的二阶导数.本文进一步研究空间上的一类新的二元样条插值形式,其中仅用到插值函数的一阶导数.证明了该插值形式的唯一性与存在性,且不需要解高维的线性方程组.最后给出了逼近度问题. 相似文献
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分组密码是现代密码学中一个重要的研究分支,而置换理论在分组密码中有重要的地位.1995年,美国Teledyne电子技术公司的Lothrop Mittenthal博士提出了一种置换,即正形置换.正形置换是一类完全映射,完全映射是由Mann在1942年研究正交拉丁方的构造时引入的,其具有良好的密码学性质(良好的扩散性和完全平衡性),因此,正形置换常用来构造密码系统的算法,研究正形置换也就非常有必要.本文根据文章[1]的方法讨论了F2n(n=4,5)上的4次正形置换多项式的形式与计数,至于n5的情形我们将在以后的篇章中继续讨论. 相似文献
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Bergman-Weil积分公式的拓广 总被引:1,自引:1,他引:0
林良裕 《数学物理学报(A辑)》1995,(4)
本文把Cn空间中著名的Bergman-Weil公式拓广到一类具有低维解析待征流形的微分多面体域上,从而获得在一类非解析的多面体域上建立具有全纯核的全纯函数的积分表示式. 相似文献
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Boolean functions with high nonlinearity and good autocorrelation properties play an important role in the design of block ciphers and stream ciphers. In this paper, we give a method to construct balanced Boolean functions of n variables, where n ≥ 10 is an even integer, satisfying strict avalanche criterion (SAC), and with high algebraic degree. Compared with the known balanced Boolean functions with SAC property, the constructed functions possess the highest nonlinearity and the best global avalanche characteristics property. 相似文献
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Propagation criteria and resiliency of vectorial Boolean functions are important
for cryptographic purpose (see [1–4, 7, 8, 10, 11, 16]). Kurosawa, Stoh [8] and Carlet [1]
gave a construction of Boolean functions satisfying PC(l) of order k from binary linear
or nonlinear codes. In this paper, the algebraic-geometric codes over GF(2m) are used to
modify the Carlet and Kurosawa-Satoh’s construction for giving vectorial resilient Boolean
functions satisfying PC(l) of order k criterion. This new construction is compared with
previously known results. 相似文献
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Let V be a finite-dimensional vector space over a finite field and let f be a trilinear alternating form over V. For such forms, we introduce two new invariants. Together with a generalized radical polynomial used for classification of forms in dimension 8 over GF(2), they are sufficient to distinguish between all trilinear alternating forms in dimension 9 over GF(2). To prove the completeness of the list of forms, we computed their groups of automorphisms. There are 31 degenerate and 317 nondegenerate forms. We point out some forms with either small or large automorphism group. 相似文献
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APN permutations in even dimension are vectorial Boolean functions that play a special role in the design of block ciphers. We study their properties, providing some general results and some applications to the low-dimension cases. In particular, we prove that none of their components can be quadratic. For an APN vectorial Boolean function (in even dimension) with all cubic components we prove the existence of a component having a large number of balanced derivatives. Using these restrictions, we obtain the first theoretical proof of the non-existence of APN permutations in dimension 4. Moreover, we derive some constraints on APN permutations in dimension 6. 相似文献
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Boolean functions with good cryptographic characteristics are needed for the design of robust pseudo-random generators for stream ciphers and of S-boxes for block ciphers. Very few general constructions of such cryptographic Boolean functions are known. The main ones correspond to concatenating affine or quadratic functions. We introduce a general construction corresponding to the concatenation of indicators of flats. We show that the functions it permits to design can present very good cryptographic characteristics. 相似文献
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T-functions have been widely used in the design of symmetric ciphers, hash functions, and fast cryptographic primitives. Single cycle polynomial T-functions are a special category. If they are used as state transition functions of stream ciphers, the security of the generated sequences is crucial. In 2008, Kolokotronis proposed a conjecture regarding the autocorrelation function’s values of coordinate sequences generated by single cycle polynomial T-functions. In this paper, we show that the conjecture does not hold in general and prove the conditions under which it holds. 相似文献
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Liu Jing-mei Wei Bao-dian Cheng Xiang-guo Wang Xin-mei 《Applied mathematics and computation》2005,170(2):213-975
By the discovered correlation between linear functions over GF(qn) and matrices over GF(q), a new scheme is presented to resolve the algebraic expression of Rijndael S-box in this paper. This new scheme has the advantage of predetermining in the case of a given random basis over GF(qn). The reason why only nine terms are involved in the algebraic expression of Rijndael S-box is presented, which corrects the available inaccurate illustration. An improved AES S-box is presented to improve the complexity of AES S-box algebraic expression with terms increasing from 9 to 255 and algebraic degree invariable. The improved AES S-box also has good properties of Boolean functions in SAC and balance, and is capable of attacking against differential cryptanalysis with high reliable security. We finally summarize all the available methods to determine the algebraic expression of Rijndael S-box. 相似文献
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Nonlinear filter generators are commonly used as keystream generators in stream ciphers. A nonlinear filter generator utilizes a nonlinear filtering function to combine the outputs of a linear feedback shift register (LFSR) to improve the linear complexity of keystream sequences. However, the LFSR-based stream ciphers are still potentially vulnerable to algebraic attacks that recover the key from some keystream bits. Although the known algebraic attacks only require polynomial time complexity of computations, all have their own constraints. This paper uses the linearization of nonlinear filter generators to cryptanalyze LFSR-based stream ciphers. Such a method works for any nonlinear filter generators. Viewing a nonlinear filter generator as a Boolean network that evolves as an automaton through Boolean functions, we first give its linearization representation. Compared to the linearization representation in Limniotis et al. (2008), this representation requires lower spatial complexity of computations in most cases. Based on the representation, the key recoverability is analyzed via the observability of Boolean networks. An algorithm for key recovery is given as well. Compared to the exhaustive search to recover the key, using this linearization representation requires lower time complexity of computations, though it leads to exponential time complexity. 相似文献