NFCGuard - Secure NFC Tag Writer with Unique Code Protection 🔐

A sophisticated Flutter application for securely writing NFC tags with unique codes and Brazilian CPF validation

Features   |    Security   |    Technologies   |    Installation   |    Configuration   |    Usage   |    License

✨ Features

Secure NFC Writing 🔐

• Unique Code Generation - 8-character secure codes for each tag
• Anti-Replication Protection - Prevents code reuse and duplication
• Multiple Tag Support - Write up to 8 different datasets per NFC tag
• Real-Time Validation - Instant verification of code validity
• Secure Storage - Encrypted storage for sensitive data using Flutter Secure Storage
• Usage Tracking - Monitor and prevent duplicate code usage
• 🆕 Enterprise Logging - Complete NFC operation audit trail
• 🆕 Cloud Synchronization - Real-time data backup with Supabase

Brazilian Integration 🇧🇷

• CPF Validation - Built-in Brazilian CPF document validation
• CEP Lookup - Automatic postal code verification and address lookup
• Portuguese Interface - Fully localized in Portuguese
• Brazilian Standards - Compliance with local data protection requirements
• Local Storage - Secure local data persistence with SharedPreferences

Modern Architecture 🏗️

• Riverpod State Management - Reactive state management with code generation
• Material Design 3 - Modern UI components with light/dark theme support
• Clean Architecture - Organized code structure with separation of concerns
• Type Safety - Full Dart null safety implementation
• Code Generation - Automated provider and JSON serialization generation
• 🆕 Supabase Integration - Real-time backend with PostgreSQL database
• 🆕 Cloud Authentication - Secure user management and session handling

🛡️ Security Features

Code Protection System 🔒

# Security Measures:
✅ 8-character unique code generation
✅ Code reuse prevention system
✅ Encrypted secure storage
✅ Usage history tracking
✅ Anti-tampering validation
✅ Secure key management

Data Protection

# Security Implementation:
- Flutter Secure Storage for sensitive data
- Local validation before NFC write
- Code uniqueness verification
- Encrypted user data storage
- Secure token management
- Protected against replay attacks
- 🆕 Cloud data encryption with Supabase
- 🆕 Operation logging and audit trails

NFC Security

# NFC Protection:
- Unique identifiers per tag
- Multiple dataset support (up to 8)
- Secure write protocols
- Tag authentication
- Anti-cloning measures
- 🆕 Enterprise operation logging
- 🆕 Real-time monitoring and alerts

💻 Technologies

Core Framework

• Flutter 3.9.0+ - Cross-platform mobile framework
• Dart 3.0+ - Modern programming language
• Material Design 3 - Contemporary UI components

Backend & Database

• Supabase 2.5.6 - Real-time backend-as-a-service
• PostgreSQL - Robust relational database
• Real-time subscriptions - Live data synchronization
• Authentication - Built-in user management

State Management & Architecture

• Riverpod 2.4.9 - Reactive state management
• riverpod_annotation 2.3.3 - Code generation annotations
• riverpod_generator 2.3.9 - Provider code generation

NFC & Hardware

• nfc_manager 4.0.2 - NFC tag reading and writing
• NFC Operation Logging - Enterprise-level operation tracking
• Native Android/iOS NFC - Platform-specific NFC implementations
• Hardware Security - Secure element integration where available

Brazilian Localization

• all_validations_br 3.0.0 - Brazilian document validation
• search_cep 4.0.2 - Brazilian postal code API integration
• Portuguese Localization - Full app translation and formatting

Data & Storage

• flutter_secure_storage 9.0.0 - Encrypted key-value storage
• shared_preferences 2.2.2 - Local preferences storage
• http 1.1.0 - HTTP client for API calls

Development Tools

• build_runner 2.4.7 - Code generation automation
• json_annotation 4.8.1 - JSON serialization annotations
• json_serializable 6.7.1 - JSON code generation
• flutter_lints 5.0.0 - Dart/Flutter linting rules

📦 Installation

Prerequisites

• Flutter SDK 3.9.0+
• Android Studio or * VS Code*
• Git
• NFC-enabled Device (Android/iOS with NFC support)

Quick Start

1. Clone the repository

git clone https://github.com/gabrielmaialva33/nfc-guard.git
cd nfc-guard

2. Install dependencies

flutter pub get

3. Generate code

flutter packages pub run build_runner build

4. Check Flutter setup

flutter doctor

5. Run on device

# Android device (NFC required)
flutter run

# iOS device (NFC required)
flutter run -d ios

# Check connected devices
flutter devices

6. Build for production

# Android APK
flutter build apk --release

# iOS (requires Xcode and Apple Developer account)
flutter build ios --release

⚙️ Configuration

NFC Permissions

Android

<!-- Required for NFC functionality -->
<uses-permission android:name="android.permission.NFC" /><uses-feature
android:name="android.hardware.nfc" android:required="true" />

