Indentifiers

When expressing statements about a specific thing, such as a person, product, or organization, it is often useful to use some kind of identifier so that others can express statements about the same thing. This specification defines the optional id property for such identifiers. The id property is intended to unambiguously refer to an object, such as a person, product, or organization. Using the id property allows for the expression of statements about specific things in the verifiable credential.

If the id property is present:

• The id property MUST express an identifier that others are expected to use when expressing statements about a specific thing identified by that identifier.
• The id property MUST NOT have more than one value.
• The value of the id property MUST be a URI.

NOTE: Developers should remember that identifiers might be harmful in scenarios where pseudonymity is required. Developers show understand Identifier-Based Correlation carefully when considering such scenarios. Privacy Considerations that create privacy concerns. Where privacy is a strong consideration, the id property MAY be omitted.

id

The value of the id property MUST be a single URI. It is RECOMMENDED that the URI in the id be one which, if dereferenced, results in a document containing machine-readable information about the id.

Example: Use of id property

examples 1: Credential 
----
{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://www.w3.org/2018/credentials/examples/v1"
  ],
  "id": "http://example.edu/credentials/3732",
  "type": ["VerifiableCredential", "UniversityDegreeCredential"],
  "issuer": "https://example.edu/issuers/565049",
  "issuanceDate": "2010-01-01T00:00:00Z",
  "credentialSubject": {
    "id": "did:example:ebfeb1f712ebc6f1c276e12ec21",
    "degree": {
      "type": "BachelorDegree",
      "name": "Bachelor of Science and Arts"
    }
  }
}

example 2: VCs(with proof)
{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://www.w3.org/2018/credentials/examples/v1",
    "https://w3id.org/security/suites/ed25519-2020/v1"
  ],
  "id": "http://example.edu/credentials/3732",
  "type": [
    "VerifiableCredential",
    "UniversityDegreeCredential"
  ],
  "issuer": "https://example.edu/issuers/565049",
  "issuanceDate": "2010-01-01T00:00:00Z",
  "credentialSubject": {
    "id": "did:example:ebfeb1f712ebc6f1c276e12ec21",
    "degree": {
      "type": "BachelorDegree",
      "name": "Bachelor of Science and Arts"
    }
  },
  "proof": {
    "type": "Ed25519Signature2020",
    "created": "2022-02-25T14:58:42Z",
    "verificationMethod": "https://example.edu/issuers/565049#key-1",
    "proofPurpose": "assertionMethod",
    "proofValue": "z3FXQjecWufY46yg5abdVZsXqLhxhueuSoZgNSARiKBk9czhSePTFehP
8c3PGfb6a22gkfUKods5D2UAUL5n2Brbx"
  }
}

example 3: VCs(as JWT)
---------------- JWT header ---------------
{
  "alg": "ES256",
  "typ": "JWT"
}
--------------- JWT payload ---------------
// NOTE: The example below uses a valid VC-JWT serialization
//       that duplicates the iss, nbf, jti, and sub fields in the
//       Verifiable Credential (vc) field.
{
  "vc": {
    "@context": [
      "https://www.w3.org/2018/credentials/v1",
      "https://www.w3.org/2018/credentials/examples/v1"
    ],
    "id": "http://example.edu/credentials/3732",
    "type": [
      "VerifiableCredential",
      "UniversityDegreeCredential"
    ],
    "issuer": "https://example.edu/issuers/565049",
    "issuanceDate": "2010-01-01T00:00:00Z",
    "credentialSubject": {
      "id": "did:example:ebfeb1f712ebc6f1c276e12ec21",
      "degree": {
        "type": "BachelorDegree",
        "name": "Bachelor of Science and Arts"
      }
    }
  },
  "iss": "https://example.edu/issuers/565049",
  "nbf": 1262304000,
  "jti": "http://example.edu/credentials/3732",
  "sub": "did:example:ebfeb1f712ebc6f1c276e12ec21"
}
--------------- JWT ---------------
eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJ2YyI6eyJAY29udGV4dCI6WyJodHRwczovL3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.giMDNtWUgKbvWL4pteSpSkrh-lhgkhJUZ_gatHdRvEFs9_kB4G9neABvTuuQKfwERzi2KF
Qz3X0nzF-jrOO-5w

The example above uses two types of identifiers. The first identifier is for the verifiable credential and uses an HTTP-based URL. The second identifier is for the subject of the verifiable credential (the thing the claims are about) and uses a decentralized identifier, also known as a DID.

NOTE: As of this publication, DIDs are a new type of identifier that are not necessary for verifiable credentials to be useful. Specifically, verifiable credentials do not depend on DIDs and DIDs do not depend on verifiable credentials. However, it is expected that many verifiable credentials will use DIDs and that software libraries implementing this specification will probably need to resolve DIDs. DID-based URLs are used for expressing identifiers associated with subjects, issuers, holders, credential status lists, cryptographic keys, and other machine-readable information associated with a verifiable credential.