A complete blockchain implementation in Python with Flask web interface, featuring cryptocurrency transactions, digital signatures, proof-of-work mining, and a distributed network architecture.

• Complete Blockchain: Full blockchain implementation with blocks, transactions, and chain validation
• Digital Signatures: RSA-based transaction signing and verification using SHA-256
• Proof of Work: Mining algorithm with adjustable difficulty
• Wallet System: Generate wallets, create and sign transactions
• Network Nodes: Distributed network with consensus algorithm
• REST API: Complete REST API for blockchain operations
• Web Interface: User-friendly web interface for interaction
• Security: Enhanced security with 2048-bit RSA keys and SHA-256 hashing

The project consists of two main components:

• Core blockchain functionality
• Mining and proof-of-work
• Transaction validation
• Network consensus
• REST API endpoints

• Wallet generation and management
• Transaction creation and signing
• Transaction verification
• Client interface for interacting with blockchain nodes

• Python 3.7+
• pip package manager

pip install flask flask-cors pycryptodome requests

git clone <your-repository-url>
cd blockchain-project

# Start blockchain node on default port 5000
python blockchain.py

# Start on custom port
python blockchain.py -p 5001

# Start in debug mode
python blockchain.py --debug

# Start client on default port 8080
python blockchain_client.py

# Start on custom port
python blockchain_client.py -p 8081

# Start in debug mode
python blockchain_client.py --debug

curl http://localhost:8080/wallet/new

curl -X POST http://localhost:8080/generate/transaction \
  -H "Content-Type: application/json" \
  -d '{
    "sender_address": "your_public_key",
    "sender_private_key": "your_private_key",
    "recipient_address": "recipient_public_key",
    "amount": 10
  }'

curl -X POST http://localhost:5000/transactions/new \
  -H "Content-Type: application/json" \
  -d '{
    "sender_address": "sender_public_key",
    "recipient_address": "recipient_public_key",
    "amount": 10,
    "signature": "transaction_signature"
  }'

curl http://localhost:5000/mine

curl http://localhost:5000/chain

MINING_SENDER = "THE BLOCKCHAIN"
MINING_REWARD = 1
MINING_DIFFICULTY = 2  # Number of leading zeros required

• RSA-2048: 2048-bit RSA keys for enhanced security
• SHA-256: Secure hashing algorithm for signatures and blocks
• Input Validation: Comprehensive input validation and error handling
• Logging: Detailed logging for debugging and monitoring

1. Start first node:

python blockchain.py -p 5000

2. Start second node:

python blockchain.py -p 5001

3. Register nodes with each other:

# Register node 5001 with node 5000
curl -X POST http://localhost:5000/nodes/register \
  -H "Content-Type: application/json" \
  -d '{"nodes": ["127.0.0.1:5001"]}'

# Register node 5000 with node 5001
curl -X POST http://localhost:5001/nodes/register \
  -H "Content-Type: application/json" \
  -d '{"nodes": ["127.0.0.1:5000"]}'

4. Resolve conflicts:

curl http://localhost:5000/nodes/resolve
curl http://localhost:5001/nodes/resolve

blockchain-project/
├── blockchain.py           # Main blockchain node
├── blockchain_client.py    # Blockchain client/wallet
├── templates/             # HTML templates
│   ├── index.html
│   ├── configure.html
│   ├── make_transaction.html
│   └── view_transactions.html
└── README.md

• Private Key Management: Store private keys securely
• Network Security: Use HTTPS in production
• Input Validation: All inputs are validated and sanitized
• Error Handling: Comprehensive error handling prevents crashes
• Signature Verification: All transactions are cryptographically verified

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

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

1. Port Already in Use

   # Use different port
   python blockchain.py -p 5002

2. Missing Dependencies

   pip install flask flask-cors pycryptodome requests

3. Connection Refused

   • Ensure blockchain node is running before starting client
   • Check firewall settings
   • Verify correct ports are being used

Both applications provide detailed logging. Check console output for debugging information.

• Mining Difficulty: Adjust MINING_DIFFICULTY based on desired block time
• Key Size: 2048-bit RSA keys provide good security vs performance balance
• Network Latency: Consider network delays when running distributed nodes

• Database persistence
• Enhanced web interface
• Smart contracts
• Multi-signature transactions
• Transaction fees
• Block size limits
• Performance optimizations

For questions or issues, please open an issue on GitHub or contact the maintainers.

Note: This is an educational blockchain implementation. For production use, additional security measures and optimizations would be required.