    <!-- Optional: for enhanced NFC features -->
<uses-permission android:name="android.permission.NFC_PREFERRED_PAYMENT_INFO" />

iOS

<!-- Info.plist -->
<key>NFCReaderUsageDescription</key><string>This app uses NFC to write secure tags with unique
codes
</string>

    <!-- Required NFC entitlements -->
<key>com.apple.developer.nfc.readersession.formats</key><array>
<string>NDEF</string>
<string>TAG</string>
</array>

Code Generation Setup

1. Watch for Changes (Development):

flutter packages pub run build_runner watch

2. One-time Generation:

flutter packages pub run build_runner build

3. Clean and Rebuild:

flutter packages pub run build_runner clean
flutter packages pub run build_runner build --delete-conflicting-outputs

Environment Configuration

Create necessary configuration files:

// lib/core/config/supabase_config.dart
class SupabaseConfig {
  static const String supabaseUrl = 'YOUR_SUPABASE_URL';
  static const String supabaseAnonKey = 'YOUR_SUPABASE_ANON_KEY';
}

// lib/core/config/app_config.dart
class AppConfig {
  static const String cepApiUrl = 'https://viacep.com.br/ws/';
  static const bool enableDebugMode = false;
  static const bool enableNfcLogging = true;
}

🔌 Usage

Basic Workflow

1. Launch App - Open NFCGuard
2. Authentication - Enter CPF for Brazilian users
3. Generate Code - Create unique 8-character security code
4. Prepare NFC Tag - Hold NFC tag ready
5. Write Tag - Tap "Write to NFC" and hold tag to device
6. Verification - Confirm successful write and code storage

NFC Tag Writing Process

# Step-by-step Process:
1. 📱 Open NFCGuard app
2. 🆔 Validate Brazilian CPF
3. 🔐 Generate unique security code
4. 📡 Enable NFC on device
5. 🏷️ Place NFC tag near device
6. ✍️ Write data to tag
7. ✅ Verify successful write
8. 💾 Store usage history

Code Management

Code Generation:

• Automatically generates 8-character codes
• Validates uniqueness against stored history
• Prevents code replication and reuse
• Encrypts codes in secure storage

Code Validation:

• Real-time validation during generation
• Checks against previously used codes
• Validates format and structure
• Provides instant feedback

Usage Tracking:

• Records all generated codes
• Tracks write timestamps
• Prevents duplicate usage
• Maintains audit trail

Supported NFC Tags

# Compatible NFC Tag Types:
✅ NTAG213 (180 bytes)
✅ NTAG215 (540 bytes) 
✅ NTAG216 (924 bytes)
✅ Mifare Classic 1K/4K
✅ Mifare Ultralight
✅ ISO14443 Type A/B
✅ FeliCa (Android only)

Brazilian Features

CPF Validation:

• Real-time CPF format validation
• Mathematical verification
• Error handling with Portuguese messages
• Integration with user authentication

CEP Integration:

• Automatic address lookup
• Postal code validation
• Brazilian address formatting
• Integration with user registration

🧪 Testing

Run Tests

# Run all tests
flutter test

# Run with coverage
flutter test --coverage

# Run specific test file
flutter test test/unit/nfc_service_test.dart

# Integration tests (requires device)
flutter test integration_test/

NFC Testing Requirements

• Physical Device: NFC functionality requires real hardware
• NFC Tags: Various tag types for compatibility testing
• Test Environment: Isolated test codes to prevent conflicts
• Mock Services: Unit tests with mocked NFC operations

📝 License

This project is under the MIT license. See LICENSE for details.

🤝 Contributing

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

1. Fork the project
2. Create your feature branch (git checkout -b feature/SecureNFCFeature)
3. Commit your changes (git commit -m 'Add secure NFC writing feature')
4. Push to the branch (git push origin feature/SecureNFCFeature)
5. Open a Pull Request

⭐ Support

If you find this project helpful, please give it a star ⭐ to help others discover it!

For support or questions:

• 📧 Email: gabrielmaialva33@gmail.com
• 💬 Telegram: @mrootx
• 🐙 GitHub Issues: Create an issue

👥 Author

Made with ❤️ by Maia - Passionate about secure mobile solutions!

• 📧 Email: gabrielmaialva33@gmail.com
• 💬 Telegram: @mrootx
• 🐙 GitHub: @gabrielmaialva33

© 2017-present Maia