带认证邮局协议的密钥恢复攻击

作者提出了一种新的针对带认证邮局协议的密钥恢复攻击,能够更快地恢复出密钥并能够恢复更多的密钥字符.基于通道技术和高级消息修改技术,提出了一种“群满足方案”来确定性地满足分而治之策略下最后一个通道首三步的所有充分条件,籍此提高MD5 (Message Digest Algorithm 5)碰撞对搜索的效率.并提出了一些新的通道来控制MD5碰撞对消息的更多比特的取值,比如可以构造出352比特值确定的MD5碰撞对.通过这些技术改进了多位信息确定的MD5碰撞对搜索效率,应用到APOP的密钥恢复攻击中不仅能够快速恢复长达31个字符的密钥,而且能够在实际时间内恢复长达43个字符的密钥.     

基于Blowfish和MD5的混合加密方案*

针对Blowfish算法在实际应用中存在的等价密钥、重复初始化等问题,提出Blowfish与MD5算法相结合,将MD5算法的生成值作为密钥的一部分对Blowfish算法进行初始化,使用概率统计方法证明该方案弥补了Blowfish算法的实际应用缺陷。计算结果表明,混合加密方案具有更高的安全性、更快的速度。     

一种新型MPLS网络动态重路由算法

提出了一种可以用于恢复工作路径和预先提供的备份路径的重路由算法,它由两个子算法组成:第一个算法用于动态决定恢复范围(RS),通过减少网络拓扑的复杂性和增大已经存在工作LSP的重用来增加恢复速度。第二个是通过动态增加恢复范围直到RS达到整个网络拓扑,来减少失败的概率。通过模拟,根据恢复速度、丢包率、网络资源利用率和现有的LSP的可重用率评价了提出的恢复方案和已经存在的方案的性能。     

一种基于多模式加密算法的文件保护方案*

结合对称密码算法中的DES、IDEA、AES和单向散列算法中的MD5、SHA-1、SHA-256等算法,提出了一种在同一文件内部采用多模式加密的方案,该方案比传统的单一模式加密的方案能更好地保证数据的完整性和安全性.详细描述了该方案的算法实现,通过试验验证了其实用性,同时分析了该方案的优点和不足.     

基于小波变换的分层影象恢复

此文研究了影象恢复问题的小波表示，提出了基于小波变换的分层影象恢复算法。该方法不仅可以改善影象恢复的质量，而且其计算量远远小于通常的影象恢复算法。     

基于拜占庭容错的前摄恢复算法

针对现有拜占庭容错中的恢复算法不适用于主动复制品的这一问题,提出支持有状态复制品的前摄恢复算法。每个复制品维护一个恢复队列。当到达一个检查点后,使用该前摄恢复算法复制品检查恢复队列,在服务复制品发生错误前,提前将复制品恢复成正确的状态。如果复制品已经出错,该算法也适用。实验分析结果显示算法的有效性。     

MD5算法在电话语音系统软件保护中的应用

本文首先对软件保护技术进行了简要的概述，在剖析MD5算法工作原理的基础上，提出了基于MD5加密算法的软件硬加密保护方案。该方案根据机器的CPU序列号和语音卡号使用MD5加密算法自动生成软件序列号，并对MD5加密算法的输入输出数据进行变化处理。结果显示，该方法实现了“一机一码”，并已应用于某“电话语音系统”中。     

软件定义卫星网络的链路故障检测和恢复方案

针对具有星间链路的卫星网络,提出了一种软件定义卫星网络架构下的链路故障检测和恢复方案。首先基于软件定义卫星网络架构设计了一种主动上报式故障检测机制,并设计了链路故障检测算法,实现对卫星网络中链路故障的快速发现和准确定位。在此基础上,提出了一种保护加恢复式故障恢复机制来快速恢复因故障导致的业务中断。最后在原型系统中对该方案进行了验证。实验结果表明,该方案可以在毫秒级的时间内快速检测并准确定位到链路故障,并可以在10±2ms的时间内对故障进行快速恢复。同时,该方案可适用于多种卫星网络拓扑。     

一种适用于通信协议自稳定性的恢复算法

主要提出了一种适用于通信信议自稳定性的恢复算法，先论述了适用于该算法的有关概念及形式描述方法；接着描述了该恢复算法，并给出了该算法的正确性证明及复杂性分析；最后通过一个多进程通信协议的实例研究，验证了该算法的正确性和有效性。     

基于混合概率分布的演化算法在电网负荷恢复中的应用

在电网恢复过程中最后的负荷恢复阶段,寻求全局优化的恢复方案通常都是NP完全问题.在综合考虑负荷恢复阶段中各种不同因素的基础上,建立了基于多目标多约束组合优化的数学仿真模型,并将参数可变的混合概率分布演化算法(EABHPD)引入到模型的求解.该算法通过改变分布函数的参数实现了负荷恢复问题求解精度与计算复杂度的折衷,并且避免了演化算法在搜索遍历过程中陷入局部最优解而过早收敛的问题.仿真实验结果表明算法具有良好性能.     

一种基于MPLS网络的快速故障恢复算法

现有的MPLS故障恢复方案存在不同的性能问题:Makam方案需要提前建立备份路径,浪费了大量网络资源;简单动态方案动态建立备份路径,资源利用率高,但是需要等待路由表收敛,恢复时间长,造成大量丢包.针对这些不足,提出了一种基于MPLS网络的快速故障恢复算法MBFR.MBFR算法在故障发生以后建立备份路径,但是不需要等待路由表收敛,只需根据PIL中信源树和当前故障信息就可以快速计算出备份路径,既不浪费网络资源,又缩小了恢复时间.仿真实验结果验证了MBFR算法的优越性.     

