Implementing Security Best Practices

import 'dart:io';
import 'dart:convert';

Future<dynamic> fetchUserData(String userId) async {
  final client = HttpClient();
  client.connectionTimeout = const Duration(seconds: 10);
  final request = await client.getUrl(Uri.parse("https://api.example.com/users/$userId"));
  final response = await request.close();
  final data = await response.transform(utf8.decoder).join();
  return jsonDecode(data);
}

import 'package:flutter_secure_http/flutter_secure_http.dart';

final client = SecureHttpClient();
client.addPinnedCertificate(
  host: 'api.example.com',
  certificateFingerprint: 'sha256/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=',
);

final response = await client.get('https://api.example.com/data');

import 'package:flutter_secure_storage/flutter_secure_storage.dart';

final storage = FlutterSecureStorage();

// Write sensitive data
await storage.write(key: 'api_token', value: 'abc123xyz');

// Read sensitive data
String? token = await storage.read(key: 'api_token');

class LoginForm extends StatefulWidget {
  @override
  _LoginFormState createState() => _LoginFormState();
}

class _LoginFormState extends State<LoginForm> {
  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: [
          TextFormField(
            controller: _emailController,
            decoration: InputDecoration(labelText: 'Email'),
            validator: (value) {
              if (value == null || value.isEmpty) return 'Email is required';
              if (!RegExp(r'^[^@]+@[^@]+\.[^@]+').hasMatch(value)) {
                return 'Invalid email';
              }
              return null;
            },
          ),
          TextFormField(
            controller: _passwordController,
            decoration: InputDecoration(labelText: 'Password'),
            obscureText: true,
            validator: (value) {
              if (value == null || value.isEmpty) return 'Password is required';
              if (value.length < 8) return 'Password must be at least 8 characters';
              return null;
            },
          ),
        ],
      ),
    );
  }
}

// Initialize Firebase
await Firebase.initializeApp();

// Sign in with email and password
final user = await FirebaseAuth.instance
    .signInWithEmailAndPassword(email: 'user@example.com', password: 'password123');

// Get user info
final uid = user.user!.uid;

// Configure OAuth provider (e.g., Google)
final result = await FlutterWebAuth.authenticate(
  url: 'https://accounts.google.com/o/oauth2/v2/auth?client_id=...&redirect_uri=flutter_web_auth_42://',
  callbackUrlScheme: 'flutter_web_auth_42',
);

// Parse the returned token
final token = Uri.parse(result).queryParameters['access_token'];

import 'package:flutter_dotenv/flutter_dotenv.dart';

final String apiUrl = DotEnv().env['API_URL'] ?? 'https://default-api.com';
final String secretKey = DotEnv().env['SECRET_KEY'] ?? 'default-key';
final bool debugMode = DotEnv().env['DEBUG_MODE'] == 'true';

void main() {
  runApp(MyApp(
    apiUrl: apiUrl,
    secretKey: secretKey,
    debugMode: debugMode,
  ));
}

flutter:
  uses-material-design: true
  obfuscation: true

import "package:flutter_secure_storage/flutter_secure_storage.dart";

class ConfigManager {
  static const String API_KEY = "api_key";
  final FlutterSecureStorage _storage = const FlutterSecureStorage();

  Future<String> getApiKey() async {
    final key = await _storage.read(key: API_KEY);
    if (key == null) {
      throw Exception("API key not found");
    }
    return key;
  }

  Future<void> setApiKey(String key) async {
    await _storage.write(key: API_KEY, value: key);
  }
}

import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:local_auth/local_auth.dart';

final LocalAuthentication auth = LocalAuthentication();
bool canCheckBiometrics = await auth.canCheckBiometrics;
List<BiometricType> availableBiometrics = await auth.getAvailableBiometrics();
bool authenticated = await auth.authenticate(
  localizedReason: 'Please authenticate to proceed',
  options: const AuthenticationOptions(
    biometricOnly: true,
    stickyAuth: true,
  ),
);

# Keep your main application classes
-keep class com.yourcompany.yourapp.** { *; }

# Prevent removal of JavaScript interface methods
-keepclassmembers class * { @android.webkit.JavascriptInterface <methods>; }

# Keep all Activity classes
-keep public class * extends android.app.Activity

# Prevent obfuscation of specific libraries
-keep class com.google.gson.** { *; }