Role-based access control is an important way of limiting the access users have to computing resources. While the basic concepts of role-based access control are now well understood, there is no consensus on the best approach to managing role-based systems. In this paper, we introduce a new model for role-based administration, using the notions of discretionary and mandatory controls. Our model...

The Role-Based Access Control (RBAC) model is traditionally used to manually assign users to appropriate roles, based on a specific enterprise policy, thereby authorizing them to use the roles' permissions. In environments where the service-providing enterprise has a huge customer base this task becomes formidable. An appealing solution is to automatically assign users to roles. The central con...

The paper presents revocation schemes in role-based access control models. We are particularly interested in two key issues: how to perform revocation and how to manage the revocation policy. We show how to deal with these two aspects in the delegation model based on the OrBAC formalism and its administration licence concept. This model provides means to manage several delegation types, such as...

We demonstrate how access control models and policies can be represented by using term rewriting systems, and how rewriting may be used for evaluating access requests and for proving properties of an access control policy. We focus on two kinds of access control models: discretionary models, based on access control lists (ACLs), and rolebased access control (RBAC) models. For RBAC models, we sh...

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 ...

This chapter surveys network-level approaches to conserve energy in sensor networks. We consider protocols for transmission power control, media access control, topology control, and energy-aware routing, surveying relevant literature and describing approaches that have been considered.

We present a framework for studying the problem of media streaming in technology and cost heterogeneous environments. We first address the problem of efficient streaming in a technologyheterogeneous setting. We employ random linear network coding to simplify the packet selection strategies and alleviate issues such as duplicate packet reception. Then, we study the problem of media streaming fro...

With the increasing amount of mobile interfaces combining different kinds of access technologies, ranging from Wi-Fi to 3G and LTE, the integration of flexible and mediaindependent link control mechanisms becomes of paramount importance. By employing an abstract way of obtaining access link status information and exercising control over the network interface operations, these control mechanisms...