├── .gitattributes
├── README.md
└── blockchain.py


/.gitattributes:
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1 | # Auto detect text files and perform LF normalization
2 | * text=auto


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/README.md:
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1 | Simple Python Blockchain with MINING!
2 | =====================================
3 | 
4 | This is the source code for howCode's simple Python Blockchain.
5 | 
6 | You can watch the video that accompanies this source code here: https://youtu.be/b81Ib_oYbFk
7 | 


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/blockchain.py:
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 1 | import datetime
 2 | import hashlib
 3 | 
 4 | class Block:
 5 |     blockNo = 0
 6 |     data = None
 7 |     next = None
 8 |     hash = None
 9 |     nonce = 0
10 |     previous_hash = 0x0
11 |     timestamp = datetime.datetime.now()
12 | 
13 |     def __init__(self, data):
14 |         self.data = data
15 | 
16 |     def hash(self):
17 |         h = hashlib.sha256()
18 |         h.update(
19 |         str(self.nonce).encode('utf-8') +
20 |         str(self.data).encode('utf-8') +
21 |         str(self.previous_hash).encode('utf-8') +
22 |         str(self.timestamp).encode('utf-8') +
23 |         str(self.blockNo).encode('utf-8')
24 |         )
25 |         return h.hexdigest()
26 | 
27 |     def __str__(self):
28 |         return "Block Hash: " + str(self.hash()) + "\nBlockNo: " + str(self.blockNo) + "\nBlock Data: " + str(self.data) + "\nHashes: " + str(self.nonce) + "\n--------------"
29 | 
30 | class Blockchain:
31 | 
32 |     diff = 20
33 |     maxNonce = 2**32
34 |     target = 2 ** (256-diff)
35 | 
36 |     block = Block("Genesis")
37 |     dummy = head = block
38 | 
39 |     def add(self, block):
40 | 
41 |         block.previous_hash = self.block.hash()
42 |         block.blockNo = self.block.blockNo + 1
43 | 
44 |         self.block.next = block
45 |         self.block = self.block.next
46 | 
47 |     def mine(self, block):
48 |         for n in range(self.maxNonce):
49 |             if int(block.hash(), 16) <= self.target:
50 |                 self.add(block)
51 |                 print(block)
52 |                 break
53 |             else:
54 |                 block.nonce += 1
55 | 
56 | blockchain = Blockchain()
57 | 
58 | for n in range(10):
59 |     blockchain.mine(Block("Block " + str(n+1)))
60 | 
61 | while blockchain.head != None:
62 |     print(blockchain.head)
63 |     blockchain.head = blockchain.head.next
64 | 


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