Using Biometric Authentication in Flutter

Biometric authentication is a secure and user-friendly way to verify a user’s identity using unique physical characteristics like fingerprints or facial recognition. In Flutter, you can easily implement biometric authentication using the local_auth package, which supports both Android and iOS.

Why Use Biometric Authentication?

Biometric authentication offers multiple advantages over traditional PINs or passwords:

Step-by-Step Implementation

1. Add Dependencies

To get started, add the following dependency in your pubspec.yaml file:

dependencies:
  local_auth: ^2.1.6

Run flutter pub get to install the package.

2. Configure Android and iOS

On Android, update your AndroidManifest.xml:

<uses-permission android:name="android.permission.USE_BIOMETRIC"/>

Also, make sure your minSdkVersion is set to at least 23.

On iOS, update Info.plist with:

<key>NSFaceIDUsageDescription</key>
<string>This app uses Face ID to authenticate users.</string>

3. Code Sample

Here’s a simple implementation of biometric authentication in Flutter:

import 'package:local_auth/local_auth.dart';

final LocalAuthentication auth = LocalAuthentication();

Future<void> authenticateUser() async {
  final bool canCheckBiometrics = await auth.canCheckBiometrics;
  final bool isAuthenticated = await auth.authenticate(
    localizedReason: 'Scan your fingerprint to authenticate',
    options: const AuthenticationOptions(
      biometricOnly: true,
      stickyAuth: true,
    ),
  );

  if (isAuthenticated) {
    // Proceed with secure action
  } else {
    // Handle failure
  }
}

4. Best Practices

• Always provide an alternative authentication method like PIN.
• Inform users when and why biometrics are required.
• Avoid storing sensitive data without encryption, even after successful authentication.

5. Real-World Use Cases

• Banking and financial apps
• Password manager apps
• E-commerce checkouts
• Access to sensitive user data

Security Concerns and Considerations

While biometric data is more secure than passwords, it still requires attention to detail. Data should never be stored on a server and should rely on the secure elements provided by Android and iOS devices.

For a deeper understanding of Flutter security and authentication, refer to Flutter Security Guidelines.

Conclusion

Implementing biometric authentication in Flutter enhances both security and user experience. With just a few lines of code and proper configuration, your app can provide a seamless and secure login experience. Always remember to keep your app updated and follow the platform’s best security practices.