Private digital identity on blockchain

Abstract

For many identification systems, including those in government, finance and healthcare, it is critical that at most one identity exists for each human individual within a given system. Many existing approaches identify individuals through an exchange of verifiable documents attesting to basic identification information. However, the same basic information is collected for identification in almost every system, meaning that persons are linkable across different identity systems and are not in control of how their identity is used. We propose Unique Self-Sovereign Identity, (USI), combining Cancelable Biometrics [6] and W3C Verifiable Claims [8] to achieve privacy preserving and non-linkable identification, with guarantees against double enrolment with any system. Because our protocol is based on biometrics, it permits individuals to enrol without official identification documents. Our protocol can be used in a wide range of situations, offering data security for large organisations, access to basic services for over one billion people who lack official identifying documents, and personal identity control for all individuals.