几类密码算法的神经网络差分区分器的改进

为了进一步研究神经网络在密码分析方面的应用,利用深度残差网络和传统差分密码分析技术构造并改进了几类典型的轻量级分组密码算法的神经网络差分区分器。主要取得以下结果:①分别构造了4~7轮PRESENT、3轮KLEIN、7~9轮LBlock和7~10轮Simeck 32/64的神经网络差分区分器,并基于密码的分组结构分别进行了分析;②基于SPN结构分组密码的特点对PRESENT和KLEIN的神经网络差分区分器进行了改进,最多可提高约5.12%的准确率,并在对LBlock的神经网络差分区分器进行研究时验证得出这种改进方式不适用于Feistel结构的分组密码;③基于Simeck 32/64本身密码算法的特点对其神经网络差分区分器进行改进,提高了约2.3%的准确率。同时,将Simeck 32/64的改进方法与多面体差分分析进行结合,将已有的8轮和9轮Simeck 32/64多面体神经网络差分区分器的准确率提高了约1%和3.2%。最后,将实验中得到的3类神经网络差分区分器模型分别应用到11轮Simeck 32/64的最后一轮子密钥恢复攻击中,其中最佳的实验结果是在1000次攻击实验中以26.6的数据复杂度达到约99.4%的攻击成功率。

区分服务网络中的动态资源管理

为提高区分服务网络资源的管理效率,提出一种动态的资源管理算法,通过测量网络实际流量判断是否接纳资源预留请求,采用带宽代理实现网络数据的接纳控制,并用NS2工具对网络模型进行仿真。仿真实验结果表明,该算法能够使区分服务网络的数据处理能力得到有效提升。

区分服务网络中自适应加权调度方案的研究

针对现有区分服务网络中多服务间带宽公平性问题,提出了一种自适应加权调度方案。该方案通过对本地节点缓存区指标的定期测量,计算得到在各队列间公平分配剩余带宽的调度权值。仿真结果表明,该方案可以在网络负载变化时自适应的快速调整到理想调度值,有效改进了带宽分配的公平性。

区分服务网络TCP流带宽的公平性

区分服务是IP网络中提供服务质量保证的一种方案。区分服务网络中,处于同一个带宽保证业务类中的多个TCP流由于各个流的特性差异,在实际获得带宽时存在公平性问题需要解决。基于网络仿真器NS2,我们研究了分组长度对TCP流带宽公平性的影响,提出了一种基于RED算法支持TCP流实现带宽公平分配的方法,并通过仿真实验分析了性能。

区分服务网络的协作可调整RED算法

文章描述了一种适用于区分服务网络的新的RED改进算法——协作可调整RED算法(CARED)。算法的思想是基于令牌桶标记器的标记概率建立业务实际速率与承诺速率间的定量关系,并以这个关系动态调整下游节点中CARED的丢包概率。为了实现CARED,文章还提出了一种标记概率的计算方法——基于包数的滑动窗口测量算法(NSWM)。文中通过详实的仿真实验证明了定量关系的正确性,同时验证了CARED算法不仅为区分服务提供了有效的拥塞控制功能,也保障了区分服务的不同性能要求。

基于反演滑模控制的区分服务网络拥塞控制算法

针对区分服务网络的两种典型业务类型(奖赏业务和确保业务)分别进行分析和控制,应用非线性流体流理论建立区分服务网络模型,设计推导出一种新的自适应滑模控制器.先将非线性流体流模型转化为参数严格反馈的形式,然后应用反演控制理论完成控制器的设计.通过该方法设计的自适应反演滑模控制器,能够抑制系统的未知动态和不确定性扰动,使缓冲器队列长度的调节达到理想效果.在理想滑动模态下系统渐近稳定,仿真结果进一步验证了该控制器的有效性.

一种区分服务网络的设计与实现

给出了DiffServ网络的一种设计与实现,提出了一种有效的资源管理模型。在该模型中,存在一个带宽代理(BandwidthBroker)同步多个边界节点的接纳控制,负责区分服务网络之间的SLA(ServerLevelAgreement)协商,进行路由器配置;边界节点使用RSVP[3]协议为集聚流预留资源;RSVP使用预计算QoS路由寻找路径。整个模型不仅综合了已有资源管理方案的优点,而且保持了区分服务网络的可扩展性。

基于区分深度置信网络的病害图像识别模型

对枸杞病害进行及时、准确地检测识别对于病害的监测、预测、预警、防治和农业信息化、智能化建设具有重要意义。研究提出了一种基于区分深度置信网络的枸杞病害图像分类识别模型。首先,把枸杞叶部病害图像通过自动裁剪方式获得包含典型病斑的子图像,再采用复杂背景下的图像分割方法分割病斑区域,提取病斑图像的颜色特征、纹理特征和形状特征共计147个,结合区分深度置信网络和指数损失函数建立了病害识别模型。实验结果表明,该方法对于病害图像识别效果较好,与支持向量机相比,基于区分深度置信网络的病害图像识别模型高效地利用了底层图像特征的高层表示,解决了没有足够标注数据时的图像识别问题。

