LocalAuthentication

expo-local-authentication allows you to use FaceID and TouchID (iOS) or the Biometric Prompt (Android) to authenticate the user with a face or fingerprint scan.

Platform Compatibility

Android Device	Android Emulator	iOS Device	iOS Simulator	Web
				Pending

Installation

expo install expo-local-authentication

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

Configuration

On Android, this module requires permissions to access the biometric data for authentication purposes. The USE_BIOMETRIC and USE_FINGERPRINT permissions are automatically added.

API

import * as LocalAuthentication from 'expo-local-authentication';

Methods

`LocalAuthentication.hasHardwareAsync()`

Determine whether a face or fingerprint scanner is available on the device.

Returns

Returns a promise resolving to boolean value indicating whether a face or fingerprint scanner is available on this device.

`LocalAuthentication.supportedAuthenticationTypesAsync()`

Determine what kinds of authentications are available on the device.

Returns a promise resolving to an array containing LocalAuthentication.AuthenticationType.{FINGERPRINT, FACIAL_RECOGNITION, IRIS}. A value of 1 indicates fingerprint support, 2 indicates facial recognition support, and 3 indicates iris recognition support (Android-only). Devices can support multiple authentication methods- i.e. [1,2] means the device supports both fingerprint and facial recognition. If none are supported, this method returns an empty array.

`LocalAuthentication.isEnrolledAsync()`

Determine whether the device has saved fingerprints or facial data to use for authentication.

Returns

Returns a promise resolving to boolean value indicating whether the device has saved fingerprints or facial data for authentication.

`LocalAuthentication.authenticateAsync(options)`

Attempts to authenticate via Fingerprint/TouchID (or FaceID if available on the device).

Note: Apple requires apps which use FaceID to provide a description of why they use this API. If you try to use FaceID on an iPhone with FaceID without providing infoPlist.NSFaceIDUsageDescription in app.json, the module will authenticate using device passcode. For more information about usage descriptions on iOS, see Deploying to App Stores.

Arguments

options (object) -- An object of options.
- promptMessage (string) -- A message that is shown alongside the TouchID or FaceID prompt.
- cancelLabel (string) -- Allows to customize the default Cancel label shown.
- fallbackLabel (string) -- Allows to customize the default Use Passcode label shown after several failed authentication attempts. Setting this option to an empty string disables this button from showing in the prompt. (iOS only)
- disableDeviceFallback (boolean) -- After several failed attempts the system will fallback to the device passcode. This setting allows you to disable this option and instead handle the fallback yourself. This can be preferable in certain custom authentication workflows. This behaviour maps to using the iOS LAPolicyDeviceOwnerAuthenticationWithBiometrics policy rather than the LAPolicyDeviceOwnerAuthentication policy. Defaults to false.

Returns

Returns a promise resolving to an object containing success, a boolean indicating whether or not the authentication was successful, and error containing the error code in the case where authentication fails.

`LocalAuthentication.cancelAuthenticate()`

(Android Only) Cancels authentication flow.