Digital Product Passports for Circular Supply Chains
5.3 REFERENCE ARCHITECTURE
The reference architecture( Figure 5.1) instantiates the five-layer interoperability stack of Section 4.3 with a federated deployment pattern. Issuers( manufacturers, recyclers, certification bodies) issue Verifiable Credentials against UNTP-aligned schemas, drawing on sector schema sources— Catena-X CX-0143 for batteries, the GBA Battery Passport taxonomy, CIRPASS-2 vocabularies for textiles and electronics, and Trace4Value data points— that sit on the issuer side of the architecture. Those credentials pass through the Cross-border Recognition Bridge, which is composed exclusively of the eIDAS 2.0 trust chain: the QTSP infrastructure that binds each issuer’ s DID to a Qualified Electronic Attestation of Attributes( QEAA), the national trusted lists that anchor QTSP authority per member state, and the Commission’ s List of Trusted Lists that makes recognition automatic across all EU member states [ 28 ]. Holders and verifiers( downstream operators, regulators, customs, consumers) verify credentials against this chain without bilateral negotiation. The mandatory QTSP alignment deadline is September 2026, sitting within the DPP compliance window [ 28 ].
A concrete open source instantiation is available today: the FIWARE Data Space Connector v2, integrating FIWARE Data Space Components with Eclipse Dataspace Components on standard Kubernetes infrastructure [ 22 ]. Its identity and trust layer implements W3C DIDs and Verifiable Credentials with OID4VP and SIOPv2, its authorisation layer enforces ODRL policies, and its contracting layer exposes TM Forum Open APIs— precisely the primitives the interoperability stack of Section 4.3 prescribes.
The Orion LD Context Broker handles exchange, the VCVerifier validates credentials at the trust layer, Keyrock manages authorisation, and a DCAT catalogue supports discovery via the IDS Dataspace Protocol [ 22 ]. Trust is anchored through a Gaia-X Digital Clearing House; sensitive supply data can target Gaia-X Label Level 3, requiring third-party attestation and European control [ 23 ]. At EU level the pattern deploys on Simpl open source middleware, aligning DPP deployment with the wider European data space infrastructure [ 24 ].
The proposed reference architecture is consistent with patterns being validated in the Horizon Europe BASE project, which combines federated data exchange, Digital Battery Passports, and ESG analytics to support EU Battery Regulation requirements.
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