面向XML文档的细粒度强制访问控制模型

XML文档存放的信息需要受到访问控制策略的保护.现有的一些面向XML文档的访问控制模型都是基于自主访问控制策略或基于角色的访问控制.高安全等级系统需要强制访问控制来保证系统内信息的安全.首先扩展了XML文档模型使其包含标签信息,并给出了扩展后的文档模型需要满足的规则.然后通过讨论XML文档上的4种操作,描述了面向XML文档的细粒度强制访问控制模型的详细内容.该模型基于XML模式技术,它的控制粒度可以达到文档中的元素或者属性.最后讨论了该模型的体系结构和一些实现机制。

操作系统强制访问控制关键技术研究

强制访问控制能有效地防止用户有意或无意地破坏系统的安全，能够有效地防止病毒和木马以用户的身份破坏系统的安全，是高安全需求操作系统的主要防护手段。业界对操作系统强制访问控制研究起步很早。然而，面对日新月异的应用场景，面对计算机系统及操作系统自身相关技术的迅猛发展，已有的针对操作系统强制访问控制的研究工作不足以兼顾安全性、可用性和灵活性。以上不足集中体现在：1) 当前广泛使用的强制访问控制机制从设计上难以同时满足实用系统对安全性和可用性的要求；2) 强制访问控制的设计缺乏对操作系统所处分布式、网络化环境的考虑；3) 操作系统强制访问控制研发保障技术需要进一步研究。 针对这些问题，本论文从强制访问控制的设计和保障出发，对操作系统强制访问控制关键技术展开研究，并取得了以下几个方面的成果： 第一：强制访问控制格策略模型机制简洁，安全性易验证，在安全操作系统和安全增强操作系统上应用广泛。然而严格地实施格策略会带来可用性的问题。本文针对机密性和完整性强制访问控制格策略模型，分别给出了可监控客体框架和Clark-Wilson可信主体特权状态跃迁监控框架。这些框架具有细的刻画粒度，好的扩展性和简洁性，我们对这些框架给出了数学描述，并对带Clark-Wilson可信主体特权状态跃迁监控框架的完整性格模型给出了理论证明； 第二：针对分布式应用环境，提出了基于可信计算技术和域型实施（Domain and Type Enforcement: DTE）策略的操作系统分布式强制访问控制方案。我们从理论上证明了策略的安全性。相比国内外同类工作，该方案具有细的访问控制粒度，在系统验证的简洁性和部署的灵活性方面是最好的； 第三：实施强制访问控制的中高等级安全操作系统的安全性需要利用形式化方法的严密性进行保证。本文按照TCSEC B2级别的要求，利用Z/EVES形式化工具对SECIMOS安全操作系统进行了形式化保障：给出了安全模型的形式化规范，给出了安全不变量和安全定理，证明了安全定理，描述了形式化安全模型与顶层设计的一致性； 第四：操作系统强制访问控制框架是强制访问控制机制在操作系统上实现的基础。本文提出了针对操作系统强制访问控制框架的自动测试用例生成方案。该方案利用编译器辅助审计代码插入，约束求解器辅助置乱参数生成，测试用例精简等技术为FreeBSD MAC框架生成了一套有效的回归测试用例套件。同时也为基于FreeBSD MAC框架的NFSARK系列安全操作系统提供了坚实的实施基础。 本文的研究成果向圆满解决当前国内操作系统强制访问控制的设计、实施和保障中遇到的问题的目标迈出了坚实的一步。

基于静态分析的强制访问控制框架的正确性验证

现阶段对操作系统的强制访问控制框架的正确性验证的研究主要集中于对授权钩子放置的验证.文中基于TrustedBSD MAC框架对强制访问控制框架的正确性验证问题进行了研究,在授权钩子放置验证的基础上,提出了安全标记的完全初始化验证和完全销毁验证.为了实现上述验证,文中提出了一个路径敏感的、基于用户自定义检查规则的静态分析方法.该方法通过对集成于编译器的静态分析工具mygcc进行扩展来验证强制访问控制框架的钩子放置的准确性和完备性.该方法具有完全的路径覆盖性,且具有低的误报率和时间开销.

