Standards
DIDs and verifiable credentials for the digital product passport
W3C Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs) provide the trust layer for high-value DPP records. They are mandatory in Catena-X and recommended for EV batteries, aircraft parts and industrial goods.
DIDs in one paragraph
A DID is a URI that resolves to a DID Document containing public keys and service endpoints. The subject controls the keys, not a registry. Multiple DID methods exist (did:web, did:key, did:ebsi, …); did:web is the pragmatic default, the DID Document is hosted on your domain at a well-known path.
Verifiable Credentials in one paragraph
A VC is a signed assertion by an issuer about a subject: e.g., "Smelter S asserts that ingot I has embodied carbon X." The subject need not trust the issuer's infrastructure, only the issuer's key. Data in the DPP can be composed of many VCs from different tiers of the supply chain.
Choosing a DID method
| Method | When to use |
|---|---|
did:web | You control a stable domain and want low-ceremony adoption. |
did:ebsi | You are in the EBSI ecosystem (European Blockchain Services Infrastructure). |
did:key | Short-lived identifiers, ephemeral attestations. |
Practical advice
- Start with
did:web. Migrate only if a sector requires a ledger-anchored method. - Use JWT-based VCs, the tooling ecosystem is larger than JSON-LD proofs today.
- Rotate keys annually. Publish the revocation list.
- Keep a fallback identifier (GTIN or SGTIN) for retail scanning compatibility.