A trust implementation model for cross-domain decentralized identity ecosystems

Managing interoperable trust across different domains – as required for a wide adoption of decentralized / self-sovereign identities (SSI) leveraging verifiable credentials - remains a challenge. Verifiable credentials are a part of numerous international and European initiatives like the EUDI Wallet, EBSI, and Gaia-X to enable sovereign data sharing. Nevertheless, a standardized reference framework addressing interoperability challenges around trust in cross-domain environments based on decentralized identities is missing and is one factor hindering wider adoption. To facilitate the interoperability of credentials across borders and organizations this paper proposes a new trust implementation model architecture that enables credentials issued by different entities to be shared and verified in a trustworthy manner. This implementation model architecture also contains a novel unified signature and verification model for the trust list. A use case and implementation details for the model are presented. Furthermore, it discusses potential integration possibilities with existing initiatives using the proposed architecture.