# Credential Revocation Registry

Storing Verifiable Credential on a distributed ledger could lead to privacy violation. However, we can store the status of a Verifiable Credential on-chain, with no private information attached to it. Issuers of a Verifiable Credential have the ability to revoke the credential and provide the reason behind it.

## Syntax of Verifiable Credential (VC) ID

The syntax for Verifiable Credential ID is as follows:

```
vc:hid:<chain-namespace>:<method-specific-id>
```

* `vc:hid` - VC Method, where `vc` is the document identifier and `hid` is the method name
* `<chain-namespace>` - *(Optional)* Name of the blockchain where the VC status is registered. It is omitted for the document registered on mainnet chain
* `<method-specific-id>` - Alpha-numeric string of minimum 32 character length

## VC Status Operations

* **Transaction Based**
  * Register/Update a VC Status Document
* **Query Based**
  * Query a VC Status Document
  * Query Registered VC Status Documents

## Supported VC Statuses

Following are the VC statuses supported by `hid-node`:

* **Live**
* **Suspended**
* **Revoked**
* **Expired**

**NOTE**: VC Statuses are **case sensetive**. `Live` is valid, while `live` is invalid

### Status Change Rules

* Unregistered VC Status Document should only have the status as `Live`
* `Suspended` status can be changed to `Revoked` and `Live`
* `Revoked` and `Expired` statuses cannot be changed

## Supported Hash Algorithm

Following are the supported hash algorithms for the attribute `credentialHash`:

* **SHA-256**

## Register/Update VC Status

Both registeration and update of VC Status happens through the RPC `RegisterCredentialStatus`.

**CLI Signature**

```
Usage:
  hid-noded tx ssi register-credential-status [credential-status] [proof]

Params:
 - credential-status : Credential Status Document
 - proof : Issuer's Signature Format
```

**`credential-status` Structure**

```json
{
    "claim": {
        "id": "vc:hid:<chain-namespace>:z8BXg2zjwBRTrjPs7uCnkFBKrL9bPD14HxEJMENxm3CJ4",
        "currentStatus": "Live",
        "statusReason": "Credential Active"
    },
    "issuer": "did:hid:devnet:zEYJrMxWigf9boyeJMTRN4Ern8DJMoCXaLK77pzQmxVjf",
    "issuanceDate": "2022-04-10T04:07:12Z",
    "expirationDate": "2023-02-22T13:45:55Z",
    "credentialHash": "< -- SHA-256 Hash of VC -->"
}
```

**`proof` Structure**

```json
{
    "type": "Ed25519VerificationKey2020",
    "created": "2022-04-10T04:07:12Z",
    "updated": "2022-04-10T04:07:12Z",
    "verificationMethod": "did:hid:devnet:zEYJrMxWigf9boyeJMTRN4Ern8DJMoCXaLK77pzQmxVjf#key-1",
    "proofValue": "<-- Base64 encoded signature -->",
    "proofPurpose": "assertion"
}
```

The field `proofValue` holds the signature that was produced by signing the `credential-status` document.

**Example**

```
hid-noded tx ssi register-credential-status '{"claim":{"id":"vc:hid:<chain-namespace>:z8BXg2zjwBRTrjPs7uCnkFBKrL9bPD14HxEJMENxm3CJ4","currentStatus":"Live","statusReason":"Credential Active"},"issuer":"did:hid:devnet:zEYJrMxWigf9boyeJMTRN4Ern8DJMoCXaLK77pzQmxVjf","issuanceDate":"2022-04-10T04:07:12Z","expirationDate":"2023-02-22T13:45:55Z","credentialHash":"< -- SHA-256 Hash of VC -->"}' '{"type":"Ed25519VerificationKey2020","created":"2022-04-10T04:07:12Z","updated":"2022-04-10T04:07:12Z","verificationMethod":"did:hid:devnet:zEYJrMxWigf9boyeJMTRN4Ern8DJMoCXaLK77pzQmxVjf#key-1","proofValue":"<-- Base64 encoded signature -->","proofPurpose":"assertion"}' --from <hid-account>
```

## Query VC Status

**CLI Signature**

```
Usage:
  hid-noded q ssi credential-status [credential-id]
```

**Example**

```
hid-noded q ssi credential-status vc:hid:<chain-namespace>:z8BXg2zjwBRTrjPs7uCnkFBKrL9bPD14HxEJMENxm3CJ4
```

**REST**

1. Query credential status for an inpug credential id:

```
http://<REST-URL>/hypersign-protocol/hidnode/ssi/credential/{credId}
```

1. Query list of registered credential statuses:

```
http://<REST-URL>/hypersign-protocol/hidnode/ssi/credential
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.hypersign.id/core-concepts/verifiable-credential-vc/credential-revocation-registry.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.