网格访问控制与授权模型的设计与实现

访问控制和资源授权是网格系统中资源与用户的关系策略的集合,分析了访问控制与资源授权的设计原则,提出了一种基于禁止表和允许表的网格用户访问控制层次式AB4L访问控制模型.给出了该模型的形式化定义,叙述了基于Postgres数据库的资源访问控制模型和授权的实现方法,并从完备性、可扩展性、自主控制和安全性方面对该模型进行了性...     

Role-based access control models

Security administration of large systems is complex, but it can be simplified by a role-based access control approach. This article explains why RBAC is receiving renewed attention as a method of security administration and review, describes a framework of four reference models developed to better understand RBAC and categorizes different implementations, and discusses the use of RBAC to manage itself     

Role-based access control for a Grid system using OGSA-DAI and Shibboleth

In this paper, we propose a new role-based access control (RBAC) system for Grid data resources in the Open Grid Services Architecture Data Access and Integration (OGSA-DAI). OGSA-DAI is a widely used framework for integrating data resources in Grids. However, OGSA-DAI’s identity-based access control causes substantial administration overhead for the resource providers in virtual organizations (VOs) because of the direct mapping between individual Grid users and the privileges on the resources. To solve this problem, we used the Shibboleth, an attribute authorization service, to support RBAC within the OGSA-DAI. In addition, access control policies need to be specified and managed across multiple VOs. For the specification of access control policies, we used the Core and Hierarchical RBAC profile of the eXtensible Access Control Markup Language (XACML); and for distributed administration of those policies and the user-role assignments, we used the Object, Metadata and Artifacts Registry (OMAR). OMAR is based on the e-business eXtensible Markup Language (ebXML) registry specifications developed to achieve interoperable registries and repositories. Our RBAC system provides scalable and fine-grain access control and allows privacy protection. It also supports dynamic delegation of rights and user-role assignments, and reduces the administration overheads for the resource providers because they need to maintain only the mapping information from VO roles to local database roles. Moreover, unnecessary mapping and connections can be avoided by denying invalid requests at the VO level. Performance analysis shows that our RBAC system adds only a small overhead to the existing security infrastructure of OGSA-DAI.     

基于角色的访问控制模型及其面向对象的建模

访问控制是信息安全的一个研究方向,基于角色的访问控制(RBAC)是目前理论研究和应用研究比较广泛的一种模型。详细介绍了RBAC96模型家族的特征和它所遵循的安全准则,并引入面向对象的思想,采用统一建模语言(UML)对RBAC96进行了静态和动态建模,这样就缩短了理论模型和实际系统开发之间的差距,有助于信息系统安全的面向对象的分析与设计。     

电子现金系统的RBAC管理方案

在基于电子现金的网络支付方案中,交易过程相关的多个实体有不同类型的权限和访问标准,如果各自进行安全管理,会使得整个系统的维护协调有很大难度。因此,横跨多个实体的权限管理带来了额外的安全性挑战。分析了基于RBAC的电子现金系统的权限管理策略,通过基于常规角色的授权实现了对电子现金系统内多个实体的访问控制,并设置与常规角色互斥的管理角色实现系统的分布式自行管理．     

网格服务中基于XACML和SAML的安全访问控制

为了解决网格环境下资源访问控制存在的安全性问题,通过分析可扩展访问标记语言XACML、安全声明标记语言SAML及其相关技术,提出了一个基于XACML和SAML的访问控制模型。模型采用可扩展访问标记语言XACML描述访问控制的授权策略,以SAML声明为载体传递用户认证和授权信息,提供安全、细粒度的访问控制,具有较高的灵活性和可扩展性。     

复合模式的网格系统信任授权模型

作为研究焦点的网格系统提供了一种受控的跨边界的资源共享的虚拟框架。对网格环境进行了分析,讨论了网格对信任管理的需求。在分析各种信任模型不足的基础上,基于网格具体的应用环境,并结合以PGP用户为中心的信任模型和SPKI授权证书机制各自的优势,提出了复合模式的网格信任授权模型,并完整设计了整个模型的可实现框架。     

Role-based access control with X.509 attribute certificates

We adapted the standard X.509 privilege management infrastructure to build an efficient role-based trust management system in which role assignments can be widely distributed among organizations, and an XML-based local policy determines which roles to trust and which privileges to grant. A simple Java API lets target applications easily incorporate the system. The Permis API has already proven its general utility in four very different applications throughout Europe.     

