> For the complete documentation index, see [llms.txt](https://docs.teranode.group/tng-identity-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.teranode.group/tng-identity-documentation/tng-identity-verifier/verifier-api/examples/verify-an-email-credential.md).

# Verify an email credential

## Goal

This tutorial walks you through the process of verifying a credential using the Verifier API. The goal is to fetch the Auth Request URI for the selected credential type/template, present it in a user-friendly format (e.g., a QR code), and enable the user to scan it with their Wallet app. While the Wallet app's scanning process is outside the scope of this guide, we will cover everything necessary to prepare for successful verification.

Prerequisite:

* Verifier API Base URL
* Vssuer API Key with a role of Issuer\_Admin
* Credential template ID, also known as the `definitionId` 

## Guide

{% stepper %}
{% step %}

### Getting stared

Prepare your working environment with valid values about the Identity environment you want to work on. 

For reference review the [Getting Started](/tng-identity-documentation/tng-identity-verifier/verifier-api/getting-started.md)
{% endstep %}

{% step %}

### Prepare credential template ID

The only dynamic variable required for the request is the **Credential Template ID**, also referred to as the `definitionId` or `credentialId` (commonly on the Issuer API side). This is typically a **camelCase** string representing the type of credential. For example, in the case of an email credential, the ID is **emailCredential**.

There are two common methods to locate this information:

1. **Retrieve the Credential ID from a Verifiable Credential**:
   * Use the ID of the Issuer's Verifiable Credential to fetch its details via the Issuer API.
   * Call the **"**[Fetch One Credential Offer](broken://pages/eYPRjkL364EpxDobq1j6#private-credential-offers-id)**"** endpoint.
   * In the successful response, locate the `credentialId` field, which represents the Credential Template ID.
2. **Search in the List of Credential Types**:
   * Use the Issuer API to list all credential types and their metadata by calling the appropriate endpoint.
   * Look for your desired credential type in the `credentials_supported` array.
   * The value you need is the `id` field in the corresponding data object.
   * [Read more about this endpoint here](https://docs.teranode.group/tng-identity-documentation/tng-identity-verifier/verifier-api/examples/pages/5AnT5ixOLh7vCBi8LHSd#public-correlationid-.well-known-openid-credential-issuer).
     {% endstep %}

{% step %}

### Fetch verification information

To retrieve the `authRequestURI` for the credential, send a request to the Verifier API using the following steps:

```bash
$API_KEY=INSERT_YOUR_API_KEY_HERE
$IDENTITY_ENV_HASH=426f1ce15bf3df70
$VERIFIER_API_BASE_URL=https://identity.products.teranode.group/products/web/$IDENTITY_ENV_HASH/verifier
curl --location --request POST '$VERIFIER_API_BASE_URL/api/v1/verifiable-presentations/definition/<DEFINITION_ID>' \
--header 'X-API-KEY: $API_KEY'
```

* Replace the placeholder values in `$VERIFIER_API_BASE_URL` and `$API_KEY` with the actual API base URL and a valid access token for your setup.
* For `<DEFINITION_ID>`, use the Credential Template ID you obtained in **Step 2** of this guide.

Upon a successful response, you will receive a data object containing the `authRequestURI` field.  The `correlationId` is used as the record reference id which can be used in subsequent request to the API.

**Important**: The `authRequestURI` is not a standard URL that can be accessed through a browser. It is specifically designed to be readable by compatible Wallet apps for credential verification.

{% hint style="info" %}
View [full API documentation](broken://pages/4JoodhQlHqq1VIGu5cYw#post-private-verifiable-presentations-definition-definitionid) for endpoint used in this section
{% endhint %}

{% endstep %}

{% step %}

### Present the verification URI

Once you have obtained the `authRequestURI`, present it in a format that the user can easily interact with. The most user-friendly option is to generate a **QR code**, which the user can scan with their Wallet app to initiate the verification process.
{% endstep %}

{% step %}

### Monitor the verification status (API Key auth)

After preparing the verification URI, you can track the status of the verification process by polling the **GET /verifiable-presentations/:credentialId** endpoint.

{% code fullWidth="false" %}

```bash
curl --location '$VERIFIER_API_BASE_URL/api/v1/verifiable-presentations/<CORRELATION_ID>' \
--header 'X-API-KEY: $API_KEY' \
--header 'Content-Type: application/json' \
```

{% endcode %}

Along with the previously mentioned `$VERIFIER_API_BASE_URL`, `$API_KEY`,  you’ll need to include the `<CORRELATION_ID>` in the request url. This value is returned from the response in the previous step, look for the `correlationId` value.

When you call the Auth Status endpoint, look for the `status` field in the response to monitor the progress. The status can indicate various stages:

* **created**,
* **scanned**,
* **failed**,
* **valid**,
* **error**

{% hint style="info" %}
View [full API documentation](broken://pages/pHgckwRBAfPjxmJcbsj9#private-webapp-auth-status) for endpoint used in this section
{% endhint %}
{% endstep %}
{% endstepper %}

## Conclusion

By following this tutorial, you can successfully set up and manage the process of verifying a credential using the Verifier API. Fetching the `authRequestURI`, presenting it to users, and integrating Wallet app interactions are key steps in creating a seamless and secure verification workflow. While the Wallet app’s scanning process is beyond the scope of this guide, you now have a comprehensive understanding of how to use the Verifier API to facilitate credential verification.