]> 2005-05-06T12:30:00-05:00 REI developed at University of Maryland Baltimore County is an expressive and extensible language for describing different kinds of policies in a wide range of application domains such as security policies / privacy policies. The REI policy engine reasons over REI policies and domain knowledge to provide answers about current permissions and obligations of an entity dynamically. REI allows the dynamic change of policies on the fly through its provision of speech acts such as delegation.

Using Task Computing as a platform we have shown that REI can be used in highly pervasive and ubiquitous environments to provide access control decisions. These decisions are based on facts provided by the client, resource/service policies, shared policies and ontologies depicting the domain knowledge of the organization. In addition XML Digital Signatures are used to provide authentication and data integrity.]]>