Python Blockchain

Blockchain implementation using Python.

What I learned

• How to implement blockchain.
• What is Proof of Work.
• How to use Flask.

Prerequisites

• python3
• pipenv

How to start nodes

1. Install dependencies.

   pipenv install

2. Activate virtualenv.

   pipenv shell

3. Start node 1.

   python3 -m server 5000

4. Start node 2 on a different port in a different window.

   pipenv shell
   python3 -m server 5001

Usage

# Create a new transaction.
curl -X POST -H "Content-Type: application/json" -d '{
 "sender": "d4ee26eee15148ee92c6cd394edd974e",
 "recipient": "someone-other-address",
 "amount": 5
}' "http://localhost:5000/transactions/new"

# Mine a new block.
curl "http://localhost:5000/mine"

# Get the blockchain.
curl "http://localhost:5000/chain"

# Register node 2 on node 1.
curl -X POST -H "Content-Type: application/json" -d '{
   "nodes": ["http://localhost:5001"]
}' "http://localhost:5000/nodes/register"

# Mine some new blocks on node 2.
curl "http://localhost:5001/mine"
curl "http://localhost:5001/mine"
curl "http://localhost:5001/mine"

# Get the blockchain of node 2.
curl "http://localhost:5000/chain"

# Replace the blockchain of node 1 with that of node 2 by the Consensus Algorithm.
curl "http://localhost:5000/nodes/resolve"

# Get the blockchain of node 1. 
curl "http://localhost:5000/chain"

References

• https://hackernoon.com/learn-blockchains-by-building-one-117428612f46
• https://qiita.com/hidehiro98/items/841ece65d896aeaa8a2a