This is an idea proposed in 2022 as a Cambridge Computer Science Part II project, and has been completed by Michał Mgeładze-Arciuch. It was supervised by Anil Madhavapeddy and Patrick Ferris as part of my Interspatial OS project.
There are currently multiple identity providers without direct incentives to cooperate. This leads to many redundant implementations of the identity handling logic, many of which are not immediately compatible with each other, leading to additional increases in friction when eventual agreement needs to be reached to perform user actions. Furthermore, from the perspective of the user of the identity service, they need to keep track of identity documents from multiple sources, which leads to more security attack surface.
Solving the problem of partial identity proofs allows for many possible opportunities. For example, consider a simple May Ball ticketing system in which every college member gets a discount to their College, but without revealing their exact identity. Or imagine an e-commerce system, in which every user could prove their age to be over a given threshold, without revealing any additional information to the retailer. In the example of a carbon credits project, we would be able to allow entities associated with any carbon offsetting project to prove their association, protecting the identity of whistleblowers.
This project will build a system of Decentralised Digital Identifiers, which can be used to prove a subset of the information associated with the user’s identity using cryptographic proofs. Every participant in the system will have a public-private key pair associated with them. Then any identity provider P could provide an identity document for Alice, who has a public key A, by cryptographically signing a message containing both A, to point to the receiver of this document, and the document itself. Then, whenever Alice would want to authenticate herself to a service provider S, she could do so simply by sending the message she received from P to S. Then the service provider can verify that P, indeed supplied Alice with the given identity document.
This Part II project was successfully completed but not available online; please contact the author for a copy of it. Michał Mgeładze-Arciuch has subsequently founded Yoneda Labs to revolutionize chemical reactions!