Privacy Preserving Trust Authorization Framework Using XACML

Nowadays many organisations share sensitive services through open network systems and this raises the need for an authorization framework that can interoperate even when the parties have no pre-existing relationships. Trust Negotiation is the process used to establish these first relationships, through the transfer of attributes, embedded in digital credentials, between the two parties. However, these attributes may themselves be considered sensitive and so may need protection from disclosure. In some environments, the policies that govern the protected services may also be considered sensitive and their release to arbitrary strangers may leak confidential business information. Thus, the electronic services, the policies that control access to them, and the digital credentials used to gain access may all be sensitive and require access protections. This paper describes how to unify the protection of services, sensitive credentials and policies in a synchronised trustworthy manner. We propose a trust authorization framework (TAF) that builds on the capabilities of XACML to support the bilateral exchange of policies and credentials through trust negotiation. Our framework addresses privacy and trust issues, and considers services, credentials, and authorization policies protected resources whose access is subject to credential proof and trust level validation