Point-based trust: Define how much privacy is worth

Abstract

This paper studies the notion of point-based policies for trust management, and gives protocols for realizing them in a disclosure-minimizing fashion. Specifically, Bob values each credential with a certain number of points, and requires a minimum total threshold of points before granting Alice access to a resource. In turn, Alice values each of her credentials with a privacy score that indicates her reluctance to reveal that credential. Bob’s valuation of credentials and his threshold are private. Alice’s privacy-valuation of her credentials is also private. Alice wants to find a subset of her credentials that achieves Bob’s required threshold for access, yet is of as small a value to her as possible. We give protocols for computing such a subset of Alice’s credentials without revealing any of the two parties’ above-mentioned private information.