共查询到19条相似文献,搜索用时 187 毫秒
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该文构造了具有2k个起始点的变长"钻石树"结构的多碰撞,并据此提出了对强化MD结构杂凑函数的一个新的选择目标强制前缀且原像长度为2k+3块的原像攻击(即"牧群"攻击).由于增大了攻击过程中可利用的中间链接值的数量,故当k≤n/4-1.05时,新的牧群攻击可将该攻击的计算复杂性由现有结果O(2n-2(k+1)+2n/2+k+5+2)降至O(2n-k/3+2n/2+k+2). 相似文献
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基于中间相遇攻击技术,提出了一种针对密码杂凑函数SM算法的原根攻击和伪碰撞攻击方法,给出了从第1步开始的带消息填充的29步SM3算法的原根攻击和伪碰撞攻击。结果表明:对于29步SM3算法的原根攻击的时间复杂度为2254;对于29步SM3伪碰撞攻击的时间复杂度为2125。说明从第1步开始的带消息填充的29步SM3算法不能抵抗原根攻击和伪碰撞攻击。 相似文献
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提出一种改进的基于杂凑函数的RFID标签数据的安全认证算法.该算法采用RFID标签和读写器的双向认证机制,并利用BAN逻辑对其进行形式化分析,结果表明该算法具有前行安全性、重传攻击、哄骗攻击、位置跟踪、不可分辨性等特点,能够较好的解决RFID标签数据的安全隐患问题. 相似文献
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在分析扩展整数帐篷映射均匀分布特性的基础上,提出一种输出长度为160bit的动态散列函数构造方案.另外,对MD结构进行了改进,在无需扩展中间状态的情况下,提高了散列函数抵抗部分消息碰撞攻击的能力.初步的安全性测试表明,这种散列函数具有很强的安全性,且实现简单、运行速度快,是传统散列函数的一种理想的替代算法. 相似文献
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Hash函数,或者称为密码学Hash函数,是密码学应用的重要组成部分.Hash函数由于其压缩特性,常常被用做消息的核实和认证.近年来,各种基于密码学Hash函数的攻击方式被广泛发现.在这些攻击中不但包含了针对MD4,MD5的攻击还包含了针对其它MD家族Hash函数的攻击.本文从密码分析学的角度讨论了安全Hash函数的构成和它们在消息认证码(MAC)中的应用.并进一步讨论了其当前的研究状况,简要分析了针对MD家族Hash函数密码分析学的进展. 相似文献
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已有光纤传感大数据异常监测系统由于数据异常检测响应过慢,导致数据异常预警延迟时间过长,无法满足现今社会生产需求,因此提出了基于密码杂凑函数的光纤传感大数据异常监测方法.引入密码杂凑函数设计光纤传感大数据异常监测系统,其硬件单元包括光传感单元、系统控制单元与数据采集单元;软件模块包括光纤传感大数据采集模块、光纤传感大数据... 相似文献
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A preimage attack on 32-step SM3 hash function and a pseudo-collision attack on 33-step SM3 hash function respectively were shown.32-step preimage attack was based on the differential meet-in-the-middle and biclique technique,while the previously known best preimage attack on SM3 was only 30-step.The 33-step pseudo-collision attack was constructed by using the same techniques.The preimage attack on 32-step SM3 can be computed with a complexity of 2254.5,and a memory of 25.Furthermore,The pseudo-preimage and pseudo-collision attacks on 33-step SM3 by extending the differential characteristic of the 32-step preimage attack were present.The pseudo-collision attack on 33-step SM3 can be computed with a complexity of 2126.7,and a memory of 23. 相似文献
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Generalized Kasami Sequences: The Large Set 总被引:2,自引:0,他引:2
Xiangyong Zeng Liu J.Q. Lei Hu 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(7):2587-2598
In this correspondence, new binary sequence families Fk of period 2n-1 are constructed for even n and any k with gcd(k,n)=2 if n/2 is odd or gcd(k,n)=1 if n/2 is even. The distribution of their correlation values is completely determined. These families have maximum correlation 2n/2+1 and family size 23n/2 + 2n/2 for odd n/2 or 23n/2+2n/2-1 for even n/2. The proposed families include the large set of Kasami sequences, where the k is taken as k=n/2+1. 相似文献
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Etzion T. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1999,45(2):693-698
The linear complexity of a de Bruijn sequence is the degree of the shortest linear recursion which generates the sequence. It is well known that the complexity of a binary de Bruijn sequence of length 2n is bounded below by 2n-1+n and above by 2n-1 for n⩾3. We briefly survey the known knowledge in this area. Some new results are also presented, in particular, it is shown that for each interval of length 2[log n]+1 in the above range, there exist binary de Bruijn sequences of length 2n with linear complexity in the interval 相似文献
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In this brief, the design of residue number system (RNS) to binary converters for a new powers-of-two related three-moduli set {2n+1 - 1, 2n, 2n - 1} is considered. This moduli set uses moduli of uniform word length (n to n + 1 bits). It is derived from a previously investigated four-moduli set {2n - 1, 2n, 2n + 1, 2n +1 - 1}. Three RNS-to-binary converters are proposed for this moduli set: one using mixed radix conversion and the other two using Chinese remainder theorem. Detailed architectures of the three converters as well as comparison with some earlier proposed converters for three-moduli sets with uniform word length and the four-moduli set {2n - 1, 2n, 2n + 1, 2n+1 - 1} are presented. 相似文献
