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本文解决了文献(5)提出了一个未决问题ψ(f,f^2,f,f,f)是超伪随机置换,证明了该置换能抵抗O(2^60)阶选择明文一密文攻击,并利用已证明的结果构造安全的消息认证码。 相似文献
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循环移位置换单元是准循环LDPC码的部分并行译码器的重要组成部分。该文研究并证明了Reverse Banyan交换结构在实现信息循环移位时各个基本交换单元的连接规律。基于该规律设计了基于可预置选路算法的无阻塞循环移位置换结构。相比Benes交换结构和Reverse Banyan交换结构,提高了信息循环移位交换的速率,且占用较少的硬件资源和面积。最后设计了一个出线转换单元,该单元适用于各种循环移位交换结构。 相似文献
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该文深入研究了Lai-Massey结构的伪随机特性。首先,证明了基于仿射几乎正形置换设计的3轮Lai- Massey模型并不具有伪随机特性,给出了Lai-Massey结构设计者所得结论的一个反例。其次,证明了双射为任意正形置换时,至少3轮Lai-Massey结构才具有伪随机特性;证明了双射为仿射正形置换时,至少4轮的Lai-Massey结构才具有超伪随机特性。结论表明,为构造伪随机特性更好的Lai-Massey结构实例,双射最好设计为非线性的正形置换或几乎正形置换。 相似文献
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随机数在信息安全中起着非常重要的作用。对基于线性反馈移位寄存器的两类随机数生成算法进行了研究,发现这两类算法生成的随机数具有很好的随机性,但其安全性没有考虑。在此基础上,结合线性反馈移位寄存器与高级加密标准(AES, Advanced Encryption Standard),提出了一种产生伪随机数的算法,并对新算法的安全性和随机性进行了分析。分析发现新算法所产生的随机数具有很好的随机性,其安全性依赖于AES的安全性。 相似文献
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为产生随机性能良好的伪随机序列,提出了一个新的变结构混沌系统。该混沌系统在一个开关函数控制下其系统结构随时间随机地转换,所产生的混沌信号是两个不同的混沌信号的混合,具有良好的复杂性。基于该变结构混沌系统设计了一种伪随机序列发生器,采用NIST标准和STS-2.0b测试套件对其产生的伪随机序列进行了统计性能测试,测试结果表明该伪随机序列发生器具有良好的随机性,可应用于计算机、通信、信息加密等领域中。 相似文献
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一种基于循环移位矩阵的LDPC码构造方法 总被引:3,自引:0,他引:3
具有准循环结构的低密度奇偶校验码(QC-LDPC Codes)是目前被广泛采用的一类LDPC码。本文提出了一种结合PEG算法构造基于循环移位矩阵的QC-LDPC码的方法。该方法首先将QC-LDPC码传统的基于比特的二分图简化为基于Block的二分图,然后在该图中采用PEG算法遵循的环路最大原则确定每一个循环移位矩阵的位置,最后根据QC-LDPC码的环路特性为每一个循环移位矩阵挑选循环移位偏移量。利用该算法,本文构造了长度从1008bit到8064bit,码率从1/2到7/8各种参数的LDPC码。仿真结果表明,本文构造的LDPC码性能优于目前采用有限几何、两个信息符号的RS码、组合数学等常用的代数方法构造的QC-LDPC码。 相似文献
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基于移位矩阵优化的LDPC码构造 总被引:2,自引:0,他引:2
环的存在对准循环LDPC(Low Density Parity Code)码的译码效率造成很大影响,拥有尽可能好的girth分布的校验矩阵对于码的性能改善有着重要的意义。首先对准循环LDPC码校验矩阵的girth分布进行分析,然后在母矩阵和移位矩阵之间设定一个合理的约束关系,使得构造后的校验矩阵最小环长及平均最小环长追求最大化,最后提出了一种易于实现的具有高girth的QC-LDPC(Quasi cyclic-Low Density Parity Code)码构造方法。仿真结果表明,该方法尽量减少码中的短循环,能构造实用化的好码。 相似文献
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In cryptographic protocols it is often necessary to verify/certify the tools in use. This work demonstrates certain subtleties in treating a family of trapdoor permutations in this context, noting the necessity to check certain properties of these functions. The particular case we illustrate is that of noninteractive zero-knowledge. We point out that the elegant recent protocol of Feige, Lapidot, and Shamir for proving NP statements in noninteractive zero-knowledge requires an additional certification of the underlying trapdoor permutation, and suggest a method for certifying permutations which fills this gap.A preliminary version of this paper appeared in Advances in Cryptology—Crypto 92 Proceedings, Lecture Notes in Computer Science, Vol. 740, E. Brickell, ed., Springer-Verlag, Berlin, 1992. This work was done while Mihir Bellare was at the IBM T.J. Watson Research Center, Yorktown Heights, NY. 相似文献
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时控性加密(TRE)是一种被称为“向未来发送消息”的密码原语,接收方在未来指定时间之前无法解密密文。目前,大部分TRE方案采用非交互式单时间服务器方法,系统用户能够正常解密,依赖于单一时间服务器在预定解密时间计算并广播的时间陷门。如果单一的时间服务器遭受攻击,或被腐败,则容易直接威胁TRE的安全应用。因此,需要将1个时间服务器“分散”成多个。但已有多时间服务器TRE方案既没有给出安全性分析,也没有给出严格的安全性证明。为此,该文给出一种随机预言机模型下基于双线性迪菲·赫尔曼(BDH)问题的多时间服务器的TRE模型MTSTRE,构造出一种可证明安全的具体和通用方案,并严格证明所提具体方案在自适应选择明文攻击下是安全的。效率分析表明,与已有最有效的多时间服务器TRE解决方案相比,所提具体方案的计算效率也略有提高。 相似文献
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We know that trapdoor permutations can be used to construct all
kinds of basic cryptographic primitives, including trapdoor
functions, public-key encryption, private information retrieval,
oblivious transfer, key agreement, and those known to be
equivalent to one-way functions such as digital signature,
private-key encryption, bit commitment, pseudo-random generator
and pseudo-random functions. On the other hand, trapdoor functions
