Poster: Bridging Trust Gaps: Data Usage Transparency in Federated Data Ecosystems.

The evolving landscape of data ecosystems (DEs) increasingly demands integrated and collaborative data-sharing mechanisms that simultaneously ensure data sovereignty. However, recently proposed federated platforms, e.g., Gaia-X, only offer a promising solution to share data among already trusted participants-they still lack features to establish and maintain trust. To address this issue, we propose transparency logs for data usage that retrospectively build trust among participants. Inspired by certificate transparency logs that successfully bridge trust gaps in PKIs, we equip data owners with credible evidence of data usage. We show that our transparency logs for data usage are well scalable to sizable DEs. Thus, they are a promising approach to bridge trust gaps in federated DEs with cryptographic guarantees, fostering more robust data sharing.