共查询到19条相似文献,搜索用时 171 毫秒
1.
利用序列密码中的前馈模型设计了一个混沌序列密码算法,以线性反馈移位寄存器序列为初始序列,将Logistic映射和Chebyshev映射作为滤波函数,结合了压缩变换、SMS4算法的S盒变换、有记忆变换和移位变换。分析和实验结果证明算法具有足够的安全强度和较高的加密速度。 相似文献
2.
本文给出q元有限域上的反馈移位寄存器非奇异性判定的充分必要条件,并利用Groebner基理论对定理给出的条件进行约化,给出了q=3,4,5时任意次反馈函数非奇异性的充要条件. 相似文献
3.
针对序列密码中非线性布尔函数(NLBF)适配算法不具普遍性及资源消耗较多的问题,提出一种基于NLBF与项和真值表相结合的全局定向搜索算法。首先,通过NLBF中与项比率的分析,得出合理的查找表(LUT)适配形式;随后,提出布尔函数归类算法,归类算法从高次到低次搜索NLBF中全部与项,并对各与项进行“吸收”及“合并”处理;最后,提出基于真值表的配置信息生成算法,该算法通过遍历真值表的方式,生成LUT存储的配置信息以完成NLBF的运算。对序列密码进行适配发现,布尔函数归类算法能完成现有NLBF型序列密码的适配,且对常用的ACH-128、Trivium及Grain等算法更易适配;同时从对比结果可以看出,全局定向搜索算法的资源消耗较基于Shannon分解定理的适配算法及遗传算法明显要少;同时从资源消耗情况来看,4输入LUT消耗最多,6输入LUT消耗最少。 相似文献
4.
本文针对一类具有时变输出约束链式非完整系统的预设时间镇定问题,首先通过tan型障碍Lyapunov函数处理系统输出约束,然后基于所给的新型切换时变函数,直接应用于虚拟(实际)控制器设计,提出了系统状态反馈镇定的非缩放变换设计方案.本文所设计的控制器使得闭环系统状态不违反约束的同时,可在任意给定的有限时间内收敛到零点.与传统的基于缩放变换设计相比,本文所提出的控制策略既有效解决了控制器的计算奇异性问题,又减少了关于时变缩放函数的计算,使控制器设计更为简单.最后,通过仿真结果验证了所提设方法的有效性. 相似文献
5.
流密码算法Grain 的立方攻击 总被引:1,自引:1,他引:1
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(initial vector,简称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,则可恢复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,则可恢复1比特密钥. 相似文献
6.
7.
8.
基于正交小波变换的生产过程实时趋势分析 总被引:1,自引:0,他引:1
利用正交小波变换的时频分析及尺度特性,基于函数逼近及函数奇异性分析原理,提出了生产过程实时趋势分析算法,实例仿真研究证实了其可行性和有效性。 相似文献
9.
根据均热炉装钢的初值条件,基于模糊推理基本理论,获得温度控制的前馈量,构成知识库,利用迭代学习算法,修正前次迭代输入的前馈量。在烧钢加热过程中,采用前馈、反馈与迭代学习算法相结合的控制方案。 相似文献
10.
11.
A. O. Sulzberger 《Cryptologia》2013,37(1):51-53
Pless has proposed a stream cipher based on J-K flip-flops that uses 8 linear shift registers with feedback, having a combined length of 97 bits, 4 J-K flip-flops, and a 4-stage cycling counter. The cipher has 2.54×1051 initial states (keys), and generates a presumably pseudorandom stream whose period is 1.52×1029 bits. Despite these impressive statistics, it is computationally feasible to solve such a cipher with a known-plaintext attack, using as few as 15 characters. 相似文献
12.
Ali A. Kanso 《Computers & Electrical Engineering》2010,36(1):199-212
Encryption in wireless communication systems is an extremely important factor to protect information and prevent fraud. In this paper, we propose a new encryption system for use in stream cipher applications. The design proposed is intended for hardware implementation and based on (n+1) feedback shift registers interconnected in such a way that one register controls the clocking of the other n registers. The aim of this construction is to allow the production of a large family of distinct keystreams when the initial states and feedback functions of the feedback shift registers are unchanged. The produced keystreams are shown to possess the basic security requirements for cryptographic sequences such as long period, high linear complexity and good statistical properties, provided that suitable parameters are chosen. Furthermore, the design is shown to resist various types of cryptanalytic attacks. These characteristics and properties enhance its use as a suitable encryption system for stream cipher applications. 相似文献
13.
14.
Side-channel attacks on block ciphers and public key algorithms have been discussed extensively, but only a few systematic studies on the applicability of side-channel attacks to stream ciphers could be found. The objective of the present study is to develop general differential power analysis techniques which can be employed to attack the stream ciphers with linear feedback shift registers. To illustrate the new approach, a common structure of a stream cipher with the basic components is given. Then the approach is employed to analyze the given structure. The results show that the linear feedback shift registers may leak the information of the secret key. The approach is also applied to Crypto-1 and the experimental results show that it is very effective. 28-bit information of the 48-bit secret key can be obtained just by analyzing some power traces. Furthermore, the present work may be helpful in analyzing a variety of stream ciphers with LFSRs. 相似文献
15.
The NLM stream cipher designed by Hoon Jae Lee, Sang Min Sung, Hyeong Rag Kim is a strengthened version of the LM summation generator that combines linear and non-linear feedback shift registers. In recent works, the NLM cipher has been used for message authentication in lightweight communication over wireless sensor networks and for RFID authentication protocols. 相似文献
16.
Achterbahn is one of the candidate stream ciphers submitted to the eSTREAM, which is the ECRYPT Stream Cipher Project. The cipher Achterbahn uses a new structure which is based on several nonlinear feedback shift registers (NLFSR) and a nonlinear combining output Boolean function. This paper proposes distinguishing attacks on Achterbahn-Version 1 and -Version 2 on the reduced mode and the full mode. These distinguishing attacks are based on linear approximations of the output functions. On the basis of these linear approximations and the periods of the registers, parity checks with noticeable biases are found. Then distinguishing attacks can be achieved through these biased parity checks. As to Achterbahn-Version 1, three cases that the output function has three possibilities are analyzed. Achterbahn-Version 2, the modification version of Achterbahn-Version 1, is designed to avert attacks based on approximations of the output Boolean function. Our attack with even much lower complexities on Achterbahn-Version 2 shows that Achterbahn-Version 2 cannot prevent attacks based on linear approximations. 相似文献
17.
一种基于离散混沌系统的密钥流设计算法 总被引:4,自引:0,他引:4
本文设计了一种基于离散混沌系统的密钥流发生器算法.通过把简单混沌系统
与线性系统、分段线性状态反馈函数所形成的混沌系统在阈值化后进行异或运算,使得输出
的密钥流为不可预测性的伪随机序列.分析和仿真结果表明,本算法能有效地抵抗对系统的
预测攻击及统计分析,能够达到密码学上对密钥流的要求.该算法可作为流密码体制中的密
钥流发生器. 相似文献
18.
对新提议的一种基于线性反馈移位寄存器、非线性反馈移位寄存器和过滤布尔函数的序列密码结构的安全性进行了研究,对这种结构给出了一种区分攻击.举例子说明了此攻击的有效性.这种新的攻击表明,此种新的序列密码结构存在潜在的安全弱点. 相似文献