Dependencies and Separation of Duty Constraints in GTRBAC

A Generalized Temporal Role Based Access Control (GTRBAC) model that captures an exhaustive set of temporal constraint needs for access control has recently been proposed. GTRBAC’s language constructs allow one to specify various temporal constraints on role, user-role assignments and role-permission assignments. In this paper, we identify various time-constrained cardinality, control flow dependency and separation of duty constraints (SoDs). Such constraints allow specification of dynamically changing access control requirements that are typical in today’s large systems. In addition to allowing specification of time, the constraints introduced here also allow expressing access control policies at a finer granularity. The inclusion of control flow dependency constraints allows defining much stricter dependency requirements that are typical in workflow types of applications

Security challenges in adaptive e-Health processes

E-health scenarios demand system-based support of process-oriented information systems. As most of the processes in this domain have to be flexibly adapted to meet exceptional or unforeseen situations, flexible process-oriented information systems (POIS) are needed which support ad-hoc deviations at the process instance level. However, e-health scenarios are also very sensitive with regard to privacy issues. Therefore, an adequate access rights management is essential as well. The paper addresses challenges which occur when flexible POIS and adequate rights management have to be put together

Context Sensitive Access Control Model TI for Business Processes

Kontrola pristupa odnosno autorizacija, u širem smislu, razmatra na koji način korisnici mogu pristupiti resursima računarskog sistema i na koji način ih koristiti. Ova disertacija se bavi problemima kontrole pristupa u poslovnim sistemima. Tema disertacije je formalna specifkacija modela kontekstno zavisne kontrole pristupa u poslovnim sistemima koji je baziran na RBAC modelu kontrole pristupa. Uvođenjem kontekstno zavisne kontrole pristupa omogućeno je defnisanje složenijih prava pristupa koje u postojećim modelima kontrole pristupa za poslovne sisteme nije bilo moguće realizovati ili bi njihova realizacija bila komplikovana. Dati model primenljiv je u različitim poslovnim sistemima, a podržava defnisanje prava pristupa kako za jednostavne tako i za slo·zene poslovne tokove. Sistem je verifkovan na dva realna poslovna procesa pomoću razvijenog prototipa. Prikazana prototipska implementacija koja ispunjava ciljeve u pogledu funkcionalnosti postavljene pred sistem predstavlja potvrdu praktične vrednosti predloženog modela.Access control is concerned with the way in which users can access to resources in the computer system. This dissertation focuses on problems of access control for business processes. The subject of the dissertation is a formal specification of the RBAC-based context sensitive access control model for business processes. By using a context-sensitive access control it is possible to define more complex access control policies whose implementation in existing access control models for business processes is not possible or is very complicated. The given model is applicable in diferent business systems, and supports the definition of access control policies for both simple and complex business processes. The model's prototype is verified by two case studies on real business processes. The presented prototype implementation represents a proof of the proposed model's practical value

Approches formelles pour la modélisation et la vérification du contrôle d'accès et des contraintes temporelles dans les systèmes d'information

