Improved Policy Database System for Protecting Possession Sensitive Attributes in Automated Trust Negotiation

Automated trust negotiation is an iterative process that establishes trust gradually between strangers wishing to share resources or conduct business transactions, by requesting and disclosing digital credentials. Protection of sensitive information in automated trust negotiation has been drawn much attention all over the world. Recently, policy database has been proposed as a means to protect possession-sensitive attributes. However, possession sensitive information leakage through probabilistic inference still exists in it. In order to solve this problem, in this paper, a formal definition for relevant attributes is given. A relation model of relevant attributes is also designed. Besides that, we present a desideratum of policies for relevant attributes based on the relation model. And the desideratum is enforced in a relevance checker that is used to check whether the submitted policies satisfy the desideratum, which is an addition to the policy database system as an improvement. Safety in this improved policy database system is analyzed, which comes to a conclusion that this approach, compared with the original policy database system, provides more strongly protection to possession sensitive attributes.