# NFC Tag

A near-field communication (NFC) tag functions for reauthentication purposes as proof of possession of a piece of hardware (an ID badge or other object with an NFC sticker on it) that is digitally recognizable by the mobile device.<br>

{% embed url="<https://www.youtube.com/watch?t=10s&v=Ng_vnSgM-XE>" %}

If a device has been configured to use NFC for secondary authentication, after logging into the Authentication module, the user will be prompted to tap an NFC tag with their device to associate the tag with the login session.

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

After tapping, the NFC icon will turn green and the user will be allowed to access their logged-in state applications.

When waking a locked device screen, the Auth module will prompt the user to tap the same NFC tag in order to unlock.

If the user taps a different NFC tag that is not associated with the session, the Auth module will display a message stating, "NFC badge data cannot be verified with this session." The NFC icon will turn red, and the user will not be returned to their logged-in state.

If the user taps the NFC tag that they associated with the session, the NFC icon will turn green and the user will be returned to their logged-in state.

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

#### Configuration <a href="#configuration_2" id="configuration_2"></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 `"nfc"` (available in Auth module version 3.2.2+). |

<br>


---

# 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/nfc-tag.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.