Data spaces and self-sovereign identity: Ecosystem landscape and a systematic literature review on Gaia-X-aligned data spaces

Data spaces have emerged as a cornerstone of the European data strategy, aiming to enable secure, sovereign, and interoperable data sharing across sectors and borders. Within this vision, identity and credential management are fundamental to ensuring trust, compliance, and usability. Within the European context, Gaia-X is emerging as the fundamental trust framework for data spaces. However, the complexity of the data spaces ecosystems poses significant barriers to understanding the concepts and technologies behind the Gaia-X framework, which in turn hinders its adoption. In this paper we first elaborate an ecosystem landscape overview, identifying the current state of the key aspects of identity and credential management in dataspaces, with a particular attention to Gaia-X's contributions and role; and then we conduct a systematic literature review of recent academic work addressing identity and credentials in data spaces, paying again special attention to those aligned with the Gaia-X framework. Our analysis shows that most contributions remain at a high conceptual and architectural level, while standards remain fragmented and under continuous development, leading to ongoing interoperability challenges. We conclude that significant progress is still required in the previous areas, but also identify a set of new research direction.