> For the complete documentation index, see [llms.txt](https://docs.bluefletch.com/bluefletch-enterprise/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.bluefletch.com/bluefletch-enterprise/product-guides/authentication-and-sso/features/secondary-authentication/barcode.md).

# 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"`. |


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