基于格构造非交互不可展承诺方案

NTRU是基于格归约困难问题的公钥密码体制,目前主要用于公钥加密及数字签名。利用N"I'RU实现了 一个非交互不可展承诺方案,其安全性基于格上CVP困难问题,实现了承诺者绑定性。它基于抗碰撞Hash函数的 安全性对承诺合法性进行验证,通过随机映射扰动明文,使明文具有随机分布特性,以实现验证者隐藏性以及与揭示 有关的不可展性质。本方案具有N I'RU快速高效的特点,同时可抵杭信道窃听攻击、消息重放攻击及复制承诺攻击。     

一种构造并发不可延展零知识的新方法

构造了一个新的并发不可延展的零知识论证系统,具有更好的鲁棒性.新方案基于Feige-Shamir结构而设计,以具有鲁棒性的不可延展承诺方案以及巧妙设计的证据不可区分性证明为基本组件,来实现并发不可延展性和鲁棒性.此外,对敌手视图的模拟借助了"茫然模拟"的策略.当与其它协议并发组合时,该方案更易于分析和应用.基于单向函数假设,该方案的轮复杂性为超对数.     

One-round identity-based key exchange with Perfect Forward Security

Identity-based authenticated key exchange (IBAKE) protocol is one of the most important cryptographic primitives that enables two parties using their identities to establish their common secret keys without sending and verifying public key certificates. Recently, many works have been dedicated to design efficient and secure IBAKE protocols without bilinear pairings which need the heavy computational cost. Unfortunately, most of the proposed protocols cannot provide Perfect Forward Security (PFS) which is a major security goal of authenticated key exchange protocols. In this paper we present an efficient and provably secure IBAKE protocol with PFS. Our protocol relies on the technique known as the concatenated Schnorr signature and it could be viewed as a variant of the protocol proposed by Fiore et al. in 2010. By using the Canetti–Krawczyk security model, we prove that the protocol is secure with PFS under the Computational Diffie–Hellman assumption in the random oracle model. The protocol is of interest since it offers a remarkable combination of advanced security properties and efficiency and its security proof is succinct and intelligible.     

Non-interactive automatic video segmentation of moving targets

Extracting moving targets from video accurately is of great significance in the field of intelligent transport.To some extent,it is related to video segmentation or matting.In this paper,we propose a non-interactive automatic segmentation method for extracting moving targets.First,the motion knowledge in video is detected with orthogonal Gaussian-Hermite moments and the Otsu algorithm,and the knowledge is treated as foreground seeds.Second,the background seeds are generated with distance transformation based on foreground seeds.Third,the foreground and background seeds are treated as extra constraints,and then a mask is generated using graph cuts methods or closed-form solutions.Comparison showed that the closed-form solution based on soft segmentation has a better performance and that the extra constraint has a larger impact on the result than other parameters.Experiments demonstrated that the proposed method can effectively extract moving targets from video in real time.     

Commitments and interaction norms in organisations

In an organisational setting such as an online marketplace, an entity called the ‘organisation’ or ‘institution’ defines interaction protocols, monitors agent interaction, and intervenes to enforce the interaction protocols. The organisation might be a software system that thus regulates the marketplace, for example. In this article we abstract over application-specific protocols and consider commitment lifecycles as generic interaction protocols. We model interaction protocols by explicitly-represented norms, such that we can operationalise the enforcement of protocols by means of norm enforcement, and we can analyse the protocols by a logical analysis of the norms. We adopt insights and methods from commitment-based approaches to agent interaction as well as from norm-based approaches to agent behaviour governance. First, we show how to use explicitly-represented norms to model commitment dynamics (lifecycles). Second, we introduce an operational semantics to operationalise norm enforcement. Third, we show how to logically analyse interaction protocols by means of commitment dynamics and norm enforcement. The model, semantics, and analysis are illustrated by a running example from a vehicle insurance domain.     

Conventions and Commitments in Distributed CSCW Groups

Conventions are necessary to establish in any recurrentcooperative arrangement. In electronic work, they are importantso as to regulate the use of shared objects. Based on empiricalresults from a long-term study of a group cooperating inelectronic work, I present examples showing that the group failedto develop normative convention behavior. These difficulties informing conventions can be attributed to a long list of factors:the lack of clear precedents, different perspectives among groupmembers, a flexible cooperation media, limited communication, thedesign process, and discontinuous cooperation. Further, I arguethat commitments to the conventions were difficult, due to theconventions not reaching an acceptance threshold, uneven payoffs,and weak social influences. The empirical results call for aspecific set of awareness information requirements to promoteactive learning about the group activity in order to support thearticulation of conventions. The requirements focus on the roleof feedback as a powerful mechanism for shaping and learningabout group behavior.     

Specifying and Monitoring Interactions and Commitments in Open Business Processes

Business processes are increasingly complex and open because they rely on services that are distributed geographically and across organizations. So, they're prone to several points of failure. Monitoring, therefore, remains an important concern. A new approach specifies and monitors interactions among heterogeneous services by tracking their commitments. This approach extends recent research that views business process design as a composition of interaction protocols. It specifies and monitors policies and commitments as a way to monitor service-level agreements and recover from process failures.     

