基于最优区分器的多差分密码分析方法

如何利用多个差分特征对分组密码算法进行差分攻击,从而精确地估计出分组密码算法抵抗差分攻击的能力,是一个重要的研究课题.文中基于最优区分器的思想,提出了一种多差分密码分析方法.针对每个实验密钥,构造出基于多个差分特征的统计量,根据统计量的大小判决实验密钥是否为正确密钥.给出了多差分分析方法的计算复杂度,分析了正确密钥、错误密钥对应统计量的概率分布规律,并在此基础上给出了多差分分析方法的成功率和数据复杂度之间的关系.通过具体实例表明,在成功率相同的条件下,基于的差分特征越多,需要的数据复杂度越小.

基于卡方统计量的多差分攻击方法

为了精确地估计分组密码算法抵抗差分攻击的能力,在已知多个具有高概率差分特征的条件下,提出了基于卡方统计量的多差分攻击方法.分析了正确密钥和错误密钥对应的统计量的分布规律,给出了多差分攻击方法的成功率、数据复杂度和计算复杂度的关系.在分组密码算法的差分特征概率未知的条件下,该方法仍然是适用的.

对21轮SMS4算法的多差分攻击

SMS4算法一种是用于WAPI的分组密码算法,也是国内官方公布的第一个商用密码算法,该算法公布后即引起国内外密码学界的分析热潮.SMS4算法的分组长度为128比特,密钥长度为128比特,加密算法与密钥扩展算法都采用32轮迭代结构.本文的分析方法是综合利用了2^(28)个17轮的SMS4的差分特征,采用基于最优区分器思想的多差分攻击方法对21轮的SMS4算法进行攻击和分析,针对每个实验密钥,构造出基于多个差分特征的统计量,根据统计量的大小判决实验密钥是否是正确密钥.给出了多差分分析方法的计算复杂度,分析了正确密钥、错误密钥对应统计量的概率分布规律,在此基础上给出了多差分分析方法的成功率和数据复杂度之间的关系.最终得出结论可以2^(104)的数据复杂度,2^(114)的计算复杂度,来恢复出该算法的128比特圈子密钥.用该结果与目前已知的对21轮SMS4算法的差分攻击结果进行对比我们可以看出,攻击的数据复杂度和计算复杂度都有所降低.基于该研究结果,我们可以得出以下结论,在成功率相同的条件下,基于的差分特征越多,需要的数据复杂度和计算复杂度越小.

基于深度学习的多差分神经网络区分器及其应用

随着深度学习的发展,尤其是随着多层神经网络(MLP)、深度神经网络(DNN)、卷积神经网络(CNN)等网络的出现,其在多个领域得到广泛应用,如视觉识别、语音识别、自然语言处理等领域。在2019年的美密会上提出利用单差分深度残差网络区分器进行密钥恢复攻击的方法,将深度学习的应用扩展到密码算法分析领域。利用多差分残差网络区分器进行密钥恢复攻击,该方法可有效减少数据复杂度,并增加攻击轮数。以RC516的攻击为例,计算复杂度和数据复杂度分别减少为后者的1/12,攻击轮数由11个半轮增加到了12个半轮。

具有Pbest引导机制的适应性多策略差分进化算法

为进一步提升差分进化算法的收敛性能,提出一种具有Pbest引导机制的适应性多策略差分进化算法(AMSDE).AMSDE设计交叉概率控制参数库、变异尺度参数库及差分变异策略库,其中,交叉概率采用Logistic混沌序列来模拟,尺度参数采用线性变化机制产生,差分变异策略库采用6个常用的差分变异策略组成,并给出算法运行的框架.最后,基于25个标准测试函数的仿真结果表明,AMSDE的收敛性能优于现存的其它差分进化算法,具有较好的收敛精度及收敛速度.

