Roshan K. Thomas

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In this paper, we develop a new paradigm for access control and authorization management, called task-based authorization controls (TBAC). TBAC models access controls from a task-oriented perspective than the traditional subject-object one. Access mediation now involves authorizations at various points during the completion of tasks in accordance with some(More)
In this paper, we introduce the notion of TeaM-based Access Control (TMAC) as an approach to applying rolebased access control in collaborative environments. Our focus is on collaborative activity that is best accomplished through organized teams. Thus, central to the TMAC approach is the notion of a “team” as an abstraction that encapsulates a collection(More)
We discuss the integration of contextual information with team-based access control. The TMAC model was formulated by Thomas in [1] to provide access control for collaborative activity best accomplished by teams of users. In TMAC, access control revolves around teams, where a "team" is an abstraction that encapsulates a collection of users in specific roles(More)
In this paper, we develop a new paradigm for access control and authorization management, called task-based authorization controls (TBAC). TBAC models access controls from a task-oriented perspective than the traditional subject-object one. Access mediation now involves authorizations at various points during the completion of tasks in accordance with some(More)
In mobile ad hoc networks (MANETs), a source node must rely on other nodes to forward its packets on multi-hop routes to the destination. Secure and reliable handling of packets by the intermediate nodes is difficult to ensure in an ad hoc environment. We propose a trust establishment scheme for MANETs which aims to improve the reliability of packet(More)
To effectively participate in modern coalitions, member organizations must be able to share specific data and functionality with coalition partners, while ensuring that their resources are safe from inappropriate access. This requires access control models, policies, and enforcement mechanisms for coalition resources. This paper describes a family of(More)
In a mobile ad hoc network (MANET), a source node must rely on intermediate nodes to forward its packets along multi-hop routes to the destination node. Due to the lack of infrastructure in such networks,secure and reliable packet delivery is diffocult to achieve. We propose a robust cooperative trust establishment scheme to improve the reliability of(More)
We describe "NetBouncer", an approach and set of technologies for providing practical and highperformance defenses against distributed denial-ofservice (DDoS) attacks. The central innovation in the NetBouncer approach to filtering and mitigating DDoS attacks is the ability to distinguish legitimate traffic from illegitimate ones so as to enable the(More)
In a mobile ad hoc network (MANET), a source node must rely on intermediate nodes to forward its packets along multi-hop routes to the destination node. Due to the lack of infrastructure in such networks, secure and reliable packet delivery is challenging. We propose a robust cooperative trust establishment scheme to improve the reliability of packet(More)