Hesar - Secure Message Encryption

A secure Android application for encrypting and decrypting messages with AES-256-GCM

English | فارسی

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📋 Table of Contents

• Features
• Screenshots
• Download
• Security
• Getting Started
• Usage
• Building from Source
• Technical Architecture
• Contributing
• License

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✨ Features

• 🔐 Military-Grade Encryption: AES-256-GCM encryption with PBKDF2 key derivation
• 🔑 Key Management: Generate, save, and share encryption keys securely
• 📱 Modern UI: Beautiful dark-themed interface with Persian language support
• 🌐 Persian Output Encoding: Converts encrypted data to Persian characters for easy sharing
• 💾 Persistent Storage: Automatically saves your encryption key for convenience
• 🚀 Optimized Performance: Split APK builds for minimal app size
• 🔄 Real-time Encryption: Instant encryption/decryption as you type
• 🎨 Material Design: Follows modern Android design guidelines

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📸 Screenshots

Encryption	Decryption	Key Management

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📥 Download

Latest Release

Download the latest version from the Releases page.

Choose the Right Version

Architecture	Description	Recommended For
arm64-v8a	64-bit ARM devices	Modern Android phones (2017+)
armeabi-v7a	32-bit ARM devices	Older Android phones
x86_64	64-bit Intel/AMD	Emulators, Chromebooks
x86	32-bit Intel/AMD	Older emulators
universal	All architectures	If unsure (larger file size)

Note: Most modern Android devices use arm64-v8a. If you're unsure, download the universal version.

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🔒 Security

Encryption Algorithm

Hesar uses AES-256-GCM (Advanced Encryption Standard with Galois/Counter Mode), which is:

• ✅ Approved by NIST and used by governments worldwide
• ✅ Provides both confidentiality and authenticity
• ✅ Resistant to known cryptographic attacks
• ✅ Industry standard for secure communications

Key Derivation

• PBKDF2 (Password-Based Key Derivation Function 2) with SHA-256
• 10,000 iterations to prevent brute-force attacks
• Each message uses a unique random IV (Initialization Vector)

Security Considerations

⚠️ Important Notes:

• Keep your encryption key safe and private
• Share keys only through secure channels (in person, encrypted messaging)
• Do not reuse keys across different applications
• This app is designed for personal use and moderate security needs
• For highly sensitive data, consider additional security layers

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🚀 Getting Started

Prerequisites

• Android device running Android 5.0 (API 21) or higher
• ~20 MB of free storage space

Installation

1. Download the appropriate APK for your device from Releases
2. Enable "Install from unknown sources" in your Android settings
3. Install the APK
4. Open Hesar and start encrypting!

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📖 Usage

First Time Setup

1. Open the app and navigate to the "Key" (کلید) tab
2. Generate a new key by clicking "Create New Key" button
   • Or enter your existing key manually
3. Save the key by clicking the "Save Key" button
4. Share the key with your intended recipient through a secure channel

Encrypting a Message

1. Navigate to the "Encryption" (رمزنگاری) tab
2. Type your message in the input field
3. The encrypted message appears automatically
4. Click "Copy" to copy the encrypted message
5. Share it through any messaging platform

Decrypting a Message

1. Make sure you have the correct key entered in the "Key" tab
2. Navigate to the "Decryption" (رمزگشایی) tab
3. Paste the encrypted message in the input field
4. The decrypted message appears automatically
5. Click "Copy" to copy the original message

Key Management

• Generate: Creates a random 32-character key
• Save: Stores the key locally for future use
• Copy: Copies the key to clipboard for sharing

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🛠 Building from Source

Prerequisites

• Flutter SDK: 3.24.5 or higher
• Android SDK: API level 21+
• Java: JDK 17
• Git: For cloning the repository

Setup

# Clone the repository
git clone https://github.com/CertMusashi/Dapp.git
cd Dapp

# Install dependencies
flutter pub get

# Run the app in debug mode
flutter run

# Build release APK (universal)
flutter build apk --release

# Build split APKs for smaller size
flutter build apk --release --split-per-abi

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🏗 Technical Architecture

Project Structure

lib/
└── main.dart          # Main application code with encryption logic

android/
├── app/
│   └── build.gradle   # Android build configuration with APK splitting
└── ...

.github/
└── workflows/
    ├── build.yml      # CI/CD for debug builds
    └── release.yml    # Release workflow with version management

Encryption Flow

User Input → PBKDF2 Key Derivation → AES-256-GCM Encryption
          → Base64 Encoding → Persian Character Mapping → Output

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🤝 Contributing

Contributions are welcome! Here's how you can help:

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

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📄 License

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

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📞 Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions

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Made with ❤️ for secure communications

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