Enhancing grid security by fine-grained behavioral control and negotiation-based authorization

Nowadays, Grid has become a leading technology in distributed computing. Grid poses a seamless sharing of heterogeneous computational resources belonging to different domains and conducts efficient collaborations between Grid users. The core Grid functionality defines computational services which allocate computational resources and execute applications submitted by Grid users. The vast models of collaborations and openness of Grid system require a secure, scalable, flexible and expressive authorization model to protect these computational services and Grid resources. Most of the existing authorization models for Grid have granularity to manage access to service invocations while behavioral monitoring of applications executed by these services remains a responsibility of a resource provider. The resource provider executes an application under a local account, and acknowledges all permissions granted to this account to the application. Such approach poses serious security threats to breach system functionality since applications submitted by users could be malicious. We propose a flexible and expressive policy-driven credential-based authorization system to protect Grid computational services against a malicious behavior of applications submitted for the execution. We split an authorization process into two levels: a coarse-grained level that manages access to a computational service; and a fine-grained level that monitors the behavior of applications executed by the computational service. Our framework guarantees that users authorized on a coarse-grained level behave as expected on the fine-grained level. Credentials obtained on the coarse-grained level reflect on fine-grained access decisions. The framework defines trust negotiations on coarse-grained level to overcome scalability problem, and preserves privacy of credentials and security policies of, both, Grid users and providers. Our authorization system was implemented to control access to the Globus Computational GRAM service. A comprehensive performance evaluation shows the practical scope of the proposed system.

A temporal access control mechanism for database systems

The paper presents a discretionary access control model in which authorizations contain temporal intervals of validity. An authorization is automatically revoked when the associated temporal interval expires. The proposed model provides rules for the automatic derivation of new authorizations from those explicitly specified. Both positive and negative authorizations are supported. A formal definition of those concepts is presented, together with the semantic interpretation of authorizations and derivation rules as clauses of a general logic program. Issues deriving from the presence of negative authorizations are discussed. We also allow negation in rules: it is possible to derive new authorizations on the basis of the absence of other authorizations. The presence of this type of rule may lead to the generation of different sets of authorizations, depending on the evaluation order. An approach is presented, based on establishing an ordering among authorizations and derivation rules, which guarantees a unique set of valid authorizations. Moreover, we give an algorithm detecting whether such an ordering can be established for a given set of authorizations and rules. Administrative operations for adding, removing, or modifying authorizations and derivation rules are presented and efficiency issues related to these operations are also tackled in the paper. A materialization approach is proposed, allowing to efficiently perform access control     

Accountable privacy preserving attribute-based access control for cloud services enforced using blockchain

International Journal of Information Security - When dealing with cloud services, there are important security requirements that are highly recommended to be achieved, notably, access control....     

Reducing inference control to access control for normalized database schemas

Considering relational databases, controlled query evaluation preserves confidentiality even under inferences but at the expense of efficiency. Access control, however, enables efficiently computable access decisions but cannot automatically assure confidentiality because of missing inference control. In this paper we investigate constraints sufficient to eliminate (nontrivial) inferences in relational databases with the objective of replacing controlled query evaluation by access control mechanisms under preservation of confidentiality.     

网格服务及调用模型研究

开放网格服务体系结构（OGSA）是在Globus网格计算工具包和Web Service技术融合的基础上提出的一套规范和标准.OGSA以服务为中心,将一切都抽象为服务,网格服务是OGSA的基本概念.在介绍了网格服务的思想之后,分析了OGSA的架构体系,讨论了网格服务的组成以及典型标准接口的功能描述,研究了创建网格服务实例的过程,提出了一个网格服务调用模型,并对其处理过程进行了描述.     

