  As IoT becomes omnipresent vast amounts of data are generated, which can be
used for building innovative applications. However,interoperability issues and
security concerns, prevent harvesting the full potentials of these data. In
this paper we consider the use case of data generated by smart buildings.
Buildings are becoming ever "smarter" by integrating IoT devices that improve
comfort through sensing and automation. However, these devices and their data
are usually siloed in specific applications or manufacturers, even though they
can be valuable for various interested stakeholders who provide different types
of "over the top" services, e.g., energy management. Most data sharing
techniques follow an "all or nothing" approach, creating significant security
and privacy threats, when even partially revealed, privacy-preserving, data
subsets can fuel innovative applications. With these in mind we develop a
platform that enables controlled, privacy-preserving sharing of data items. Our
system innovates in two directions: Firstly, it provides a framework for
allowing discovery and selective disclosure of IoT data without violating their
integrity. Secondly, it provides a user-friendly, intuitive mechanisms allowing
efficient, fine-grained access control over the shared data. Our solution
leverages recent advances in the areas of Self-Sovereign Identities, Verifiable
Credentials, and Zero-Knowledge Proofs, and it integrates them in a platform
that combines the industry-standard authorization framework OAuth 2.0 and the
Web of Things specifications.
