105 lines
3.3 KiB
Python
105 lines
3.3 KiB
Python
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# Module 1 - Create a Blockchain
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# To be installed:
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# Flask==0.12.2: pip install Flask==0.12.2
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# Postman HTTP Client: https://www.getpostman.com/
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# Importing the libraries
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import datetime
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import hashlib
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import json
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from flask import Flask, jsonify
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# Part 1 - Building a Blockchain
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class Blockchain:
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def __init__(self):
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self.chain = []
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self.create_block(proof = 1, previous_hash = '0')
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def create_block(self, proof, previous_hash):
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block = {'index': len(self.chain) + 1,
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'timestamp': str(datetime.datetime.now()),
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'proof': proof,
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'previous_hash': previous_hash}
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self.chain.append(block)
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return block
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def get_previous_block(self):
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return self.chain[-1]
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def proof_of_work(self, previous_proof):
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new_proof = 1
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check_proof = False
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while check_proof is False:
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hash_operation = hashlib.sha256(str(new_proof**2 - previous_proof**2).encode()).hexdigest()
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if hash_operation[:4] == '0000':
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check_proof = True
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else:
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new_proof += 1
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return new_proof
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def hash(self, block):
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encoded_block = json.dumps(block, sort_keys = True).encode()
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return hashlib.sha256(encoded_block).hexdigest()
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def is_chain_valid(self, chain):
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previous_block = chain[0]
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block_index = 1
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while block_index < len(chain):
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block = chain[block_index]
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if block['previous_hash'] != self.hash(previous_block):
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return False
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previous_proof = previous_block['proof']
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proof = block['proof']
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hash_operation = hashlib.sha256(str(proof**2 - previous_proof**2).encode()).hexdigest()
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if hash_operation[:4] != '0000':
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return False
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previous_block = block
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block_index += 1
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return True
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# Part 2 - Mining our Blockchain
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# Creating a Web App
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app = Flask(__name__)
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# Creating a Blockchain
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blockchain = Blockchain()
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# Mining a new block
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@app.route('/mine_block', methods = ['GET'])
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def mine_block():
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previous_block = blockchain.get_previous_block()
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previous_proof = previous_block['proof']
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proof = blockchain.proof_of_work(previous_proof)
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previous_hash = blockchain.hash(previous_block)
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block = blockchain.create_block(proof, previous_hash)
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response = {'message': 'Congratulations, you just mined a block!',
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'index': block['index'],
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'timestamp': block['timestamp'],
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'proof': block['proof'],
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'previous_hash': block['previous_hash']}
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return jsonify(response), 200
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# Getting the full Blockchain
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@app.route('/get_chain', methods = ['GET'])
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def get_chain():
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response = {'chain': blockchain.chain,
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'length': len(blockchain.chain)}
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return jsonify(response), 200
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# Checking if the Blockchain is valid
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@app.route('/is_valid', methods = ['GET'])
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def is_valid():
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is_valid = blockchain.is_chain_valid(blockchain.chain)
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if is_valid:
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response = {'message': 'All good. The Blockchain is valid.'}
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else:
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response = {'message': 'Houston, we have a problem. The Blockchain is not valid.'}
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return jsonify(response), 200
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# Running the app
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app.run(host = '0.0.0.0', port = 5000)
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