对SMS4密码算法改进的差分攻击

差分分析和线性分析是重要的密码算法分析工具.多年来,很多研究者致力于改善这两种攻击方法.Achiya Bar-On等人提出了一种方法,能够使攻击者对部分状态参与非线性变换的SPN结构的密码算法进行更多轮数的差分分析和线性分析.这种方法使用了两个辅助矩阵,其目的就是更多地利用密码算法中线性层的约束,从而能攻击更多轮数.将这种方法应用到中国密码算法SMS4的多差分攻击中,获得了一个比现有攻击存储复杂度更低和数据复杂度更少的攻击结果.在成功概率为0.9时,实施23轮的SMS4密钥恢复攻击需要2^(113.5)个明文,时间复杂度为2^(126.7)轮等价的23轮加密.这是目前为止存储复杂度最低的攻击,存储复杂度为2^(17)个字节.

对16轮PRESENT算法差分分析的改进

PRESENT算法是一个SPN结构的轻量级分组密码算法,适用于计算资源有限的环境与设备.差分分析是攻击分组密码最为基本和有效的方法之一,对于迭代31轮的PRESENT算法,目前最好的差分分析结果是16轮,使用明文全空间2^(64)个选择明文.本文在原有差分分析结果的基础上,根据线性P置换的扩散性质,得出在相邻两轮中活动S盒的数目与S盒差分值的汉明重量之间的关系.搜索差分路径时取不同位置的活动S盒,比较6轮差分路径的结果,在得到最多结果的位置上寻找14轮概率为2^(-62)的差分路径,从解密方向找到119个,从加密方向找到28个.在成功率为99%的情况下,将16轮多差分输入值-单差分输出值分析结果的数据量由原来的2^(64)个选择明文降低到2^(59.16)个,时间复杂度由原来的2^(64)次内存访问降低到2^(59.16)次,存储复杂度由原来的2^(32)个6比特计数器降低到2^(32)个3比特计数器.同时给出单差分输入值-多差分输出值的差分分析结果,数据量为2^(61.16)个选择密文,时间复杂度为2^(61.16)次内存访问,存储复杂度为2^(32)个4比特计数器.

基于深度学习的差分神经区分器求解方法

针对差分神经区分器中准确率随着密码算法轮数增加而快速降低的问题,提出一种差分神经区分器求解方法。将深度学习技术与多差分密码分析相结合,通过采用神经网络拟合密码算法的多输入及多输出差分,设计多差分神经区分器通用模型。该模型中所使用的输入参数被设置为多个明文差分、相应的密文及密文差分。将其应用于分析Speck32/64及Simon32/64密码算法,结果表明,Speck32/64的5至7轮区分器准确率均有显著提升;Simon32/64的密码区分器轮数从9轮提升至10轮,说明该方法的有效性。

Empowerment Mechanisms and Empirical Evidence of Payment Technology in Capacity Expansion and Quality Improvement of Residents’Consumption

The time-varying difference-in-difference model is used to identify the impact of payment technology on residents’consumption,and the moderation effect analysis method is used to identify its mechanism.It is found that payment technology promotes consumption capacity expansion and quality improvement(CEQI)through three pathways of alleviating liquidity constraints,reducing transaction costs and weakening the payment of pain.The parallel and serial mechanisms of the three are further explored.The effect of payment technology on the CEQI of residents’consumption shows obvious heterogeneity due to differences in urban and rural household registration and financial literacy.Based on the empirical research results and the national conditions of China,targeted policy recommendations are proposed from the demand side,the supply side and the technological side.

Schrdinger方程的一个显格式

本文构造了一个解ＳｃｈｒＯ¨ｄｉｎｇｅｒ方程的三层显式差分格式，格式绝对稳定，截断误差为Ｏ（τ２＋ｈ２）．

Research of the wave measurement using GPS absolute velocity estimation technology

This paper analyzed the existing methods of wave measurement, and described the advantages of GPS applied in measuring the wave. The equations of absolute velocity estimation were discussed, focusing on two methods with Doppler shill. The error sources and their effect on velocity estimation were analyzed. Then, some tests were carried on to simulate dynamic velocity determination using static data Based on the high-frequency carrier-phase derived Doppler observations, the velocity has been estimated to the precision of 1 cm/s or so, even to the mm/s level. And with the receiver generated Doppler measurements, the precision can reach 3 - 15 cm/s.