are not as powerful as trapdoor permutations, so the structural
property of permutations seems to be something special that
deserves a more careful study. In this paper we investigate the
relationships between one-way permutations and all these basic
cryptographic primitives. Following previous works, we focus on an
important type of reductions called black-box reductions. We prove
that no such reductions exist from one-way permutations to either
trapdoor functions or private information retrieval. Together with
previous results, all the relationships with one-way permutations
have now been established, and we know that no such reductions
exist from one-way permutations to any of these primitives except
trapdoor permutations. This may have the following meaning, with
respect to black-box reductions. We know that one-way permutations
imply none of the primitives in "public cryptography," where
additional properties are required on top of "one-wayness"
\cite{IR89}, so permutations cannot be traded for any of these
additional properties. On the other hand, we now know that none of
these additional properties can be traded for permutations either.
Thus, being a permutation seems to be something orthogonal to
those additional properties on top of one-wayness. Like previous
non-reducibility results, our proofs follow the oracle separation paradigm of Impagliazzo and
Rudich. 相似文献
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为了消除逆合成孔径雷达(ISAR)越分辨单元徙动(MTRC)引起的图像散焦,需要估计目标的等效旋转中心。该文以空间目标为研究对象,提出了一种基于图像旋转相关的ISAR旋转中心估计算法。首先,分析了ISAR的瞬时成像机理;其次,将采用相同运动补偿后的回波数据分段成像,得到不同视角的2幅图像;然后,基于定标后的图像像素旋转和图像相关,估计等效旋转中心。当假定的等效旋转中心与真实的旋转中心一致时,2幅图像相关性最大,据此得到旋转中心位置。仿真实验表明,该算法能够有效利用图像整体信息,估计出高精度的目标等效旋转中心,利于提高成像质量。 相似文献
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Construction and count of 1-resilient Rotation symmetric Boolean functions (RSBFs) on pr variables are demonstrated. It is proved that constructions of 1-resilient RSBFs on pr variables are equivalent to solving an equation system. An accurate enumeration formula of all 1-resilient RSBFs on pr variables is also proposed. Some examples are given, and the exact numbers of 1-resilient RSBFs on 8 and 9 variables are obtained respectively. 相似文献
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《电子学报:英文版》2017,(6):1276-1283
This paper studies the properties of orbit matrix and gives a formula to compute the number of these orbit matrices on 4p variables, where p is an odd prime. It has been demonstrated that the construction of 1-resilient Rotation symmetric Boolean functions (RSBFs) on 4p variables is equivalent to solving an equation system. By the proposed method, all 1-resilient RSBFs on 12 variables can be constructed. We present a counting formula for the total number of all 1-resilient RSBFs on 4p variables. As application of our method, some 1-resilient RSBFs on 12 variables are presented. 相似文献
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Luby and Rackoff [26] showed a method for constructing a pseudorandom permutation from a pseudorandom function. The method
is based on composing four (or three for weakened security) so-called Feistel permutations, each of which requires the evaluation
of a pseudorandom function. We reduce somewhat the complexity of the construction and simplify its proof of security by showing
that two Feistel permutations are sufficient together with initial and final pairwise independent permutations. The revised
construction and proof provide a framework in which similar constructions may be brought up and their security can be easily
proved. We demonstrate this by presenting some additional adjustments of the construction that achieve the following:
• Reduce the success probability of the adversary.
• Provide a construction of pseudorandom permutations with large input-length using pseudorandom functions with small input-length.
Received 2 August 1996 and revised 26 July 1997 相似文献