MPLS故障恢复中的丢包与失序研究

该文分析了MPLS网络中的Makam和Haskin两种故障恢复机制,Makam机制会造成的数据包的丢失,Haskin可以避免这个问题,但会导致数据包失序的问题,该文提出了在Haskin的基础上使用缓冲区来避免数据包的失序,并给出了缓冲区大小的估计式,以及估计式中相关参数的近似计算方法.     

Restoration in all-optical GMPLS networks with limited wavelength conversion

A new generation of optical components and the advance of the Generalized Multi-Protocol Label Switching (GMPLS) control plane supporting dynamic provisioning and restoration of optical connections (i.e., lightpaths), brings the vision of the dynamic all-optical network closer to reality. An emerging technology is the conversion between wavelengths, which removes the wavelength continuity constraint, thus allowing an easier and more flexible connection allocation. A limitation in the number of wavelength converters impairs their benefits especially during the restoration phase, when many simultaneous recovery attempts must share residual resources.This paper investigates the restoration performance of GMPLS-controlled all-optical networks with limited wavelength converter deployment. We investigate how different restoration methods, namely span restoration, segment restoration, and end-to-end restoration are affected by the availability of a limited number of wavelength converters at each node. For this purpose an enhanced wavelength assignment scheme compliant with GMPLS signaling is exploited, aiming at saving converters by assigning a higher preference to wavelengths not requiring conversion. An extensive simulation study has been conducted comparing the performance of this scheme to the most advanced scheme based on standard GMPLS signaling for the three restoration methods.Simulation results show that the enhanced wavelength assignment scheme significantly reduces the number of wavelength converters (WCs) necessary to achieve good recovery performance. The enhanced scheme especially improves span restoration performance, where the matching between the stubs’ and recovery segment wavelength may require a WC. End-to-end restoration is the least affected, due to a higher degree of freedom in the route choice, while segment restoration performance lies in between.     

基于MPLS两种快速重路由模型仿真研究

对MPLS两种快速重路由模型即Haskin和Makam模型进行简单介绍的基础上，详细介绍如何用Ns-2对两种模型中的Haskin模型建立场景，并对两种模型的场景进行仿真比较，实验结果证明该两种模型在时间延迟和丢包上各有优缺点，在实际应用中应综合考虑这两种模型。     

基于RSVP-TE的网状IPO全光网络的快速故障恢复算法

网状全光IPO(IP over Optical)网的故障恢复是一个研究的热点，主要研究点都是基于保护通路的计算算法和波长分配算法等，但是缺乏一种快速的恢复建立的机制．本文提出了一种采用基于扩展了的RSVP-TE协议的快速的故障恢复机制，在大大节约网络带宽的同时又能获得很好的保护性能．文中还给出了算法的延时的评估公式和仿真计算的结果．     

Pixel rearrangement based statistical restoration scheme reducing embedding noise

In this paper, a block based steganographic algorithm has been proposed where a sequence of secret bits are embedded into a set of pixels by rearranging the pixel locations. This algorithm has been devised as an improvement over existing statistical restoration based algorithms in order to reduce the additive noise which occurs due to embedding. It is shown that the proposed scheme substantially reduces the additive noise compared to existing statistical restoration based schemes.     

一种MPLS网络分割策略及故障恢复机制

基于网络通信业务的不断增加,网络规模的增大和复杂程度的提高给现有的集中式故障管理和恢复带来了困难。本文着重提出了一种全新的MPLS网络分割策略。这种策略将大型网络分割成基于边缘路由器的一级域和不包含边缘路由器的二级域。尽量在每个域内实现故障分布式管理和恢复,并给出了基于域的故障恢复机制。     

基于相交多路径的组播主动式恢复方案

提出了基于相交多路径的组播主动式恢复方案。该方案通过为树中节点提供备用父节点的方式,计算组播源到各个组成员的多条相交路径来代替不相交双树。相交多路径保证了构建成功率并为组播路由提供一定程度的保护。仿真结果表明,该方案构建的组播树以及故障恢复后组播树的代价均与现有方案相当,但是提供的故障恢复时间与现有方案相比显著缩短。     

Numerical Schemes of Shock Filter Models for Image Enhancement and Restoration

Considerable interest has recently been given to signal processing models based on partial differential equations. Successively improved models based on hyperbolic partial differential equation types are proposed in the literature. These models yield interesting results; however, it would be of great interest to generalize them in order to increase their efficiency. In this paper, we propose a generalized shock filter model for one-dimensional signal restoration. After justifying the existence and uniqueness of the solutions in an adequate vector space, we propose an effective numerical scheme to discretize the proposed model, and derive a two-dimensional numerical scheme directly from the one-dimensional model following a space-split strategy. We then prove a stability result for both schemes. We conclude our study by providing high-quality experimental results for one- and two-dimensional signal enhancement and restoration, and showing the influence the shock speed control has on processing time.     

Particle Swarm Optimization Based Support Vector Regression for Blind Image Restoration

This paper presents a swarm intelligence based parameter optimization of the support vector machine (SVM) for blind image restoration. In this work, SVM is used to solve a regression problem. Support vector regression (SVR) has been utilized to obtain a true mapping of images from the observed noisy blurred images. The parameters of SVR are optimized through particle swarm optimization (PSO) technique. The restoration error function has been utilized as the fitness function for PSO. The suggested scheme tries to adapt the SVM parameters depending on the type of blur and noise strength and the experimental results validate its effectiveness. The results show that the parameter optimization of the SVR model gives better performance than conventional SVR model as well as other competent schemes for blind image restoration.