普适计算中信任模型的研究*

首先概述了现有两种主要的信任模型以及其存在的问题,然后结合不确定概率理论和普适计算的特点,提出了普适环境下一种新的信任模型——基于属性凭证的信任模型。最后给出了它在实际中的应用。     

自动信任协商中的推理攻击分析

自动信任协商是陌生实体通过交替地披露属性证书建立信任关系的一种方法。主体拥有的不同属性之间可能存在着某种联系，某些属性的披露会导致其它敏感信息的泄露，即推理攻击。本文分析了属性间的线性关系，提出了属性敏感强度的概念，定义了属性敏感强度的偏序关系，在此基础上定义了自动信任协商系统抽象模型。针对几类推理攻击给出了相应的防御方案及其安全性分析。     

一种带有时间域的证书链搜索算法

针对当前基于角色的信任管理语言RT0的不足,提出带有时间域的信任管理语言,在证书的结构中增加了证书的有效期和证书的版本号,并对交集表达式的长度进行了限制。实验表明,带有时间域的信任管理语言使证书链搜索过程变得更加迅速、有效。     

自动信任协商中最优信任证披露序列的构建方法

为了降低自动信任协商中的信任证披露开销,引入资源披露策略树的概念。通过在IKEv2初始交换消息的安全关联载荷中加入完整性级别域和机密性级别域,使之支持自动信任协商策略的安全交换,从而为资源披露策略树的构建提供数据基础。给出最优信任证披露序列搜索算法,它可以从资源披露策略树中搜索效率最优的信任证披露策略。     

一种带有信任度的基于角色的信任管理模型*

在RT（一族基于角色的信任管理语言）的基本部分RT0的基础上提出了新的带有信任度的基于角色的信任管理模型（RTDOT）,将信任度结合到信任管理中,并给出了模糊集合的语义。新模型体现了信任的主观性和模糊性,并可对委托深度进行控制,与模糊理论的结合为信任管理提供了一个新方向。     

CORBA中实现安全代理的截获器研究*

首先介绍了分布式系统中代理的概念和CORBA的SAS协议,提出了实现CORBA安全服务的模型,并详细论述了如何利用截获器技术对CORBA系统中的代理进行设计和实现。     

Context-aware trust negotiation in peer-to-peer service collaborations

Service-oriented architecture (SOA) and Software as a Service (SaaS) are the latest hot topics to software manufacturing and delivering, and attempt to provide a dynamic cross-organisational business integration solution. In a dynamic cross-organisational collaboration environment, services involved in a business process are generally provided by different organisations, and lack supports of common security mechanisms and centralized management middleware. On such occasions, services may have to achieve middleware functionalities and achieve business objectives in a pure peer-to-peer fashion. As the participating services involved in a business process may be selected and combined at run time, a participating service may have to collaborate with multiple participating services which it has no pre-existing knowledge in prior. This introduces some new challenges to traditional trust management mechanisms. Automated Trust Negotiation (ATN) is a practical approach which helps to generate mutual trust relationship for collaborating principals which may have no pre-existing knowledge about each other without in a peer-to-peer way. Because credentials often contain sensitive attributes, ATN defines an iterative and bilateral negotiation process for credentials exchange and specifies security policies that regulate the disclosure of sensitive credentials. Credentials disclosure in the iterative process may follow different orders and combinations, each of which forms a credential chain. It is practically desirable to identify the optimal credential chain that satisfies certain objectives such as minimum release of sensitive information and minimum performance penalty. In this paper we present a heuristic and context-aware algorithm for identifying the optimal chain that uses context-related knowledge to minimize 1) the release of sensitive information including both credentials and policies and 2) the cost of credentials retrieving. Moreover, our solution offers a hierarchical method for protecting sensitive policies and provides a risk-based strategy for handling credential circular dependency. We have implemented the ATN mechanisms based on our algorithm and incorporated them into the CROWN Grid middleware. Experimental results demonstrate their performance-related advantages over other existing solutions.

一个含有信任度的反馈式信任管理模型的设计

提出了一种含有反馈的信任管理模型，将信任度结合到信任管理中，模型具有自主学习反馈的功能，能够将自己及别人的经验融入系统，使系统在学习中不断得到修正完善。通用、灵活、自动学习是本模型的特点。     

网格计算访问控制的实现

随着网格应用的不断建立，解决网格访问控制问题愈发急迫。该文形式化描述了网格访问控制元素，定义了网格用户角色和角色委托概念，分析了网格计算访问控制特性、授权要素、授权模式、授权策略，结合使用代理证书和属性证书提出了一个基于角色的网格计算访问控制实现方案。     

网格安全代理系统--Myproxy

主要介绍一个针对网格入口的安全代理系统——Myproxy，探讨它的实现原理和使用方式，并讨论其存在的安全隐患和相应解决方法。