local_auth_crypto 🔐

Secure data encryption and decryption using biometric authentication for Flutter (Android & iOS).

✨ Features

• 🔒 Biometric Encryption - Encrypt data using biometric authentication
• 🔓 Secure Decryption - Decrypt data only with valid biometric authentication
• 📱 Cross-Platform - Works seamlessly on both Android and iOS
• 🛡️ Hardware Security - Leverages device secure hardware
• 🎯 Simple API - Easy to use encryption/decryption interface
• ⚡ Fast & Efficient - Native implementation for optimal performance

📦 Installation

Add to your pubspec.yaml:

dependencies:
  local_auth_crypto: ^1.1.1

Then run:

flutter pub get

🚀 Quick Start

1. Import the Package

import 'package:local_auth_crypto/local_auth_crypto.dart';

2. Initialize

final localAuthCrypto = LocalAuthCrypto.instance;

3. Encrypt Data

final message = 'SECRET_TOKEN';
final cipherText = await localAuthCrypto.encrypt(message);

4. Decrypt Data

final promptInfo = BiometricPromptInfo(
  title: 'BIOMETRIC',
  subtitle: 'Please scan biometric to decrypt',
  negativeButton: 'CANCEL',
);

final plainText = await localAuthCrypto.authenticate(promptInfo, cipherText);

📱 Platform Setup

🤖 Android Setup

1. Update MainActivity.kt:

import io.flutter.embedding.android.FlutterFragmentActivity

class MainActivity : FlutterFragmentActivity()

2. Add permissions to AndroidManifest.xml:

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

🍎 iOS Setup

Add to your Info.plist:

<dict>
  <key>NSFaceIDUsageDescription</key>
  <string>This application wants to access your TouchID or FaceID</string>
</dict>

📚 API Reference

Encryption Methods

encrypt

Future<CipherText> encrypt(String message)

Encrypts a string message and returns encrypted cipher text.

authenticate

Future<String> authenticate(BiometricPromptInfo promptInfo, CipherText cipherText)

Authenticates user with biometrics and decrypts the cipher text.

BiometricPromptInfo

Configure the biometric prompt:

BiometricPromptInfo({
  required String title,
  required String subtitle,
  required String negativeButton,
  String? description,
  bool confirmationRequired = true,
})

💡 Complete Example

import 'package:local_auth_crypto/local_auth_crypto.dart';

class SecureDataManager {
  final localAuthCrypto = LocalAuthCrypto.instance;
  
  Future<void> saveSecureData(String sensitiveData) async {
    try {
      // Encrypt sensitive data
      final cipherText = await localAuthCrypto.encrypt(sensitiveData);
      
      // Save encrypted data to storage
      await saveToSecureStorage(cipherText);
      
      print('Data encrypted and saved successfully');
    } catch (e) {
      print('Encryption failed: $e');
    }
  }
  
  Future<String?> retrieveSecureData() async {
    try {
      // Retrieve encrypted data from storage
      final cipherText = await getFromSecureStorage();
      
      // Create prompt for biometric authentication
      final promptInfo = BiometricPromptInfo(
        title: 'Authentication Required',
        subtitle: 'Please authenticate to access secure data',
        negativeButton: 'Cancel',
        description: 'Your biometric data is required to decrypt sensitive information',
      );
      
      // Authenticate and decrypt
      final decryptedData = await localAuthCrypto.authenticate(
        promptInfo,
        cipherText,
      );
      
      return decryptedData;
    } catch (e) {
      print('Decryption failed: $e');
      return null;
    }
  }
}

🔍 Error Handling

Handle common scenarios:

try {
  final result = await localAuthCrypto.authenticate(promptInfo, cipherText);
  // Handle successful authentication
} on PlatformException catch (e) {
  switch (e.code) {
    case 'auth_failed':
      print('Authentication failed');
      break;
    case 'auth_canceled':
      print('Authentication canceled by user');
      break;
    case 'not_available':
      print('Biometric authentication not available');
      break;
    case 'not_enrolled':
      print('No biometric data enrolled');
      break;
    default:
      print('Unknown error: ${e.message}');
  }
}

🔒 Security Best Practices

1. Sensitive Data Only: Use this package only for sensitive data that requires biometric protection
2. Error Handling: Always implement proper error handling for authentication failures
3. Fallback Options: Provide alternative authentication methods when biometrics are unavailable
4. Data Validation: Validate decrypted data to ensure integrity
5. Key Management: Never store encryption keys in plain text

📊 Supported Biometric Types

Platform	Supported Biometrics
Android	Fingerprint, Face recognition, Iris
iOS	Touch ID, Face ID

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

💖 Support the Project

If you find this package helpful, please consider supporting it:

🔗 Related Projects

• local_auth_signature
• flutter_biometric_auth
• biometric_storage

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