Identity: did:prism and Verifiable Credentials¶

did:prism¶

The did:prism method is Cardano's W3C-registered DID method. Identity operations (Create, Update, Deactivate) are encoded as Protocol Buffer messages, signed, batched, and published as metadata in Cardano transactions under label 21325.

Property	Value
W3C registered	Yes (March 2023) — W3C DID Registry
Metadata label	21325
Finality depth	112 block confirmations (~37 minutes)
Long-form DIDs	Supported (usable before on-chain anchoring)
DID Document timestamps	From Cardano block metadata

Advantages over did:web¶

	did:web	did:prism
Trust root	DNS (centralized)	Cardano blockchain (decentralized)
Tamper evidence	None (DNS can be hijacked)	On-chain anchoring
Availability	Depends on web server	Immutable once confirmed
Resolution	HTTP GET	Cardano node query
UNTP compliance	Required (minimum)	Supplementary

Hyperledger Identus¶

Formerly Atala PRISM. IOG contributed it to Hyperledger Labs as "Open Enterprise Agent" in October 2023; the community renamed it Hyperledger Identus and it was promoted to Hyperledger Project (Incubation) in April 2024 (announcement).

Implements:

W3C DID Core (did:prism)
W3C VC-JWT (Verifiable Credentials with JWT proof)
Hyperledger AnonCreds (zero-knowledge credential proofs)
DIDComm V2 (peer-to-peer encrypted messaging)

Open source: github.com/hyperledger-identus

NeoPRISM: A Rust reimplementation of the PRISM node/VDR indexer, under active development.

Integration with UNTP DPP¶

The UNTP mandates did:web as the minimum DID method for organizational identifiers. A bridge pattern supports both:

graph TD
    A[Organization] -->|maintains| B["did:web (UNTP compliance)"]
    A -->|publishes| C["did:prism (Cardano anchoring)"]
    B -->|resolves via| D[HTTP / DNS]
    C -->|resolves via| E[Cardano Node]

    F[DPP Verifiable Credential] -->|issuer| B
    F -->|also linked to| C

    G[UNTP Verifier] -->|resolves| B
    H[Cardano Verifier] -->|resolves| C
    H -->|checks| E

A did:prism driver for the Universal Resolver was funded through Catalyst (Fund 8 and Fund 10), though integration into the main resolver repository has not been confirmed as of March 2026.

DPP as Verifiable Credential¶

A Cardano-anchored DPP follows this flow:

Manufacturer creates a DPP as a UNTP-conformant W3C VC in JSON-LD
VC is signed using the manufacturer's did:prism key
Hash of the VC is anchored on Cardano via CIP-68 reference NFT
Full VC stored on IPFS
did:prism DID Document references the manufacturer's identity
Verifier resolves the DID, fetches the VC, checks the signature, and verifies the on-chain hash