🔗 Python Blockchain Implementation

A fully functional blockchain cryptocurrency system built with Python and Flask, featuring proof-of-work consensus, digital wallets, and peer-to-peer networking.

🚀 Live Demo

Try the live blockchain app →

✨ Features

Core Blockchain Functionality

• Proof-of-Work Consensus: Secure mining with adjustable difficulty
• Digital Wallets: RSA key pair generation and management
• Transaction System: Cryptographically signed transactions
• Peer-to-Peer Network: Multi-node blockchain synchronization
• Conflict Resolution: Longest chain rule implementation

Web Interface

• Interactive Dashboard: Real-time blockchain monitoring
• Wallet Management: Create/load wallets with balance tracking
• Transaction Processing: Send/receive cryptocurrency
• Network Visualization: View connected peer nodes
• Mining Interface: Mine new blocks and earn rewards

Technical Highlights

• RESTful API with comprehensive endpoints
• Persistent data storage (JSON-based)
• Bootstrap-responsive web UI
• Modular architecture with proper separation of concerns
• Production-ready with Heroku deployment configuration

🛠️ Technology Stack

• Backend: Python 3.9, Flask, Flask-CORS
• Cryptography: PyCrypto (RSA signatures, SHA-256 hashing)
• Frontend: HTML5, CSS3, Bootstrap 4, Vanilla JavaScript
• Deployment: Gunicorn WSGI server
• Networking: HTTP REST API, JSON data exchange

🏃‍♂️ Quick Start

Prerequisites

• Python 3.9+
• pip package manager

Installation

1. Clone the repository

   git clone https://github.com/yourusername/blockchain-project.git
   cd blockchain-project

2. Install dependencies

   pip install -r requirements.txt

3. Run a single node

   python node.py

   Access the web interface at http://localhost:5000

Multi-Node Network

Run multiple nodes to test peer-to-peer functionality:

# Terminal 1 - Node on port 5000
python node.py --port 5000

# Terminal 2 - Node on port 5001  
python node.py --port 5001

# Terminal 3 - Node on port 5002
python node.py --port 5002

Connect nodes via the web interface to create a distributed network.

📊 API Documentation

Wallet Operations

• POST /wallet - Create new wallet keys
• GET /wallet - Load existing wallet

Transaction Management

• POST /transaction - Submit new transaction
• GET /transactions - Get pending transactions

Blockchain Operations

• GET /chain - Retrieve full blockchain
• POST /mine - Mine a new block
• POST /resolve-conflicts - Synchronize with network

Network Management

• POST /node - Add peer node
• GET /nodes - List connected peers
• DELETE /node/<node_id> - Remove peer node

🏗️ Architecture Overview

┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   Web UI        │    │   Flask API     │    │   Blockchain    │
│   (Bootstrap)   │◄──►│   (REST)        │◄──►│   Core Logic    │
└─────────────────┘    └─────────────────┘    └─────────────────┘
                                │
                       ┌─────────────────┐
                       │   Utilities     │
                       │   - Hash Utils  │
                       │   - Verification│
                       │   - Crypto      │
                       └─────────────────┘

Key Components

• blockchain.py: Core blockchain logic and consensus algorithm
• node.py: Flask REST API server and routing
• wallet.py: RSA cryptography and key management
• transaction.py: Transaction data structures
• block.py: Block data structures
• utility/: Hashing, verification, and helper functions

🧪 Testing the Application

1. Create a wallet - Generate RSA key pairs
2. Mine blocks - Earn initial cryptocurrency
3. Send transactions - Transfer funds between wallets
4. Add peer nodes - Test network synchronization
5. Resolve conflicts - Verify longest chain consensus

🚀 Deployment

The application is configured for production deployment with:

• Heroku: Ready-to-deploy with Procfile and runtime.txt
• Railway/Render: Modern cloud platforms with Git integration
• Environment Variables: Configurable port and settings

Deploy to Heroku

heroku create your-blockchain-app
git push heroku main

🔐 Security Features

• Digital Signatures: All transactions cryptographically signed
• Hash Verification: Block integrity through SHA-256 chaining
• Proof-of-Work: Prevents double-spending and spam
• Input Validation: Comprehensive request validation
• Key Security: Private keys stored locally, never transmitted

📈 Performance Considerations

• Mining Difficulty: Adjustable proof-of-work complexity
• Data Persistence: Efficient JSON-based storage
• Network Optimization: Minimal bandwidth peer communication
• Scalability: Modular design supports feature expansion

🤝 Contributing

This project demonstrates core blockchain concepts and is open for improvements:

1. Fork the repository
2. Create a feature branch
3. Implement your changes
4. Add tests if applicable
5. Submit a pull request

📝 License

This project is open source and available under the MIT License.

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Built to demonstrate blockchain technology, cryptographic principles, and full-stack development skills.