How to Implement Biometric Authentication in Flutter

Introduction:

Biometric authentication has become increasingly popular as a secure and convenient method for user authentication in mobile applications. Flutter, Google's UI toolkit for building beautiful and native applications, provides developers with a robust framework to integrate biometric authentication seamlessly. In this blog post, we will explore how to handle biometric authentication in Flutter and provide a step-by-step guide with examples.

Prerequisites:

To follow along with this tutorial, you should have a basic understanding of Flutter development and have Flutter and Dart installed on your machine.

Step 1: Add Dependencies

First, open your project in Flutter and navigate to the pubspec.yaml file. Add the following dependencies:

dependencies:
  local_auth: ^2.0.1

Save the file and run flutter pub get to fetch the required packages.

Step 2: Import Packages

In your Dart file, import the necessary packages:

import 'package:flutter/material.dart';
import 'package:local_auth/local_auth.dart';

Step 3: Check Device Support

Before implementing biometric authentication, you should verify if the device supports it. You can do this by using the LocalAuthentication class and the canCheckBiometrics method. Add the following code inside your widget's build method:

LocalAuthentication localAuth = LocalAuthentication();
bool isBiometricSupported = false;


Future<void> checkBiometricSupport() async {
  try {
    isBiometricSupported = await localAuth.canCheckBiometrics;
  } catch (e) {
    print(e);
  }
}


@override
void initState() {
  super.initState();
  checkBiometricSupport();
}

Step 4: Authenticate Using Biometrics

To authenticate using biometrics, you can use the authenticate method from the LocalAuthentication class. Add the following code to your widget's build method:

Future<void> authenticate() async {
  try {
    bool isAuthenticated = await localAuth.authenticate(
      localizedReason: 'Please authenticate to access the app',
      useErrorDialogs: true,
      stickyAuth: true,
    );


    if (isAuthenticated) {
      // Biometric authentication successful, proceed with app access.
    } else {
      // Biometric authentication failed.
    }
  } catch (e) {
    print(e);
  }
}

Step 5: UI Integration

Now, it's time to integrate the biometric authentication functionality with your app's UI. You can use buttons or any other widgets to trigger the authentication process. For example:

RaisedButton(
  onPressed: () {
    if (isBiometricSupported) {
      authenticate();
    } else {
      // Biometric authentication not supported on this device.
    }
  },
  child: Text('Authenticate with Biometrics'),
)

Step 6: Test Your Implementation

Finally, you can run your Flutter application on a device or emulator to test the biometric authentication. When you tap the "Authenticate with Biometrics" button, it will trigger the authentication process. If the device supports biometrics and the user successfully authenticates, you can implement the necessary logic for granting access to your app.

Conclusion:

Integrating biometric authentication into your Flutter app can enhance security and improve user experience. In this blog post, we explored how to handle biometric authentication in Flutter, from checking device support to implementing the authentication process. By following these steps, you can easily incorporate biometric authentication into your Flutter applications and provide your users with a secure and convenient login experience.

Remember to handle any potential errors or exceptions that may occur during the authentication process to ensure a smooth user experience. With Flutter's versatility and the local_auth package, you can create powerful applications that leverage the benefits of biometric authentication.