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Mohan P.V.A. Premkumar A.B. 《IEEE transactions on circuits and systems. I, Regular papers》2007,54(6):1245-1254
In this paper, reverse converters for two recently proposed four-moduli sets {2n - 1,2n,2n + 1,2n+1 - 1} and {2n - 1, 2n, 2n + 1, 2n+1 + 1} are described. The reverse conversion in the three-moduli set {2n - 1,2n,2n + 1} has been optimized in literature. Hence, the proposed converters are based on two new moduli sets {(2n(22n-1)),2n+1-1} and {(2n(22n-1)), 2n+1+1} and use mixed radix conversion. The resulting designs do not require any ROM. Both are similar in their architecture except that the converter for the moduli set {2n - 1, 2n, 2n + 1, 2n+1 + 1} is slightly complicated due to the difficulty in performing reduction modulo (2n+1+1) as compared with modulo (2n+1-1). The proposed conversion techniques are compared with earlier realizations described in literature with regard to conversion time as well as area requirements. 相似文献
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The residue number system (RNS) appropriate for implementing fast digital signal processors since it can support parallel, carry-free, high-speed arithmetic. A development in residue arithmetic is the quadratic residue number system (QRNS), which can perform complex multiplications with only two integer multiplications instead of four. An RNS/QRNS is defined by a set of relatively prime integers, called the moduli set, where the choice of this set is one of the most important design considerations for RNS/QRNS systems. In order to maintain simple QRNS arithmetic, moduli sets with numbers of forms 2n+1 (n is even) have been considered. An efficient such set is the three-moduli set (22k-2+1.22k+1.22k+2+1) for odd k. However, if large dynamic ranges are desirable, QRNS systems with more than three relatively prime moduli must be considered. It is shown that if a QRNS set consists of more than four relatively prime moduli of forms 2n+1, the moduli selection process becomes inflexible and the arithmetic gets very unbalanced. The above problem can be solved if nonrelatively prime moduli are used. New multimoduli QRNS systems are presented that are based on nonrelatively prime moduli of forms 2n +1 (n even). The new systems allow flexible moduli selection process, very balanced arithmetic, and are appropriate for large dynamic ranges. For a given dynamic range, these new systems exhibit better speed performance than that of the three-moduli QRNS system 相似文献
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Kato A. Zeger K. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1999,45(5):1527-1540
Two-dimensional binary patterns that satisfy one-dimensional (d, k) run-length constraints both horizontally and vertically are considered. For a given d and k, the capacity Cd,k is defined as Cd,k=limm,n→∞log2Nm,n d,k/mn, where Nm,nd,k denotes the number of m×n rectangular patterns that satisfy the two-dimensional (d,k) run-length constraint. Bounds on Cd,k are given and it is proven for every d⩾1 and every k>d that Cd,k=0 if and only if k=d+1. Encoding algorithms are also discussed 相似文献
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Grid security infrastructure (GSI) provides the security in grids by using proxy certificates to delegate the work of authentication. At present, revocation proxy certificate has two kinds of methods, one is using certificate revocation list (CRL) and the other is giving the certificate a short period of validity. However, when a lot of certifications are revoked, CRL will be the burden in the system. If the certificate has a short period of validity, entities should be often updating the certificate. In this paper, we propose a scheme for proxy certificate revocation using hash tree. Our scheme only needs hash value comparisons to achieve the purpose of certificate revocation. Previous two methods have to wait the expiration of the certificate. Therefore, our scheme is more flexible than previous methods. 相似文献