Separation of duties is an important, real-world requirement that access control models should support. In [13], Sandhu introduced the transaction control expression (TCE) for specifying dynamic separation of duties. In this paper we consider the implementation of TCEs in the typed access matrix model (TAM) recently proposed by Sandhu [16]. We show that TAM requires extension for satisfactory h...

The universal adoption of the Internet requires a fine grained access control in the sharing of sensitive resources. However, existing access control mechanisms are inflexible and do not help in alleviating the management task of administrating users’ access to resources based on security policies. In this paper, we propose an approach to implement fine-grained access control based on RBAC whil...

Flexibility of management is an important requisite for access control systems as it allows users to adapt the access control system in accordance with practical requirements. This paper builds on earlier work where we defined administrative policies for a general class of RBAC models. We present a formal definition of administrative refinement and we show that there is an ordering for administ...

Access control administration regulates and enforces the definition of the components of an access control system by authorized administrative users. In this paper, the limitations on administrative aspects of well-known security models are addressed and the requirements for efficient management of authorizations are investigated in order to provide fine-grained and just-in-time access control ...

Research in the area of role-based access control has made fast progress over the last few years. However, little has been done to identify and describe existing role-based access control systems within large organisations. This paper describes the access control system of a major European Bank. An overview of the system’s structure, its administration and existing control principles constraini...

extensive researches on wireless sensor networks (wsns) have been performed and many techniques have been developed for the data link (mac) layer. most of them assume single-channel mac protocols. in the usual dense deployment of the sensor networks, single-channel mac protocols may be deficient because of radio collisions and limited bandwidth. hence, using multiple channels can significantly ...