BlockChain/blockchain.py at master · vaibhav2610/BlockChain · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
# -*- coding: utf-8 -*-
"""
Created on Mon Jul 16 12:27:38 2018

@author: Vaibhav
"""
import datetime
import hashlib
import json
from flask import Flask,jsonify

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,
                 'previous_hash' : previous_hash}
        self.chain.append(block)
        return block

    def get_previous_block(self):
       return self.chain[-1]

    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

app = Flask(__name__)
blockchain = Blockchain()
@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

@app.route('/get_chain',methods = ['GET'])
def get_chain():
    response = {'chain' : blockchain.chain,
                'length' : len(blockchain.chain)}
    return jsonify(response),200

app.run(host = '0.0.0.0', port = 5000)