基于神经网络区分器的SIMON-like算法参数安全性评估

神经网络区分器作为一种新的可被应用于密码算法安全性分析的工具,一经提出便被应用于多种密码算法的安全性分析。对于SIMON-like算法,其循环移位参数的选择有多种。利用神经网络区分器对分组长度为32 bit的SIMON-like算法的循环移位参数(a,b,c)的安全性进行了研究,并给出了好的循环移位参数选择。利用Kölbl等在CRYPTO2015中提出的SIMON-like算法仿射等价类思想,将分组长度为32 bit的SIMON-like算法的循环移位参数划分至509个等价类,并选择其中使gcd(a-b,2)=1成立的240个等价类进行研究。针对240个等价类的代表元构建了自动化搜索差分路径的SAT/SMT模型,并利用SAT/SMT求解器搜索了不同代表元的多轮最佳差分路径。利用搜索得到的最佳差分路径的输入差分训练了神经网络区分器,选择其中准确率最高的神经网络区分器作为代表元的神经网络区分器,统计了不同代表元的神经网络区分器准确率。发现Kölbl等给出的20个最佳循环参数并不能使神经网络区分器的准确率最低,而且其中4个循环移位参数对应的神经网络区分器的准确率超过了80%,这意味着这4个循环移位参数抗神经网络区分器的能力是差的。综合考虑Kölbl等的选择和不同代表元的神经网络区分器准确率,给出了3个好的循环移位参数选择,即(6,11,1)、(1,8,3)和(6,7,5)。

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。

区分服务下增强型动态RIO算法改进

鉴于区分网络中的标记算法和队列管理对服务公平性有很大影响,进行了基于增强型动态RIO(Enhanced Dynamic RED with In/Out bit,EDRIO)的确保服务下公平性的改进研究.首先从同构聚集流下的不同大小分组来分析各个分组间的公平性,然后从不同聚集流分配不同带宽来研究异构下的公平性.最后从数据包大小、目标速率及聚集流中包含的单流数量等进行性能仿真.实验结果表明,无论在同构还是异构下,基于EDRIO聚集流之间的公平性都比RIO和动态RIO聚集流之间的公平性好,而且该算法具有很好的扩展性.

区分服务下组播问题研究

区分服务体系结构同样也适合需要服务质量支持的组播应用,然而,IETF至今尚未公布区分服务下的组播服务细节.本文列出了IP组播直接用于区分服务网络引起的几个导致其他的组成员服务质量受损的问题,分析了当前几种可行解决方案及其优缺点,并简要介绍了一种新的解决方案QoSAMDD,并对其进行了仿真实验.

NS-3仿真环境中IEEE802.11服务区分机制的研究

无线局域网采用IEEE 802.11协议无法向不同类型的数据流提供有区分的服务质量,而IEEE 802.11e服务区分机制EDCA存在数据流传输不公平性的问题。为此,运用NS-3网络仿真器实现一种改进的服务区分机制F-DCF。针对每个单独的节点给出排队规则,以保证节点内的公平传输机会,并通过使用基于竞争的接入方法设计实现多个节点之间的公平信道接入机制。仿真结果表明,与传统EDCA机制相比,F-DCF机制可对网络中不同优先级的数据流提供比例公平性的服务质量区分,并能够提高网络的总吞吐量。

N-S EQUATION CALCULATIONS ON MULTI-ELEMENT AIRFOILS WITH ZONAL PATCHED GRIDS

For a complex flow about multi-element airfoils a mixed grid method is set up. C-type grids are produced on each element′s body and in their wakes at first, O-type grids are given in the outmost area, and H-type grids are used in middle additional areas. An algebra method is used to produce the initial grids in each area. And the girds are optimized by elliptical differential equation method. Then C-O-H zonal patched grids around multi-element airfoils are produced automatically and efficiently. A time accurate finite-volume integration method is used to solve the compressible laminar and turbulent Navier-Stokes (N-S) equations on the grids. Computational results prove the method to be effective.

深度学习在ARX分组密码差分分析的应用

随着计算机设备的飞速更新,先进的硬件和高效的计算能力让密码分析学者们越来越关注深度学习,基于深度学习的密码分析近年来成为研究热点.本文应用深度残差网络对分组密码进行差分分析,主要得到以下三项结果.第一,探究了神经网络模型面对密码算法的不同线性运算部件时的表现.基于控制变量法的思想,构造了Speckey和LAX32两类分组密码的神经网络差分区分器.结果表明,Speckey的有效区分器最高为7轮,准确率为0.69;LAX32的有效区分器最高为4轮,准确率为0.55.第二,以SIMON32/64为例,使用四类不同的输入数据格式分别训练了其7–10轮的神经网络差分区分器.分析结果发现,输入数据所含信息量不同时,相同轮数的区分器准确率的差距最多可达0.18.神经网络对所输入的密码信息的利用能力是存在局限性的,输入信息量达到一定程度后不会再使神经网络差分区分器的准确率提高.最后,将训练好的神经网络差分区分器应用到密钥恢复攻击中,对11轮SIMON32/64进行了部分密钥恢复攻击,当选择2~8个明文对时,在1000次攻击中成功率可达95.6%.

