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Handbook on Mobile and Ubiquitous Computing: Status and Perspective
Covington et al. proposed the concept of environment roles in order to develop an access control
system for pervasive computing that can utilize environmental and contextual information [18].
Environment roles are in essence one component of the Generalized Role-Based Access Control
(GRBAC) model [19]. GRBAC is an extension of the traditional RBAC model where object
and environment roles are defined in addition to subject roles. The resources provided in an
environment can be assigned to object roles and environmental (contextual) conditions are used
to define environment roles. GRBAC uses a logic language similar to Prolog to express access
control constraints on context variables. ...