CARE/blockchain.py at master · snocoder/CARE · 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
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
import datetime
import hashlib
import json
from flask import Flask, jsonify, request

# Building BlockChain

class Blockchain:
    def __init__(self):
        self.chain = []
        self.create_block(proof = 1, previous_hash = '0', data = 'zero')

    def create_block(self, proof, previous_hash, data):
        block = {'index' : len(self.chain) + 1,
                 'timestamp' : str(datetime.datetime.now()),
                 'proof' : proof,
                 'data' : data,
                 '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()


#http://localhost:5000/mine_block/name=bharath

@app.route('/mine_block/name=<username>/address=<address>', methods = ['GET', 'POST'])
def mine_block(username, address):
    previous_block = blockchain.get_previous_block()
    previous_proof = previous_block['proof']
    proof = blockchain.proof_of_work(previous_proof)
    previous_hash = blockchain.hash(previous_block)
    data = "Name : " + username + ", Address : " + address
    block = blockchain.create_block(proof, previous_hash, data)

    response = {'message' : 'Congo You just Mined a block',
                'index' : block['index'],
                'data' : block['data'],
                '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.route('/is_valid', methods = ['GET'])
def is_valid():
    valid = blockchain.is_chain_valid(blockchain.chain)
    if valid:
        response = {'message' : 'Chain is valid.'}
    else:
        response = {'message' : 'Chain is not valid.'}
    return jsonify(response), 200


app.run(port = 5000)