A Decentralized Identity Bridge for Usable Blockchain-backed Self-Sovereign Identity

The emergence of public permissionless blockchains has increased awareness of privacy issues
and the risks associated with centralization. This has likely contributed to the development of
Self-Sovereign Identity (SSI) as a new paradigm in identity management, offering enhanced
user control and data ownership through the issuance of Verifiable Credentials (VC). VCs can
be stored in specialized mobile wallet apps and can be used to generate Verifiable Presentations
(VP) that prove claims to a relying party.
Simple logins are the foundation of today’s Internet and largely centralized. Blockchain
communities have already explored decentralized solutions such as Sign-in With Ethereum and
connections to established identity and access management (IAM). However, these solutions are
locked into specific ecosystems and thus limited in their capabilities and interoperability. An SSI
ecosystem with single-sign-on (SSO) support for easy transitions and backward compatibility
can provide decentralized identity management that is a genuine alternative for a significant part
of contemporary systems, providing them with not just a blockchain address but a customizable
set of further attributes.
Existing contributions by Grüner et al. propose a multiplexing system between different
SSI vendors and various IAM protocols. However, their solution is complex because it combines
sign-in and VC issuance. In addition, the SSI protocol landscape has considerably shifted.
Seeing that no such system has gained traction yet, we design and implement a proof of
concept toward SSI-enabled SSO with respect to SSI principles and real-world usability.