Parental involvement and gender differences in the psychological profile of freshmen collegiate athletes

Background： The parent-to-child influences can be adaptive and contribute to the optimal psychological well-being and positive perception of the athlete. Contrary to the healthy parental involvement, a family can also have negative effects on an athlete development. The purpose of this study was to determine gender, father involvement, and mother involvement differences in the psychological profiles of collegiate freshmen athletes as measured by perfectionism, physical self-concept, and psychological well-being. Methods： Eighty-two male and 73 female collegiate freshmen responded to self-reported measures of family involvement, perfectionism, physical self-concept, and psychological well-being. Three separate 2 x 2 x 2 （gender x mother involvement x father involvement） factorial multivariate analysis of variance （MANOVAs） were carried out on the respective subscales from the reported measures. Results： There were significant differences for gender as well as father involvement in perfectionism （p 〈 0.01）. Freshmen females had lower concern over mistakes, and greater levels of organization as well as planfulness than males. Furthermore, freshmen athletes with high involved fathers showed greater levels of high standards for others as well as organization. Conclusion： Father involvement and mother involvement impact perfectionism, physical self-concept, and psychological well-being. perspective. extends through the freshmen year in college as shown in the athletes＇ Future research should develop better measures and utilize a family systems Copyright @ 2012, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved

Compressed Multi-image Reconstruction Based on Quantization Noise Distribution

Because of the quantization noise introduced during the compression,super-resolution reconstruction(SRR)techniques are complicated for the compressed images.This paper aims to incorporate the prior knowledge of discrete cosine transform(DCT)coefficients into modeling the quantization noise.The spatial covariance matrix of the quantization noise is estimated by utilizing the Laplacian distribution of the alternating current(AC)coefficients.After estimating the spatial joint covariance of overall noises for the imaging system,we propose a general Bayesian framework to enhance the resolution for compressed images.Experiments demonstrate the effectiveness of the proposed algorithm and show the superiority to previous methods in objective and subjective aspects.

A Multivariate Public Key Cryptographic Scheme

This paper presents a multivariate public key cryptographic scheme over a finite field with odd prime characteristic.The idea of embedding and layering is manifested in its construction.The security of the scheme is analyzed in detail,and this paper indicates that the scheme can withstand the up to date differential cryptanalysis.We give heuristic arguments to show that this scheme resists all known attacks.

TRUNCATION ERROR REDUCTION METHOD FOR PLANAR CAVITY FLOW

A new so called truncation error reduction method (TERM) is developed in this work. This is an iterative process which uses a coarse grid (2 h ) to estimate the truncation error and then reduces the error on the original grid ( h ). The purpose is to use coarse grids to get more accurate results and to develop a new method which could do coarse grid direct numerical simulation (DNS) for more accurate and acceptable DNS solutions.

A fast acquisition method of DSSS signals using differential decoding and fast Fourier transform

In low earth orbit (LEO) satellite or missile communication scenarios, signals may experience extremely large Doppler shifts and have short visual time. Thus, direct sequence spread spectrum (DSSS) systems should be able to achieve acquisition in a very short time in spite of large Doppler frequencies. However, the traditional methods cannot solve it well. This work describes a new method that uses a differential decoding technique for Doppler mitigation and a batch process of FFT (fast Fourier transform) and IFFT (invert FFT) for the purpose of parallel code phase search by frequency domain correlation. After the code phase is estimated, another FFT process is carried out to search the Doppler frequency. Since both code phase and Doppler frequency domains are searched in parallel, this architecture can provide acquisition fifty times faster than conventional FFT methods. The performance in terms of the probability of detection and false alarm are also analyzed and simulated, showing that a signal-to-noise ratio (SNR) loss of 3 dB is introduced by the differential decoding. The proposed method is an efficient way to shorten the acquisition time with slightly hardware increasing.