Perfect Matching and Polymatroids

It is shown that any graph has a perfect matching if and only if a specially defined vector is the base of extended polymatroid associated with submodular function defined on subsets of vertex set. Based on this fact, different algorithms for testing flow feasibility can be used to find some perfect matching in a given graph.     

基于效用的Agent多动作选择承诺机制

研究以KARO为逻辑框架的多动作选择承诺,给出与其相关的效用函数计算方法。在引入模型状态迁移概念和相关函数、谓词后,对各种承诺建立和取消承诺的情况进行了形式化,详细给出了kripke型可能世界语义描述。丰富了KARO逻辑框架关于承诺的研究。使主体在合作时,可以充分考虑自己的情况,理性的作出选择,提高多主体间合作的协调性。     

Perfect matchings and extended polymatroid

The classical conditions of the existence of a perfect matching in bipartite graphs are used directly or indirectly to solve the assignment problem by the well-known algorithms. In the paper, we define a vector and an extended polymatroid for a bipartite graph so that the bipartite graph has a perfect matching if and only if the vector is the basis of the extended polymatroid. The study was partially sponsored by INTAS, grant 06-1000017-8909. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 173–179, May–June 2008.     

完善保密的再认识

仙农提出了完善保密的概念并且证明了某些密码体制是完善保密的。就仙农对某些密码体制是完善保密的证明过程进行了分析,指出了其中对Bayes定理的误用,错误在于把不同的前提条件下的概率混淆带入了Bayes定理的等式中,举例证明这些密码体制不是完善保密的,为进一步完善密码体制的安全性提供了基础。引出了概率论的新方向,对多个条件下的概率折衷计算问题进行了相应的讨论。     

刘世平:冰火性情的完美结合

刘世平像一把"冰火"中磨砺出鞘的宝剑。他有冰的理性与智慧,又似火一般的热情奔放,在他身上可以感受到冰火交融的稳健和热诚。十年磨一剑,而他已在技术研发与客户服务中遨游多年,这冰火气质的深巷背后,我们探询到的是坦坦荡荡的心胸,无论是对自己、对朋友、对事业。     

下一代网络与多媒体通信的完美结合

文章介绍了下一代网络的特点与结构，给出了下一代网络的多媒体解决方案及其分层结构，介绍了各个网元的功能，指出下一代网络中尚待解决的若干问题及下一步工作。     

NIST and NSA: Perfect together

The new director of the National Institute of Standards and Technology, Dr Raymond Kammer, has told the US Senate Subcommittee for Technology and Space that his agency and the National Security Agency (NSA) have worked very closely together in many computer security efforts.     

绘画艺术与心理的完美结合

艺术是一种用形象来反映现实但比现实有典型性的社会意识形态,而其中的绘画艺术作为一种非语言的沟通工具,可以让观察者了解语言文字无法揭示的东西,同时绘画艺术的存在是与心理完美结合着的,共同服务于人类社会。     

网络空间安全与意识形态安全

互联网的迅猛发展,使得中国面临着一些较为复杂的意识形态问题和社会舆论问题。一些西方国家通过互联网,对我国实施资本主义性质的文化入侵,企图从意识形态上实现对中国的控制。由此可见,网络空间安全与意识形态安全既关系着我国的生存发展命脉,也直接反映出中国的国家软实力,必须引起高度重视。     

Perfect correspondences between dot-depth and polynomial-time hierarchies

We introduce the polynomial-time tree reducibility (ptt-reducibility) for formal languages. Our main result establishes a one–one correspondence between this reducibility and inclusions between complexity classes. More precisely, for languages B and C it holds that B ptt-reduces to C if and only if the unbalanced leaf-language class of B is robustly contained in the unbalanced leaf-language class of C. Formerly, such correspondence was only known for balanced leaf-language classes. Moreover, we show that restricted to regular languages, the levels 0, 1/2, 1, and 3/2 of the dot-depth hierarchy are closed under ptt-reducibility. Our results also have applications in complexity theory: We obtain the first gap theorem of leaf-language definability above the Boolean closure of NP.     

Modelling the Garden of Perfect Brightness

The Yuan Ming Yuan, the Garden of Perfect Brightness, was the culmination of the art of Chinese Imperial gardens. Covering 350 hectares (875 acres) northwest of Beijing, it included 140 distinct sites, 2000 structures, thousands of pieces of furniture and precious objects, countless plants. It was almost totally destroyed in 1860 at the end of the second Opium War by English and French troops in one of the worst acts of cultural vandalism in recorded history. Rebuilding it has proven impossible, but now computer technology, based on 130 years of scholarly documentation makes it possible to build an accurate and detailed model, and will allow us to experience at least virtually the beauty and grandeur that was the Yuan Ming Yuan. This paper describes a project to build such a model, and details the main challenges and difficulties encountered. While commercially available graphics workstations and modelling software can take us most of the way in this task, they fall short with the modelling of natural phenomena such as plants, rocks and bodies of water. In addition the sheer size of the resulting database pushes rendering engines past their limits.     

DEH阀门管理逻辑的完善

焦作电厂从1999年10月开始先后对6台220MW火电机组进行了DEH改造，针对改造后出现的再热器超压这一异常现象，从阀门管理的角度分析了原因，提出了较好的解决办法。