# Issuing a Verifiable Credential referencing Status List

### Issuing a Verifiable Credential referencing cheqd StatusList

Follow the [instructions for issuing a Verifiable Credential here](https://docs.cheqd.io/product/sdk/veramo/credentials), including the `credentialStatus` information, as shown in the example below:

```json
{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://veramo.io/contexts/profile/v1"
  ],
  "issuer": {
    "id": "did:cheqd:testnet:zGgLTsq96mTsFcFBUCxX6k4kc5i5RNpY"
  },
  "type": [
    "VerifiableCredential",
    "Profile"
  ],
  "issuanceDate": "2022-07-28T15:25:10.000Z",
  "credentialSubject": {
    "name": "Alice",
    "id": "did:key:z6Mkktr27VZ7TTFoTsD9p79JwtGnQDgJWKGrxJ79quE7M5Yx"
  },
  "credentialStatus": {
    "id": "https://resolver.cheqd.net/1.0/identifiers/did:cheqd:testnet:9c01bc05-178b-4742-a189-9b56933df971?resourceName=unencrypted-test-list&resourceType=BitstringStatusListCredential#65675",
    "type": "BitstringStatusListEntry",
    "statusPurpose": "message",
    "statusListIndex": "65675",
    "statusListCredential": "https://resolver.cheqd.net/1.0/identifiers/did:cheqd:testnet:9c01bc05-178b-4742-a189-9b56933df971?resourceName=unencrypted-test-list&resourceType=BitstringStatusListCredential",
    "statusSize": 2,
    "statusMessage": [
            {
                "status": "0x0",
                "message": "valid"
            },
            {
                "status": "0x1",
                "message": "revoked"
            },
            {
                "status": "0x2",
                "message": "suspended"
            },
            {
                "status": "0x3",
                "message": "unknown"
            }
    ]
  },
  "proof": {
    "type": "JwtProof2020",
    "jwt": "eyJhbGciOiJFZERTQSIsInR5cCI6IkpXVCJ9.eyJ2YyI6eyJAY29udGV4dCI6WyJodHRwczovL3d3dy53My5vcmcvMjAxOC9jcmVkZW50aWFscy92MSIsImh0dHBzOi8vdmVyYW1vLmlvL2NvbnRleHRzL3Byb2ZpbGUvdjByb2ZpbGUvdjEiXSwidHlwZSI6WyJWZXJpZmlhYmxlQ3JlZGVudGlhbCIsIlByb2ZpbGUiXSwiY3JlZGVudGlhbFN1YmplY3QiOnsibmFtZSI6IkFsaWNlIn19LCJzdWIiOiJkaWQ6a2V5Ono2TWtrdHIyN1ZaN1RURm9Uc25RRGdKV0tHc0Q5cDc5Snd0R25RRGdKV0tHcnhKNzlxdUU3TTVZeCIsIm5iZiI6MTY1OTAyMTkxMCwiaXNzIjoiZGlkOmNoZXFkOm1haW5uZXQ6ekFYd3dxWnpoQ1pBMUw3N1pCYThmaFZOakw5TVFDSFgifQ.MRqlKuFQzpjLvsW3C2ZSBEf5jfvJCPQBwl-gP1P8bRfNSvjxj9H3eDgDmEf5jfvJCPQBwUDltBr-ZQ3Q7SKVSvCaJHV8TnUzBA"
  }
}
```

Where the values within the credentialStatus field are as follows:

| Property               | Description                                                                                                                                                                                                                 |
| ---------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `id`                   | A specific DID URL dereferencing to the actual status of the Credential                                                                                                                                                     |
| `type`                 | The `type` property *MUST* be `BitstringStatusListEntry`                                                                                                                                                                    |
| `statusPurpose`        | The purpose of the status entry *MUST* be a string. While the value of the string is arbitrary, the following values *MUST* be used for their intended purpose: **message** or **revocation** or **suspension**             |
| `statusListIndex`      | The `statusListIndex` property *MUST* be an arbitrary size integer greater than or equal to 0, expressed as a string. The value identifies the bit position of the status of the verifiable credential.                     |
| `statusListCredential` | The `statusListCredential` property *MUST* is a DID URL to a statusList Resource. When the URL is dereferenced, the resulting Resource *MUST* have `type` property that includes the `BitstringStatusListCredential` value. |
| `statusSize`           | Size of each bit in Bitstring Status List                                                                                                                                                                                   |
| `statusMessage`        | Array containing 2^statusSize entries which defines the meaning for each bit of the Bitstring Status List                                                                                                                   |

#### Validate Algorithm for cheqd StatusList

The following process, or one generating the exact output, *MUST* be followed when validating a verifiable credential that is contained in a cheqd StatusList Resource.

1. Let **credentialToValidate** be a verifiable credentials containing a `credentialStatus` entry that is a BitstringStatusListEntry, associated with an entry in a bitstring.
2. Let **status purpose** be the value of `statusPurpose` in the `credentialStatus` entry in the **credentialToValidate**.
3. Verify all proofs associated with the **credentialToValidate**. If a proof fails, return a validation error.
4. Verify that the **status purpose** matches the `resourceType` value in the **BitstringStatusList Resource**.
5. Let **compressed bitstring** be the value of the `encodedList` property of the **BitstringStatusList Resource**.
6. Let **credentialIndex** be the value of the `statusListIndex` property of the bitstring in the **BitstringStatusList Resource**.
7. Generate a **revocation/suspension/other bitstring** by passing **compressed bitstring** to the [Bitstring Expansion Algorithm](https://w3c-ccg.github.io/vc-status-list-2021/#bitstring-expansion-algorithm).
8. Let **status** be the value of the bit at position **credentialIndex** in the **revocation bitstring**.
9. Return `true` if **status** is 1, `false` otherwise.