Output Speed and Torque of Differential Double-Stator Swing Hydraulic Multimotors

A new type of differential double-stator swing hydraulic motor, based on double stator structure, was introduced. Compared with the traditional swing hydraulic motors, it could provide various kinds of rotational speeds and torques under the same conditions of input flow rate and pressure. The operating prindple and graphic symbols were described. The output speed and torque characters in multifarious connection modes were analyzed through single-acting differential double-stator swing hydraulic multi-motors. Then the differential connection modes and differential principles of differential double-stator swing hydraulic multi-motors were stated. Furthermore, the output speed and torque characters of double- acting and triple-acting ones in multifarious connection modes were gotten. The interaction between output torque and the displacement ratio was studied. Finally, the internal leakage that influenced the volumetric efficiency was researched. The theoretical and experimental researches show that the differential double-stutor swing hydraulic multi-motors can provide various kinds of rotational speeds and torques. Predictably, this new kind of swing hydraulic multi-motors has broad application prospects in machine tool equipments, engineering machineries, and simulation turntables.

Gender Differences in Auditory Perception and Computational Divided Attention Tasks

Women have been stereotyped as better multitaskers when compared to their male counterparts. The purpose of this study is to investigate whether there are differences in gender performance when performing cognitive combined tasks. Twenty-four graduate students （twelve females and twelve males） volunteered to participate in the study. The task requires participants to indicate when they perceive a change in the intensity of an auditory signal while simultaneously solving algebraic problems. Multivariate Analysis of Variance （MANOVA） results reveal no significant differences between genders when performing the combined tasks （p = 0.1831 and 2 = 0.7891） although the average number of false alarms made during the combined tasks by males is nearly 11% higher than the average number of false alarms made by females. However, （Multivariate Analysis of Variance） ANOVA results for the combined tasks show that males outperform females on the computational task while listening for changes in the auditory signal F（1, 22） - 5.09, p 〈 0.03, but there are no significant differences in their ability to detect noise intensity variation or in the number of false alarms made while multitasking. For the single task analysis the ANOVAs indicate no significant differences in signal detection task performance, computational task performance, or the number of false alarms made by males and females.

Iranian English Foreign Language Learners＇ Learning Style Sensory Preferences and Their Speaking Strategy Use Across Proficiency

This study investigates the relationship between Iranian EFL （English as a Foreign Language） learners＇ sensory preferences： Visual, Audial, and Haptic （VAH） and the learners＇ speaking strategy use across proficiency. To this end 146 Iranian EFL learners studying English at different levels of language proficiency, participated in this study. O＇Brien＇s （1990） learning channel preference checklist was given to students to determine their sensory preferences In addition, a Speaking Strategy questionnaire （an adaptation of strategy inventory for language learning （SILL）, focusing on strategies used at the time of Speaking） was also given to the students in another session. The data were analyzed using multivariate ANOVA （MANOVA） in order to probe the relationship between Iranian EFL Learners＇ Learning Style Sensory Preferences and their speaking strategy use across proficiency. Based on the results, it can be claimed that there was a weak to moderate interaction between the proficiency levels and preference of speaking strategies on the learning styles of the Iranian EFL learners.

Generalized Square Conservative Multistep Finite Difference Scheme Incorporating Historical Observations

In this paper,a multistep finite difference scheme has been proposed,whose coefficients are determined taking into consideration compatibility and generalized quadratic conservation,as well as incorporating historical observation data.The schemes have three advantages:high-order accuracy in time,generalized square conservation,and smart use of historical observations.Numerical tests based on the one-dimensional linear advection equations suggest that reasonable consideration of accuracy,square conservation,and inclusion of historical observations is critical for good performance of a finite difference scheme.