Verifiable Credential Status on hid-node

[Vishwas1]

so far the way we have verifiable credential which has nothing to do with hid-node or blockchain. The problem here is, once the credential is issued by the issuer, there is no way to revoke the credential unless it expired. We need to implement a define something called credentailStatus on the hid-node. we can take a look at vc-data-model spec in w3c

CredentialStatus

The credentialStatus property is used for the discovery of information about the current status of a verifiable credential, such as whether it is suspended or revoked.

This property MUST include the following fields:

• id
• type: which expresses the credential status type also referred to as the credential status method. Example is CredentialStatusList2017.

One possible format of the id could be:

did:hid:{hid-wallet-address}/credentials/{hash}

To create hash, the JSON document must be serialized according to the JSON-LD specificaion. The ensures that JSON document has same format when validating the credenital. The id, credentialStatus and proof fields should be ommited when creating the hash.

This id can be used to query the blockchain and fetch the credential status of that particular credential

Example of CredentialStatus

{
  ...
  "credentialStatus": {
    "id": "did:hid:3JugjxT51cTjWAsgnQK4SpmMqK6qua1VpXH/credentials/BYQRy1DbXpDKHTM1qmEAdrv3XzgUu5RfmrgSANkUibwY/status",
    "type": "CredentialStatusList2017"
  }
}

Example 2

"credentialStatus": {
    "id": "https://example.edu/status/24",
    "type": "CredentialStatusList2017"
  },

Sample VC with credential status

{
  "@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/14",
  "issuanceDate": "2010-01-01T19:23:24Z",
  "credentialSubject": {
    "id": "did:example:ebfeb1f712ebc6f1c276e12ec21",
    "degree": {
      "type": "BachelorDegree",
      "name": "Bachelor of Science and Arts"
    }
  },
  "credentialStatus": {
    "id": "https://example.edu/status/24",
    "type": "CredentialStatusList2017"
  }
}

But the next question is, what will happen when you query a particual VC id in blockchain? What it is going to return? How will that be implemented? This is where the concept of Verifiable Credential Extension Registry

Ref:

• Credential Status List 2017
• https://www.w3.org/TR/vc-data-model/#status
• https://w3c-ccg.github.io/vc-extension-registry/#status-methods
• https://www.w3.org/TR/vc-data-model/#status