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@Eversmile12
Created January 28, 2022 10:51
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Python Blockchain
# Python program to create Blockchain
# For timestamp
import datetime
# Calculating the hash
# in order to add digital
# fingerprints to the blocks
import hashlib
# To store data
# in our blockchain
import json
# Flask is for creating the web
# app and jsonify is for
# displaying the blockchain
from flask import Flask, jsonify
class Blockchain:
# This function is created
# to create the very first
# block and set it's hash to "0"
def __init__(self):
self.chain = []
self.create_block(proof=1, previous_hash='0')
# This function is created
# to add further blocks
# into the chain
def create_block(self, proof, previous_hash):
block = {'index': len(self.chain) + 1,
'timestamp': str(datetime.datetime.now()),
'proof': proof,
'previous_hash': previous_hash}
self.chain.append(block)
return block
# This function is created
# to display the previous block
def print_previous_block(self):
return self.chain[-1]
# This is the function for proof of work
# and used to successfully mine the 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[:5] == '00000':
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 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[:5] != '00000':
return False
previous_block = block
block_index += 1
return True
# Creating the Web
# App using flask
app = Flask(__name__)
# Create the object
# of the class blockchain
blockchain = Blockchain()
# Mining a new block
@app.route('/mine_block', methods=['GET'])
def mine_block():
previous_block = blockchain.print_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': 'A block is MINED',
'index': block['index'],
'timestamp': block['timestamp'],
'proof': block['proof'],
'previous_hash': block['previous_hash']}
return jsonify(response), 200
# Display blockchain in json format
@app.route('/get_chain', methods=['GET'])
def display_chain():
response = {'chain': blockchain.chain,
'length': len(blockchain.chain)}
return jsonify(response), 200
# Check validity of blockchain
@app.route('/valid', methods=['GET'])
def valid():
valid = blockchain.chain_valid(blockchain.chain)
if valid:
response = {'message': 'The Blockchain is valid.'}
else:
response = {'message': 'The Blockchain is not valid.'}
return jsonify(response), 200
# Run the flask server locally
app.run()
@Isaiah-Mwinga
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Great one bro

@yefreescoding
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Cool... highly appreciate it.

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