> For the complete documentation index, see [llms.txt](https://docs.verifone.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.verifone.com/api-reference/open-api-references/3d-secure/jwt.md).

# JWT

The **JWT endpoints** handle the authentication handshake between your server and the 3DS Client SDK. JWT Create produces a signed token the SDK uses to initialise the 3DS session; JWT Validate decodes the token returned by the SDK after cardholder authentication and provides the final authentication outcome.

{% stepper %}
{% step %}

### Step 1 — Create a JWT

The JWT Create endpoint produces a signed JSON Web Token used as the initial authentication handshake with the 3DS Client SDK. Pass this token to the SDK on page load before initiating the Lookup flow.

{% hint style="info" %}
The `jwt` value returned by this endpoint should be passed to `Cardinal.setup()` (or the equivalent SDK initialisation call) as the session token. The `device_info_id` returned here should be included in the subsequent [Lookup](/api-reference/open-api-references/3d-secure/lookup.md) request.
{% endhint %}
{% endstep %}

{% step %}

### Step 2 — Validate a JWT

After the cardholder completes the 3DS authentication (frictionless or challenge), the 3DS Client SDK returns a signed JWT. Pass this JWT to the Validate endpoint to decode the result and retrieve the authentication outcome.

{% hint style="danger" %}
The `authentication_id` in the JWT Validate response must match the `authentication_id` from your original [Lookup](/api-reference/open-api-references/3d-secure/lookup.md) response. Store the Lookup `authentication_id` before calling Validate and verify the values match before proceeding to authorization.
{% endhint %}
{% endstep %}
{% endstepper %}

## JWT Validate Response Fields

```
JwtValidateResponse
  ├── authentication_id   ← Match against Lookup response — required for authorization
  ├── action_code         ← Resulting state of the transaction
  ├── error_no            ← 0 = no error; non-zero = error encountered
  ├── error_desc          ← Human-readable error description (comma-separated if multiple)
  └── validation_result   ← Full authentication result object
```

{% hint style="warning" %}
A non-zero `error_no` indicates an error during JWT processing. Multiple errors are returned as comma-separated values in `error_no` and `error_desc`. Do not proceed to authorization if `error_no` is non-zero.
{% endhint %}

## Full Flow Summary

{% columns %}
{% column %}

#### JWT Create (Step 1)

1. Call `POST /v2/jwt/create` from your server
2. Pass the returned `jwt` to the 3DS Client SDK
3. Store the `device_info_id` for the Lookup request
4. SDK initialises the 3DS session
   {% endcolumn %}

{% column %}

#### JWT Validate (Step 2)

1. SDK returns a JWT after cardholder authentication
2. Call `POST /v2/jwt/validate` with that JWT
3. Verify `authentication_id` matches Lookup
4. Use `action_code` and `validation_result` to complete authorization
   {% endcolumn %}
   {% endcolumns %}


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