A secure, constraint-aware role-based access control interoperation framework

With the growing needs for and the benefits of sharing resources and information among different organizations, an interoperation framework that automatically integrates policies to facilitate such cross-domain sharing in a secure way is becoming increasingly important. To avoid security breaches, such policies must enforce the policy constraints of the individual domains. Such constraints may include temporal constraints that limit the times when the users can access the resources, and separation of duty (SoD) constraints. Existing interoperation solutions do not address such cross-domain temporal access control and SoDs requirements. In this paper, we propose a role-based framework to facilitate secure interoperation among multiple domains by ensuring the enforcement of temporal and SoD constraints of individual domains. To support interoperation, we do not modify the internal policies, as most of the current approaches do. We present experimental results to demonstrate our proposed framework is effective and easily realizable. © 2011 IEEE

On the Security of Delegation in Access Control Systems

Abstract. Delegation is a mechanism that allows a user A to act on another user B’s behalf by making B’s access rights available to A. It is well recognized as an important mechanism to provide resiliency and flexibility in access control systems, and has gained popularity in the research community. However, most existing literature focuses on modeling and managing delegations. Little work has been done on understanding the impact of delegation on the security of existing access control systems. In particular, no formal notion of security with respect to delegation has been proposed. Many existing access control systems are designed without having delegation in mind. Simply incorporating a delegation module into those systems may cause security breaches. This paper focuses on the security aspect of delegation in access control systems. We first give examples on how colluding users may abuse the delegation sup-port of access control systems to circumvent security policies, such as separation of duty. As a major contribution, we propose a formal notion of security with respect to delegation in access control systems. After that, we discuss potential mechanisms to enforce security. In particular, we design a novel source-based en-forcement mechanism for workflow authorization systems so as to achieve both security and efficiency.

Fine-grained role-based delegation in presence of the hybrid role hierarchy

Delegation of authority is an important process that needs to be captured by any access control model. In role-based access control models, delegation of authority involves delegating roles that a user can assume or the set of permissions that he can acquire, to other users. Several role-based delegation models have been proposed in the literature. However, these models consider delegation in presence of the general hierarchy type. Multiple hierarchy types have been proposed in the context of Generalized Temporal Role-based Access Control (GTRBAC) model, where it has been shown that multiple hierarchy semantics is desirable to express fine-grained access control policies. In this paper, we address role-based delegation schemes in the of hybrid hierarchies and elaborate on fine-grained delegation schemes. In particular, we show that upward delegation, which has been considered as having no practical use, is a desirable feature. Furthermore, we show that accountability must be considered as an important factor during the delegation process. The delegation framework proposed subsumes delegations schemes proposed in earlier role-based delegation models and provide much more fine-grained control of delegation semantics

Fine-grained role-based delegation in presence of the hybrid role hierarchy

Delegation of authority is an important process that needs to be captured by any access control model. In role-based access control models, delegation of authority involves delegating roles that a user can assume or the set of permissions that he can acquire, to other users. Several role-based delegation models have been proposed in the literature. However, these models consider delegation in presence of the general hierarchy type. Multiple hierarchy types have been proposed in the context of Generalized Temporal Role-based Access Control (GTRBAC) model, where it has been shown that multiple hierarchy semantics is desirable to express fine-grained access control policies. In this paper, we address role-based delegation schemes in the of hybrid hierarchies and elaborate on fine-grained delegation schemes. In particular, we show that upward delegation, which has been considered as having no practical use, is a desirable feature. Furthermore, we show that accountability must be considered as an important factor during the delegation process. The delegation framework proposed subsumes delegations schemes proposed in earlier rolebased delegation models and provide much more fine-grained control of delegation semantics

