Supporting Privacy with Zero Knowledge in SSI and Blockchain based Access Control, Laura Ricci

Talk by Laura Ricci (University of Pisa)
Abstract:
Recent years have witnessed, especially in Europe, a shift aimed at bringing users back at the center of digital systems. This has driven innovation towards the affirmation of decentralized systems, in line with the Self Sovereign Identity paradigm. User control over the consumption and disclosure of their data is a key topic of such drive. This talk will discuss how it is possible to apply this increasingly popular concept to a traditionally centralized and opaque digital process: Access Control systems. In particular, we will show how to expand the XACML standard for Attribute Based Access Control systems with the novel concept of private attributes, i.e. attributes whose values should not be disclosed while still contributing to a policy evaluation result after user consent. The system is based on blockchain systems, and leverages smart contracts and zero knowledge proofs to allow for transparent policies evaluation without disclosing the value of such sensible attributes.