BlockWallet

BlockWallet is a decentralized wallet application built with Flutter for the frontend and Node.js (Express) for the backend. It supports secure Ethereum transactions, QR code payments, username-based transfers, and privacy-preserving zero-knowledge proof (ZKP) features.

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Table of Contents

• Features
• Architecture
• Getting Started
  • Flutter Frontend
  • Node.js Backend
• Configuration
• Usage
• Terms & Conditions
• License

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Features

• 🦄 Modern Flutter UI: Cross-platform, responsive, and beautiful.
• 🔒 Ethereum Wallet: Send/receive ETH, view balances, and transaction history.
• 🧑‍💻 Username-based Transfers: Send ETH using usernames instead of addresses.
• 📱 QR Code Support: Scan and generate QR codes for wallet addresses.
• 🕵️ Zero-Knowledge Proofs: Privacy-preserving transactions using ZKP.
• 🗄️ Local Storage: Transaction history stored securely with Hive.
• 🌐 Backend API: Node.js server for user management and ZKP proof generation.

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Architecture

Flutter (Frontend) <----> Node.js/Express (Backend) <----> Ethereum Blockchain

• Flutter: Handles wallet UI, QR, and user interactions.
• Node.js/Express: Provides REST APIs for user lookup, ZKP proof generation, and interacts with Ethereum via Web3.
• PostgreSQL: (Optional) Used for storing user <-> address mappings.

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Getting Started

Flutter Frontend

1. Install Flutter: Flutter Install Guide
2. Clone the repository:

   git clone https://github.com/yourusername/blockwallet.git
   cd blockwallet

3. Install dependencies:

   flutter pub get

4. Run the app:

   flutter run

Node.js Backend

1. Install Node.js: Node.js Download
2. Install dependencies:

   cd backend
   npm install

3. Configure environment variables (see .env.example or set directly in code).
4. Start the server:

   node zkpBackend.js

   For username/address API:

   node ganache/fetchUsername.js

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Configuration

• Flutter: Edit lib/services/ethereum_service.dart to set your Ethereum RPC URL, private key, and contract address.
• Backend: Set your Ganache/Infura RPC URL, contract ABI/address, and PostgreSQL credentials in the backend files or via environment variables.

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Usage

• Send ETH: Enter a username or address, specify amount, and send.
• Receive ETH: Share your QR code or address.
• Transaction History: View all past transactions in the app.
• Privacy: ZKP is used for privacy-preserving transactions (backend must be running).

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Terms & Conditions

By using BlockWallet, you agree to the following terms:

1. No Warranty: BlockWallet is provided "as is" without warranty of any kind. Use at your own risk.
2. Security: You are responsible for safeguarding your private keys and credentials. The developers are not liable for any loss of funds.
3. Open Source: This project is open source and intended for educational and experimental purposes. Do not use with mainnet funds.
4. Privacy: No personal data is collected by the app. All sensitive operations are performed locally or on your chosen backend.
5. Compliance: You are responsible for complying with local laws and regulations regarding cryptocurrency usage.

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License

This project is licensed under the MIT License.

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Contributing

Pull requests are welcome! For major changes, please open an issue first to discuss what you would like to change.

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Contact

For support or questions, open an issue or contact thangarajk176@example.com.