Master theses

Verifiable Credentials (VCs) are rapidly becoming the backbone of digital identity infrastructure — from the EU Digital Identity Wallet (EUDIW) and the European Blockchain Services Infrastructure (EBSI) to national health records and academic diplomas. A VC is a tamper-evident, cryptographically signed digital document: a government proves you are who you say you are, and you present exactly the relevant portion of that proof to a verifier — without revealing anything more. This selective disclosure property is fundamental to privacy.

The dominant VC ecosystem is JSON and JSON-LD-centric, including OpenID for Verifiable Credential Issuance (OID4VCI) and OpenID for Verifiable Presentations (OID4VP), and presentation flows operate at the JSON layer using JSONPath expressions to select which credential fields to disclose. This creates a deep tension with the Semantic Web world. RDF is the native language of interoperable, linked data, and organisations that manage their data as Knowledge Graphs find that the VC ecosystem treats RDF as a second-class citizen: you can serialise your credentials as JSON-LD, but the moment you want to query, reason over, or selectively disclose from them, you are forced back into JSON tooling.

A recent demo paper from IDLab, Towards Queryable Verifiable Credentials (De Mulder et al., ISWC 2025), shows a promising first step: converting VCs to RDF, running SPARQL queries over them, and constructing query-driven Verifiable Presentations. However, the current pipeline still relies on JSON-based VC libraries to create the final Verifiable Presentation, including the reverse transformation from SPARQL-selected RDF data into JSONPath-based disclosure instructions. This dependency is the key future-work challenge: OID4VP itself needs a clean SPARQL-aware extension so query-based disclosure becomes a first-class protocol feature rather than a custom conversion layer.

In this thesis, you will design and prototype an OID4VC/OID4VP extension that adds native SPARQL support for requesting and delivering Verifiable Presentations. You will build on the queryable VC architecture from the IDLab demo paper and focus on protocol design, interoperability, and implementation strategy for SPARQL-driven selective disclosure.

Concretely, you will study the OID4VP protocol and identify where JSON assumptions are baked in, then design an extension profile that allows verifiers to express disclosure requests as SPARQL patterns or query templates instead of JSONPath selectors. You will prototype this as a working flow in which a holder receives a SPARQL-based presentation request, evaluates it against credential data represented as RDF, and returns a standards-compliant Verifiable Presentation.

You will evaluate your system on realistic identity scenarios — think presenting only your age from a national ID, or only your degree title from a diploma — and assess correctness of disclosure, protocol compatibility, and developer ergonomics compared to JSONPath-based approaches. The work sits at the crossroads of Semantic Web standards, protocol engineering, and digital identity infrastructure, all of which are intensely active research and policy areas in Europe right now. You will work directly with the IDLab authors of the ISWC demo paper, giving you immediate access to the existing prototype and a clear path to extending it into a publishable research contribution.

The thesis targets a scoped protocol extension profile with an interoperable proof-of-concept, not a complete replacement of existing OID4VC ecosystems.