Relationships Between Fractal Road and Drainage Networks in Wuling Mountainous Area:Another Symmetric Understanding of Human-Environment Relations

Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry between physical and human systems through fractal analysis of the road and drainage networks in Wuling mountainous area. We found that both the road and drainage networks reflect weak clustering distributions. The evolution of the road network shared a significant self-organizing composition, while the drainage network showed obvious double fraetal characteristics. The geometric fractal dimension of the road network was larger than that of the drainage network. In addition, when assigned a weight relating to hierarchy or length, neither the road network nor drainage network showed a fractal property. These findings indicated that the fractal evolution of the road network shared certain similarities with fractal distribution of the drainage network. The symmetry between the two systems resulted from an interactive process of destroying symmetry at the lower order and reconstructing symmetry at the higher order. The relationships between the fractal dimensions of the rural-urban road network, the drainage network andthe urban system indicated that the development of this area was to achieve the symmetrical isomorphism of physical-human geographical systems.

A Utility-Based Buffer Management Policy for Improving Data Dissemination in Opportunistic Networks

In opportunistic networks, most existing buffer management policies including scheduling and passive dropping policies are mainly for routing protocols. In this paper, we proposed a Utility-based Buffer Management strategy(UBM) for data dissemination in opportunistic networks. In UBM, we first design a method of computing the utility values of caching messages according to the interest of nodes and the delivery probability of messages, and then propose an overall buffer management policy based on the utility. UBM driven by receivers completely implements not only caching policies, passive and proactive dropping policies, but also scheduling policies of senders. Simulation results show that, compared with some classical dropping strategies, UBM can obtain higher delivery ratio and lower delay latency by using smaller network cost.

Allocation optimization of bicycle-sharing stations at scenic spots

Bicycle-sharing system is considered as a green option to provide a better connection between scenic spots and nearby metro/bus stations. Allocating and optimizing the layout of bicycle-sharing system inside the scenic spot and around its influencing area are focused on. It is found that the terrain, land use, nearby transport network and scenery point distribution have significant impact on the allocation of bicycle-sharing system. While the candidate bicycle-sharing stations installed at the inner scenic points, entrances/exits and metro stations are fixed, the ones installed at bus-stations and other passenger concentration buildings are adjustable. Aiming at minimizing the total cycling distance and overlapping rate, an optimization model is proposed and solved based on the idea of cluster concept and greedy heuristic. A revealed preference/stated preference （RP/SP） combined survey was conducted at Xuanwu Lake in Nanjing, China, to get an insight into the touring trip characteristics and bicycle-sharing tendency. The results reveal that 39.81% visitors accept a cycling distance of 1-3 km and 62.50% respondents think that the bicycle-sharing system should charge an appropriate fee. The sttrvey indicates that there is high possibility to carry out a bicycle-sharing system at Xuanwu Lake. Optimizing the allocation problem cluster by cluster rather than using an exhaustive search method significantly reduces the computing amount from O（2^43） to O（43 2）. The 500 m-radius-coverage rate for the alternative optimized by 500 m-radius-cluster and 800 m-radius-cluster is 89.2% and 68.5%, respectively. The final layout scheme will provide decision makers engineering guidelines and theoretical support.

AN IMPROVED GN ALGORITHM OF NETWORK COMMUNITY DETECTION METHOD

.GN algorithm has high classification accuracy on community detection, but its time complexity is too high. In large scale network, the algorithm is lack of practical values. This paper puts forward an improved GN algorithm. The algorithm firstly get the network center nodes set, then use the shortest paths between center nodes and other nodes to calculate the edge betweenness, and then use incremental module degree as the algorithm terminates standard. Experiments show that, the new algorithm not only ensures accuracy of network community division, but also greatly reduced the time complexity, and improves the efficiency of community division.

Using analytic network process to analyze problems for implementing turn-key construction projects in Taiwan

The turn-key construction project is implemented in Taiwan not by a single company but by a make-shift group of several companies. Hence,problems to coordinate the professional construction management (PCM) and the supervising architectural company often occur for the lack of long-term experience to work together. The various factors that affect the implementation of turn-key projects currently practiced in Taiwan are analyzed using the analytic network process (ANP). The objective is to study how the twelve key factors in the four layers of "Role assignment","Signing contract","Operational procedures" and "Losing capital investment" affect the progress of implementing the turn-key project in Taiwan. The results reveal that "Delay in payment" has the most negative influence with 15.62% weighing factor; "Latent risk" comes next with 11.14% weighing factor,and "Responsibility of construction company for project quality" is the third with 10.79% weighing factor.