【作者】 井世忠；

【导师】 董才林；

【作者基本信息】 华中师范大学 ， 运筹学与控制论， 2012， 硕士

【摘要】 随着计算机技术和Internet的迅猛发展,网构软件作为一种新型的软件形态应运而生,它的形成建立在Internet环境中各个异构的软件服务实体间的联盟和有效协同。在没有中心化的管理权威可以依赖的Internet环境中,软件服务实体彼此间的相互信任对软件服务实体及其所在应用系统的安全保障和可靠运行都具有重要的意义,因此,如何对具有主体化和动态演化特点的网构软件进行动态信任评估,是我们必须面对和加以解决的难题。针对现有信任评估模型在信任的不确定性、模糊性方面刻画不足,进而影响信任评估的准确性和动态适应性的问题,作者提出了一种支持信任自动形成和更新的网构软件动态信任评估模型。在网构软件的动态信任评估模型研究中,本课题的主要研究工作包括：(1)对网构软件和现有的信任评估模型进行了研究,并分析了现有信任模型的优缺点,在此基础上提出了一种适用于网构软件的动态信任评估模型,该模型符合人类心理认知习惯。(2)为了反映信任的主观性、模糊性,提出了基于模糊理论的信任模糊综合评判方法,在确定各因素权重时引入信息熵理论,克服了传统方法因主观分配权重而导致信任评估模型动态自适应性不强的缺点。(3)在进行反馈信任聚合计算时,采用直接信任树的方法进行反馈信息的搜索与聚合,同时为了实现系统自动调节聚合计算的规模,引入了推荐层数阈值和可信任阈值。(4)在对直接信任度和反馈信任度进行综合计算时,引入自信系数和反馈系数两个参数自动建立和动态调整直接信任度和反馈信任度的权重。(5)针对行为信任的动态性,结合模糊理论中的贴近度,提出了信任更新机制,可以有效的抵制恶意推荐。最后采用一个多主体建模平台进行模拟实验,结果表明该模型是可行的,且具有更加稳健的动态适应性。更多还原

【Abstract】 With the rapid development of the Internet and computer technology, Internetware emerged as a new software paradigm, which is built upon the coordination of the heterogeneous software services entities in the Internet environment. There is no centralized management authority can rely on the Internet environment, trust is an important thing for security and reliability of software services entities and systems. Therefore, how to conduct dynamic trust evaluation on Internetware, which has the characteristics of subjectivation and dynamic evolution, is a problem which we have to face and resolved.For the existing trust evaluation models cannot reflect the uncertainty, fuzzy of the trust relationships, thereby affecting the trust evaluation accuracy and dynamic adaptability. This paper presents a dynamic trust evaluation model for Internetware, which can support the automatic formation and update of the trust relationships among entities.In the research of Internetware dynamic trust evaluation model, we have done some researches as follows:(1) The existing trust evaluation model and Internetware have been studied, analyzed their advantages and disadvantages, then a dynamic trust evaluation model for Internetware is proposed, which is consistent with human cognitive habits.(2) To reflect subjective and fuzzy nature of trust, a fuzzy comprehensive evaluation method based on fuzzy theory for Internetware is proposed, in which determining the various factors weights we introduce information entropy theory. The method can overcome the shortcomings in determining the weight by the subjective judgments method, and improve dynamic adaptability of trust evaluation model, which is not strong enough as a result of subjective weight distribution by traditional methods.(3) In the feedback trust aggregation computation, the feedback trust information is searched by using Direct Trust Tree. At the same time, two new parameters, feedback level threshold and trust threshold, are introduced to adjust the scale of aggregating computation automatically.(4)In the direct trust and feedback trust comprehensive calculation, two new parameters, confidence coefficient and feedback coefficient, are introduced to establish and adjust the weight of direct trust and feedback trust automatically.(5) According to the dynamic character of behavior trust, a new model of trust renewal is provided, which is based on the degree of approximation in fuzzy theory, and which do better in preventing the malicious feedback. Finally, we use a multi-agent modeling platform for the simulation, and simulation’s results show that, compared to the existing trust quantization metrics, the model in this paper is more robust on trust dynamic adaptability更多还原