# Barcode

For a device configured to reauthenticate by barcode, the user will be prompted to scan a barcode after logging into the Auth module. Scanning the barcode will associate it with the session.

When the user locks the device screen and wakes it again, they can scan the same barcode to successfully verify their identity and access their applications in the logged-in state. If a different barcode is scanned, the barcode icon will turn red, and the user will receive an error message that that session cannot be verfied by the barcode data and will be able to try again.

<img src="https://emsdocs.bluefletch.com/assets/img/auth/barcodeBadScan.png" alt="" width="300">

#### Configuration <a href="#configuration_3" id="configuration_3"></a>

The following key-value pair can be set within the [`settings`](/bluefletch-enterprise/product-guides/bluefletch-launcher/launcher3/technical-guide.md#settings) object of the Launcher configuration JSON file.

**Settings for NFC:**

| Field            | Data Type | Description                                            |
| ---------------- | --------- | ------------------------------------------------------ |
| useSecondaryAuth | string    | (See description above.) Assign the value `"barcode"`. |


---

# 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.bluefletch.com/bluefletch-enterprise/product-guides/authentication-and-sso/features/secondary-authentication/barcode.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.