Access Control Administration with Adjustable Decentralization

Access control is a key function of enterprises that preserve and propagate massive data. Access control enforcement and administration are two major components of the system. On one hand, enterprises are responsible for data security; thus, consistent and reliable access control enforcement is necessary although the data may be distributed. On the other hand, data often belongs to several organizational units with various access control policies and many users; therefore, decentralized administration is needed to accommodate diverse access control needs and to avoid the central bottleneck. Yet, the required degree of decentralization varies within different organizations: some organizations may require a powerful administrator in the system; whereas, some others may prefer a self-governing setting in which no central administrator exists, but users fully manage their own data. Hence, a single system with adjustable decentralization will be useful for supporting various (de)centralized models within the spectrum of access control administration. Giving individual users the ability to delegate or grant privileges is a means of decentralizing access control administration. Revocation of arbitrary privileges is a means of retaining control over data. To provide flexible administration, the ability to delegate a specific privilege and the ability to revoke it should be held independently of each other and independently of the privilege itself. Moreover, supporting arbitrary user and data hierarchies, fine-grained access control, and protection of both data (end objects) and metadata (access control data) with a single uniform model will provide the most widely deployable access control system. Conflict resolution is a major aspect of access control administration in systems. Resolving access conflicts when deriving effective privileges from explicit ones is a challenging problem in the presence of both positive and negative privileges, sophisticated data hierarchies, and diversity of conflict resolution strategies. This thesis presents a uniform access control administration model with adjustable decentralization, to protect both data and metadata. There are several contributions in this work. First, we present a novel mechanism to constrain access control administration for each object type at object creation time, as a means of adjusting the degree of decentralization for the object when the system is configured. Second, by controlling the access control metadata with the same mechanism that controls the users’ data, privileges can be granted and revoked to the extent that these actions conform to the corporation’s access control policy. Thus, this model supports a whole spectrum of access control administration, in which each model is characterized as a network of access control states, similar to a finite state automaton. The model depends on a hierarchy of access banks of authorizations which is supported by a formal semantics. Within this framework, we also introduce the self-governance property in the context of access control, and show how the model facilitates it. In particular, using this model, we introduce a conflict-free and decentralized access control administration model in which all users are able to retain complete control over their own data while they are also able to delegate any subset of their privileges to other users or user groups. We also introduce two measures to compare any two access control models in terms of the degrees of decentralization and interpretation. Finally, as the conflict resolution component of access control models, we incorporate a unified algorithm to resolve access conflicts by simultaneously supporting several combined strategies

Analyzing and developing role-based access control models

Role-based access control (RBAC) has become today's dominant access control model, and many of its theoretical and practical aspects are well understood. However, certain aspects of more advanced RBAC models, such as the relationship between permission usage and role activation and the interaction between inheritance and constraints, remain poorly understood. Moreover, the computational complexity of some important problems in RBAC remains unknown. In this thesis we consider these issues, develop new RBAC models and answer a number of these questions. We develop an extended RBAC model that proposes an alternative way to distinguish between activation and usage hierarchies. Our extended RBAC model has well-defined semantics, derived from a graph-based interpretation of RBAC state. Pervasive computing environments have created a requirement for access control systems in which authorization is dependent on spatio-temporal constraints. We develop a family of simple, expressive and flexible spatio-temporal RBAC models, and extend these models to include activation and usage hierarchies. Unlike existing work, our models address the interaction between spatio-temporal constraints and inheritance in RBAC, and are consistent and compatible with the ANSI RBAC standard. A number of interesting problems have been defined and studied in the context of RBAC recently. We explore some variations on the set cover problem and use these variations to establish the computational complexity of these problems. Most importantly, we prove that the minimal cover problem -- a generalization of the set cover problem -- is NP-hard. The minimal cover problem is then used to determine the complexity of the inter-domain role mapping problem and the user authorization query problem in RBAC. We also design a number of efficient heuristic algorithms to answer the minimal cover problem, and conduct experiments to evaluate the quality of these algorithms.EThOS - Electronic Theses Online ServiceGBUnited Kingdo