面向服务网格的访问控制模型研究

建立以网格服务为中心的访问控制模型,通过集中式的管理来降低网格环境中访问控制复杂性,将角色网格服务的分配和服务的访问授权分离管理,能够有效地保护资源拥有者的权限.在中国科学院e-science科学数据网格项目中的初步应用实施表明了该模型的灵活性和有效性.     

基于证书的语义Web服务访问控制方法

为了实现语义Web服务环境中的访问控制机制,研究了基于证书授权的访问控制方法.在对语义Web服务的访问控制需求进行分析的基础上,提出了将简单公钥基础设施/简单分布式安全基础设施(SPKI/SDSI)证书与OWL-S本体描述集成的访问控制方法,该方法将访问控制描述与服务功能描述集成在一个统一的框架中,既便于管理又提高了用户访问Web服务的效率.     

A relational database integrity framework for access control policies

Access control is one of the most common and versatile mechanisms used for information systems security enforcement. An access control model formally describes how to decide whether an access request should be granted or denied. Since the role-based access control initiative has been proposed in the 90s, several access control models have been studied in the literature. An access control policy is an instance of a model. It defines the set of basic facts used in the decision process. Policies must satisfy a set of constraints defined in the model, which reflect some high level organization requirements. First-order logic has been advocated for some time as a suitable framework for access control models. Many frameworks have been proposed, focusing mainly on expressing complex access control models. However, though formally expressed, constraints are not defined in a unified language that could lead to some well-founded and generic enforcement procedures. Therefore, we make a clear distinction by proposing a logical framework focusing primarily on constraints, while keeping as much as possible a unified way of expressing constraints, policies, models, and reference monitors. This framework is closely tied to relational database integrity models. We then show how to use well-founded procedures in order to enforce and check constraints. Without requiring any rewriting previous to the inference process, these procedures provide clean and intuitive debugging traces for administrators. This approach is a step toward bridging the gap between general but hard to maintain formalisms and effective but insufficiently general ones.     

授权与访问控制策略模型的研究

针对现有授权与访问控制系统大规模、跨地域、分布式、多应用的发展趋势,在分析系统中策略分类和策略管理的作用的基础上,从策略之间的约束关系和策略作用范围的角度出发,创建了适应分布式环境的策略层次、策略作用域模型。     

Patient-centric authorization framework for electronic healthcare services

In modern healthcare environments, a fundamental requirement for achieving continuity of care is the seamless access to distributed patient health records in an integrated and unified manner, directly at the point of care. However, Electronic Health Records (EHRs) contain a significant amount of sensitive information, and allowing data to be accessible at many different sources increases concerns related to patient privacy and data theft. Access control solutions must guarantee that only authorized users have access to such critical records for legitimate purposes, and access control policies from distributed EHR sources must be accurately reflected and enforced accordingly in the integrated EHRs. In this paper, we propose a unified access control scheme that supports patient-centric selective sharing of virtual composite EHRs using different levels of granularity, accommodating data aggregation and privacy protection requirements. We also articulate and address issues and mechanisms on policy anomalies that occur in the composition of discrete access control policies from different data sources.     

Presto authorization: a bitmap indexing scheme for high-speed access control to XML documents

XML (extensible markup language) is fast becoming the de facto standard for information exchange over the Internet. As more and more sensitive information gets stored in the form of XML, proper access control to the XML documents becomes increasingly important. However, traditional access control methodologies that have been adapted for XML documents do not address the performance issue of access control. This paper proposes a bitmap-indexing scheme in which access control decisions can be sped up. Authorization policies of the form (subject, object, and action) are encoded as bitmaps in the same manner as XML document indexes are constructed. These two are then efficiently pipelined and manipulated for "fast" access control and "secure" retrieval of XML documents.