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blockchain.py
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blockchain.py
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#Importing the libraries
import datetime
import hashlib
import json
from flask import Flask, jsonify
#Building a Blockchain
class Blockchain:
def __init__(self):
self.chain=[]
self.create_block(proof=1, previous_hash='0')
def create_block(self, proof, previous_hash):
block={'index': len(self.chain)+1,
'timestamp': str(datetime.datetime.now()),
'proof': proof,
'prev_hash': previous_hash}
self.chain.append(block)
return block
def get_previous_block(self):
prev_block=self.chain[-1]
return prev_block
def proof_of_work(self, previous_proof):
new_proof=1
check_proof=False
while check_proof is False:
hash_operation=hashlib.sha256(str(new_proof**2-previous_proof**2).encode()).hexdigest()
if hash_operation[:4]=='0000':
check_proof=True
else:
new_proof+=1
return new_proof
def hash(self, block):
encoded_block=json.dumps(block, sort_keys=True).encode()
return hashlib.sha256(encoded_block).hexdigest()
def is_chain_valid(self, chain):
previous_block=chain[0]
block_index=1
while block_index<len(chain):
block=chain[block_index]
if block['previous_hash']!=self.hash(previous_block):
return False
previous_proof=previous_block['proof']
proof=block['proof']
hash_operation=hashlib.sha256(str(proof**2-previous_proof**2).encode()).hexdigest()
if hash_operation[:4]!='0000':
return False
previous_block=block
block_index+=1
return True
#Mining our Blockchain
#Creating a Web application
app=Flask(__name__)
#Creating a Blockchain
blockchain=Blockchain()
#Mining a block
@app.route('/mine_block', methods=['GET'])
def mine_block():
previous_block=blockchain.get_previous_block()
previous_proof=previous_block['proof']
proof=blockchain.proof_of_work(previous_proof)
previous_hash=blockchain.hash(previous_block)
block=blockchain.create_block(proof, previous_hash)
response={'message':'Congratulations! You just mined a block.',
'index':block['index'],
'timestamp':block['timestamp'],
'proof':block['proof'],
'previous_hash':block['previous_hash']}
return jsonify(response), 200
#Getting the full Blockchain
@app.route('/get_chain', methods=['GET'])
def get_chain():
response={'chain':blockchain.chain,
'length':len(blockchain.chain)}
return jsonify(response), 200