A Card Requirements Language Enabling Privacy-Preserving Access Control

We address the problem of privacy-preserving access control in distributed systems. Users commonly reveal more personal data than strictly necessary to be granted access to online resources, even though existing technologies, such as anonymous credential systems, offer functionalities that would allow for privacy-friendly authorization. An important reason for this lack of technology adoption is, as we believe, the absence of a suitable authorization language offering adequate expressiveness to address the privacy-friendly functionalities. To overcome this problem, we propose an authorization language that allows for expressing access control requirements in a privacy-preserving way. Our language is independent from concrete technology, thus it allows for specifying requirements regardless of implementation details while it is also applicable for technologies designed without privacy considerations. We see our proposal as an important step towards making access control systems privacy-preserving.