Common Representation of Information Flows for Dynamic Coalitions

We propose a formal foundation for reasoning about access control policies within a Dynamic Coalition, defining an abstraction over existing access control models and providing mechanisms for translation of those models into information-flow domain. The abstracted information-flow domain model, called a Common Representation, can then be used for defining a way to control the evolution of Dynamic Coalitions with respect to information flow

An algebraic basis for specifying and enforcing access control in security systems

Security services in a multi-user environment are often based on access control mechanisms. Static aspects of an access control policy can be formalised using abstract algebraic models. We integrate these static aspects into a dynamic framework considering requesting access to resources as a process aiming at the prevention of access control violations when a program is executed. We use another algebraic technique, monads, as a meta-language to integrate access control operations into a functional programming language. The integration of monads and concepts from a denotational model for process algebras provides a framework for programming of access control in security systems

Dynamic User Role Assignment in Remote Access Control

The Role-Based Access Control (RBAC) model has been widely applied to a single domain in which users are known to the administrative unit of that domain, beforehand. However, the application of the conventional RBAC model for remote access control scenarios is not straightforward. In such scenarios, the access requestor is outside of the provider domain and thus, the user population is heterogeneous and dynamic. Here, the main challenge is to automatically assign users to appropriate roles of the provider domain. Trust management has been proposed as a supporting technique to solve the problem of remote access control. The key idea is to establish a mutual trust between the requestor and provider based on credentials they exchange. However, a credential doesn't convey any information about the behavior of its holder during the time it is being used. Furthermore, in terms of privileges granted to the requestor, existing trust management systems are either too restrictive or not restrictive enough. In this paper, we propose a new dynamic user-role assignment approach for remote access control, where a stranger requests for access from a provider domain. Our approach has two advantages compared to the existing dynamic user-role assignment techniques. Firstly, it addresses the principle of least privilege without degrading the efficiency of the access control system. Secondly, it takes into account both credentials and the past behavior of the requestor in such a way that he cannot compensate for the lack of necessary credentials by having a good past behavior

A Dynamic Access Control Model Using Authorising Workfow and Task Role-based Access Control

Access control is fundamental and prerequisite to govern and safeguard information assets within an organisation. Organisations generally use Web enabled remote access coupled with applications access distributed across various networks. These networks face various challenges including increase operational burden and monitoring issues due to the dynamic and complex nature of security policies for access control. The increasingly dynamic nature of collaborations means that in one context a user should have access to sensitive information, whilst not being allowed access in other contexts. The current access control models are static and lack Dynamic Segregation of Duties (SoD), Task instance level of Segregation, and decision making in real time. This thesis addresses these limitations describes tools to support access management in borderless network environments with dynamic SoD capability and real time access control decision making and policy enforcement. This thesis makes three contributions: i) Defining an Authorising Workflow Task Role Based Access Control (AW-TRBAC) using existing task and workflow concepts. This new workflow integrates dynamic SoD, whilst considering task instance restriction to ensure overall access governance and accountability. It enhances existing access control models such as Role Based Access Control (RBAC) by dynamically granting users access rights and providing access governance. ii) Extension of the OASIS standard of XACML policy language to support dynamic access control requirements and enforce access control rules for real time decision making. This mitigates risks relating to access control, such as escalation of privilege in broken access control, and insucient logging and monitoring. iii) The AW-TRBAC model is implemented by extending the open source XACML (Balana) policy engine to demonstrate its applicability to a real industrial use case from a financial institution. The results show that AW-TRBAC is scalable, can process relatively large numbers of complex requests, and meets the requirements of real time access control decision making, governance and mitigating broken access control risk

Towards a Formal Model of Privacy-Sensitive Dynamic Coalitions

The concept of dynamic coalitions (also virtual organizations) describes the temporary interconnection of autonomous agents, who share information or resources in order to achieve a common goal. Through modern technologies these coalitions may form across company, organization and system borders. Therefor questions of access control and security are of vital significance for the architectures supporting these coalitions. In this paper, we present our first steps to reach a formal framework for modeling and verifying the design of privacy-sensitive dynamic coalition infrastructures and their processes. In order to do so we extend existing dynamic coalition modeling approaches with an access-control-concept, which manages access to information through policies. Furthermore we regard the processes underlying these coalitions and present first works in formalizing these processes. As a result of the present paper we illustrate the usefulness of the Abstract State Machine (ASM) method for this task. We demonstrate a formal treatment of privacy-sensitive dynamic coalitions by two example ASMs which model certain access control situations. A logical consideration of these ASMs can lead to a better understanding and a verification of the ASMs according to the aspired specification.Comment: In Proceedings FAVO 2011, arXiv:1204.579

Random Access Game and Medium Access Control Design

Motivated partially by a control-theoretic viewpoint, we propose a game-theoretic model, called random access game, for contention control. We characterize Nash equilibria of random access games, study their dynamics, and propose distributed algorithms (strategy evolutions) to achieve Nash equilibria. This provides a general analytical framework that is capable of modeling a large class of system-wide quality-of-service (QoS) models via the specification of per-node utility functions, in which system-wide fairness or service differentiation can be achieved in a distributed manner as long as each node executes a contention resolution algorithm that is designed to achieve the Nash equilibrium. We thus propose a novel medium access method derived from carrier sense multiple access/collision avoidance (CSMA/CA) according to distributed strategy update mechanism achieving the Nash equilibrium of random access game. We present a concrete medium access method that adapts to a continuous contention measure called conditional collision probability, stabilizes the network into a steady state that achieves optimal throughput with targeted fairness (or service differentiation), and can decouple contention control from handling failed transmissions. In addition to guiding medium access control design, the random access game model also provides an analytical framework to understand equilibrium and dynamic properties of different medium access protocols

Securing Controls Middleware of the Large Hadron Collider

The distributed control system of the Large Hadron Collider (LHC) presents many challenges due to its inherent heterogeneity and highly dynamic nature. One critical challenge is providing access control guarantees within the middleware. Role-based access control (RBAC) is a good candidate to provide access control. However, in an equipment control system transactions are often dependent on user context and device context. Unfortunately, classic RBAC cannot be used to handle the above requirements. In this paper we present an extended role-based access control model called CMW-RBAC. This new model incorporates the advantages of role-based permission administration together with a fine-grained control of dynamic context attributes. We also propose a new technique called dynamic authorization that allows phased introduction of access control in large distributed systems. This paper also describes motivation of the project, requirements, and overview of its main components: authentication and authorization

A Game-Theoretic Framework for Medium Access Control

In this paper, we generalize the random access game model, and show that it provides a general game-theoretic framework for designing contention based medium access control. We extend the random access game model to the network with multiple contention measure signals, study the design of random access games, and analyze different distributed algorithms achieving their equilibria. As examples, a series of utility functions is proposed for games achieving the maximum throughput in a network of homogeneous nodes. In a network with n traffic classes, an N-signal game model is proposed which achieves the maximum throughput under the fairness constraint among different traffic classes. In addition, the convergence of different dynamic algorithms such as best response, gradient play and Jacobi play under propagation delay and estimation error is established. Simulation results show that game model based protocols can achieve superior performance over the standard IEEE 802.11 DCF, and comparable performance as existing protocols with the best performance in literature