local_auth_kit

On-device authentication for DartNative — Face ID / Touch ID / Optic ID on iOS, and BiometricPrompt (biometrics + optional PIN / pattern / passcode) on Android. Flutter-shaped LocalAuthentication API, pure FFI, no platform channels.

This is an early community plugin. Match the Flutter call sites and swap the import.

Install

dependencies:
  local_auth_kit:
    path: ../dartnative_local_auth   # or the dartpub.dev version once published

dn pub get

void main() {
  DartNativePluginRegistrant.registerAll();
  runApp(const MyApp());
}

The generated registrant calls LocalAuthFFIBindings.loadSymbols().

Usage

import 'package:local_auth_kit/local_auth_kit.dart';

final auth = LocalAuthentication();

if (!await auth.isDeviceSupported()) {
  // no biometrics and no device credential
}

if (await auth.canCheckBiometrics) {
  final kinds = await auth.getAvailableBiometrics();
  // BiometricType.face / fingerprint / iris / weak / strong
}

try {
  final ok = await auth.authenticate(
    localizedReason: 'Unlock to continue',
    biometricOnly: true, // no PIN / passcode fallback
    authMessages: const [
      AndroidAuthMessages(
        signInTitle: 'Unlock to continue',
        cancelButton: 'No thanks',
      ),
      IOSAuthMessages(
        cancelButton: 'No thanks',
        localizedFallbackTitle: 'Use passcode',
      ),
    ],
  );
  if (ok) { /* unlocked */ }
} on LocalAuthException catch (e) {
  if (e.code == LocalAuthExceptionCode.userCanceled) {
    // user backed out
  }
}

local_auth 2.x AuthenticationOptions still works — when passed, its fields override the flattened flags:

await auth.authenticate(
  localizedReason: 'Unlock to continue',
  options: const AuthenticationOptions(
    biometricOnly: true,
    persistAcrossBackgrounding: true,
  ),
);

LocalAuthExceptionCodes aliases the 2.x names onto the 3.x enum, so e.code == LocalAuthExceptionCodes.userCanceled still compiles.

Platform setup

iOS

Add a Face ID usage description to ios/Runner/Info.plist. iOS rejects the prompt without it:

<key>NSFaceIDUsageDescription</key>
<string>Authenticate to unlock the app</string>

No extra entitlements. Touch ID / Optic ID use the same APIs.

Android

The plugin declares USE_BIOMETRIC / USE_FINGERPRINT. The host MainActivity must be a FragmentActivity — DartNative's DartNativeActivity already is (AppCompatActivity).

API

Method	Meaning
`isDeviceSupported()`	Hardware biometrics or a device PIN / pattern / passcode
`canCheckBiometrics`	Biometric hardware is present (enrolled or not)
`getAvailableBiometrics()`	Enrolled / advertised kinds
`authenticate(...)`	Show the system prompt; `true` on success
`stopAuthentication()`	Dismiss an in-flight prompt

authenticate accepts authMessages (AndroidAuthMessages, IOSAuthMessages) to customize title, subtitle, cancel, and iOS fallback copy — the same shape as Flutter local_auth 3.x.

Failures throw LocalAuthException with LocalAuthExceptionCode values: userCanceled, systemCanceled, noBiometricHardware, noBiometricsEnrolled, noCredentialsSet, temporaryLockout, biometricLockout, timeout, uiUnavailable, authInProgress, userRequestedFallback, biometricHardwareTemporarilyUnavailable, deviceError, unknownError.

Platforms

v0.2.0 ships iOS and Android. Other platforms can follow the same FFI surface later.

License

MIT