基于Biba和Clark-Wilson策略的混合强制完整性模型

商业应用需要实施完整性策略保护.Biba模型提供了一种简洁的多级完整性控制方案,但是需要引入可信主体来保证实施的可用性.而Clark-Wilson模型通过可监控的状态转换提供了一种完备的完整性保护,但其复杂性影响了该模型的完整实现.提出的模型以Biba严格完整性策略为基础,同时根据可信主体在其生命周期所属的状态实施Biba低水标策略.对可信主体在其生命周期发生的状态转换及相应的低水标参数调整,采用Clark-Wilson模型来进行监控.在有效解决了Biba策略的可用性问题和Clark-Wilson模型监控量过大给系统带来的配置和运行负担问题的同时,继承它们的优点.证明了该策略融合方案是可行的、安全的.

Solving MIN UR problem by triangle evolution algorithm with archiving and niche techniques

In this paper, as an extension of minimum unsatisfied linear relations problem (MIN ULR), the minimum unsatisfied relations (MIN UR) problem is investigated. A triangle evolution algorithm with archiving and niche techniques is proposed for MIN UR problem. Different with algorithms in literature, it solves MIN problem directly, rather than transforming it into many sub-problems. The proposed algorithm is also applicable for the special case of MIN UR, in which it involves some mandatory relations. Numerical results show that the algorithm is effective for MIN UR problem and it outperforms Sadegh's algorithm in sense of the resulted minimum inconsistency number, even though the test problems are linear.

港西油田现代油藏管理研究与实践

Through years of practice, reservoir management has already become the basic mode of foreign oil companies to realize the high-efficient development of the oil field. From the view of reservoir development and technological economy, reservoir management regards the study of the reservoir engineering, designs of reservoir projects and the dynamic analysis of the reservoir's performance as a system. In the fields of reservoir description, the establishment of the geological models and development models, the dynamic simulations of reservoir exploitation and the design of the oil engineering, reservoir management emphasizes the cooperation of the geology and the engineering, the combination of the engineering technology and the economic evaluation. In order to provide the means and basis for the reservoir geology study, reservoir evaluation, reserves calculation, numerical simulation, development plan and risk analysis, it adopts the reservoir management activities(team work) to make and implement the optimized oil field development management strategies so that secientific and democratic decision making can be achieved. Under the planned economic system for a long time, the purpose of Chinese reservoir development has been to fulfill the" mandatory" production task. With the deepening of the reform, the management organization of Chinese petroleum enterprises has been gradually going through the transition and reforms to the operational entity and the establishment of the mode of oil companies under the socialist market economy system. This research aims at introducing the advanced reservoir management technique from foreign countries to further improve the reservoir development results and wholly raise the economic benefits of Chinese mature land facieses sandstone reservoirs in the later stage of the water flooding. We are going to set up a set of modern reservoir management modes according to the reservoir features, current situation and existing problems of GangXi oil field of DaGang oil company. Through the study and implementation of the reservoir description and numerical simulation technology effectively, we plan to work out integrated adjustment projects, to study the related technology of oil recovery; to set up the effective confirmable data procedure and data management system of the reservoir management, to establish the coordinated model and workbench related to geology, engineering and economy in order to realize the real time supervision and evaluation on the process of reservoir development. We hope to stipulate modernization management tools for GangXi oil fields to rationally utilize various kinds of existing technological methods and to realize the economic exploitation and achieve the maximum benefits from the reservoir. The project of the modem reservoir management will be carried out on the GangXi oil field of DaGang oil company for this oil field is typical and has integrated foundamental materials and perfect networks. Besides, it is located in the good geographical position enjoying very convenient traffic. Implementing modern reservoir management will raise the recovery ratio, reduce the production cost and improve the working efficiency. Moreover, the popularization of modern reservoir management will improve the comprehensive benefits of DaGang oil company and even the whole Petro China. Through the reserch of this project, the following technical indicators can be reached: Establishing the concept of modern reservoir management. Establishing a set of integrated data information management system adapt to the features of GangXi reservoir. 3. Forming technical research modes of modern reservoir management suitable for mature reservoirs in the later developing stage. 4. Advancing projects of GangXi reservoir which are maxium optimized in engineering technique and economic benefits of oil exploitation. Besides, this set of technology, research principle and method can guide the mature reservoir of DaGang oil field and even the whole PetroChina to develop the further research of reservoir adjustment and improve the reservoir recovery factor and developing level constantly.