RÉSUMÉ Nos travaux de recherche s’inscrivent dans un cadre qui vise à développer des approches formelles pour aider à concevoir des systèmes d’information avec un bon niveau de sûreté et de sécurité. Précisément, il s’agit de disposer d’approches pour vérifier qu’un système fonctionne correctement et qu’il implémente une politique de sécurité qui répond à ses besoins spécifiques en termes de confidentialité, d’intégrité et de disponibilité des données. Notre recherche s’est ainsi construite autour de la volonté de développer, valoriser et élargir l’utilisation des réseaux de Petri en tant qu’outil de modélisation et le model-checking en tant que technique de vérification. Notre principal objectif est d’exprimer la dimension temporelle de manière quantitative pour vérifier des propriétés temporelles telles que la disponibilité des données, la durée d’exécution des tâches, les deadlines, etc. Tout d’abord, nous proposons une extension du modèle TSCPN (Timed Secure Colored Petri Net), initialement présenté dans mon mémoire de maˆıtrise. Le modèle TSCPN permet de modéliser et de raisonner sur les droits d’accès aux données exprimés via une politique de contrôle d’accès mandataire, i.e. Modèle de Bell-LaPadula. Ensuite, nous investigons l’idée d’utiliser les réseaux de Petri colorés pour représenter les politiques de contrôle d’accès à base de rôles (Role Based Access Control - RBAC). Notre objectif est de fournir des guides précis pour aider à la spécification d’une politique RBAC cohérente et complète, appuyée par les réseaux de Petri colorés et l’outil CPNtools. Finalement, nous proposons d’enrichir la classe des réseaux de Petri temporels par une nouvelle extension qui permet d’exprimer plus d’un seul type de contraintes temporelles. Il s’agit du modèle TAWSPN (Timed Arc Petri net - Weak and Strong semantics). Notre but étant d’offrir une grande flexibilité dans la modélisation de systèmes temporisés complexes sans complexifier les méthodes d’analyse classiques. En effet, le modèle TAWSPN offre une technique de modelchecking, basée sur la construction de graphes des zones (Gardey et al., 2003), comparables à celles des autres extensions temporelles des réseaux de Petri. ----------ABSTRACT Our research is integrated within a framework that aims to develop formal approaches to help in the design of information systems with a good level of safety and security. Specifically, these approaches have to verify that a system works correctly and that it implements a security policy that meets its specific needs in terms of data confidentiality, integrity and availability. Our research is thus built around the aim to develop, enhance and expand the use of Petri nets as a modeling tool and the Model-checking as a verification technique. Our main objective is to express the temporal dimension in order to check quantitative temporal properties such as data availability, task execution duration, deadlines, etc. First, we propose an extension of the TSCPN (Timed Secure Colored Petri Net) model, originally presented in my master’s thesis. This model allows representing and reasoning about access rights, expressed via a mandatory access control policy, i.e. Bell-LaPadula model. In a second step, we investigate the idea of using colored Petri nets to represent role based access control policies (RBAC). Our goal is to provide specific guidelines to assist in the specification of a coherent and comprehensive RBAC, supported by colored Petri nets and CPNtools. Finally, we propose to enrich the class of time Petri nets by a new extension that allows to express more than one kind of time constraint, named TAWSPN (Timed-Arc Petri net Weak and Strong semantics). Our goal is to provide great flexibility in modeling complex systems without complicating the conventional methods of analysis. Indeed, the TAWSPN model offers a model-checking technique based on the construction of zone graphs (Gardey et al., 2003), comparable to those of other extensions of timed Petri net

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

Extended role-based access control model for enterprise systems and web services

This thesis intends to develop application-level access control models to address several major security issues in enterprise environments. The first goal is to provide simple and efficient authorization specifications to reduce the complexity of security management. The second goal is to provide dynamic access control for Web service applications. The third goal is to provide an access control framework for Semantic Web services. In this thesis, an Authorization-Function-Based Role-based Access Control (FB-RBAC) model is proposed for controlling enterprise systems at the application level. The unique features of the proposed model are authorization-function-based access control and constraint-based finegrained access control. This model significantly simplifies the management of an access control system by adopting roles and authorization-functions in authorization specifications. An extension of FB-RBAC, Extended FB-RBAC (ERBAC), is applied to Web service applications. New features such as credential-based access control and dynamic role assignment are added to FB-RBAC in order to address user heterogeneity and dynamicity in the Web environment. The proposed ERBAC model is then extended to support Semantic Web services. Each component of the ERBAC model is described by security ontologies. These correlated security ontologies are integrated with Semantic Web services to form a complete ontology network. Ontology-based role assignment is facilitated so that security information can be queries and discovered through a network of ontologies

Securely sharing dynamic medical information in e-health

This thesis has introduced an infrastructure to share dynamic medical data between mixed health care providers in a secure way, which could benefit the health care system as a whole. The study results of the universally data sharing into a varied patient information system prototypes

Multi-Tier Diversified Service Architecture for Internet 3.0: The Next Generation Internet

The next generation Internet needs to support multiple diverse application contexts. In this paper, we present Internet 3.0, a diversified, multi-tier architecture for the next generation Internet. Unlike the current Internet, Internet 3.0 defines a new set of primitives that allows diverse applications to compose and optimize their specific contexts over resources belonging to multiple ownerships. The key design philosophy is to enable diversity through explicit representation, negotiation and enforcement of policies at the granularity of network infrastructure, compute resources, data and users. The basis of the Internet 3.0 architecture is a generalized three-tier object model. The bottom tier consists of a high-speed network infrastructure. The second tier consists of compute resources or hosts. The third tier consists of data and users. The “tiered” organization of the entities in the object model depicts the natural dependency relationship between these entities in a communication context. All communication contexts, including the current Internet, may be represented as special cases within this generalized three-tier object model. The key contribution of this paper is a formal architectural representation of the Internet 3.0 architecture over the key primitive of the “Object Abstraction” and a detailed discussion of the various design aspects of the architecture, including the design of the “Context Router-” the key architectural element that powers an evolutionary deployment plan for the clean slate design ideas of Internet 3.0