20 Pages Posted: 20 May 2019

Date Written: April 20, 2019

Abstract

Most existing digital identity solutions are either centralized (e.g., national identity cards) or individualistic (e.g., most “self-sovereign” identity proposals). Outside of digital life, however, identity is typically social (for instance, “individual” data such as birthdate is shared with parents) and intersectional (viz., different data and trust are shared with different others). We formalize these ideas to provide a more robust and realistic framework for decentralized identity. We build upon the concepts web-of-trust and social collateral, from cryptography and economics, to provide a system of defining, verifying, and making use of identity through networks. We exploit the redundancy created by intersectionality together with the fragmentation of identity suggested by self-sovereign schemes to minimize social collateral required for verification. We exploit the probabilistic structure of Bloom filters to provide uniqueness proofs to prevent Sybil attacks while conveying minimal compromising information to verifiers. We discuss applications to “proof-of-personhood” blockchains and Radical Markets.