├── README.md
└── crypto.py


/README.md:
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1 | # Create-Cryptocurrency-in-Python
2 | This is the code for creating a simple cryptocurrency using the Python programming language
3 | 


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/crypto.py:
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  1 | import hashlib
  2 | import time
  3 | 
  4 | 
  5 | class Block:
  6 | 
  7 |     def __init__(self, index, proof_no, prev_hash, data, timestamp=None):
  8 |         self.index = index
  9 |         self.proof_no = proof_no
 10 |         self.prev_hash = prev_hash
 11 |         self.data = data
 12 |         self.timestamp = timestamp or time.time()
 13 | 
 14 |     @property
 15 |     def calculate_hash(self):
 16 |         block_of_string = "{}{}{}{}{}".format(self.index, self.proof_no,
 17 |                                               self.prev_hash, self.data,
 18 |                                               self.timestamp)
 19 | 
 20 |         return hashlib.sha256(block_of_string.encode()).hexdigest()
 21 | 
 22 |     def __repr__(self):
 23 |         return "{} - {} - {} - {} - {}".format(self.index, self.proof_no,
 24 |                                                self.prev_hash, self.data,
 25 |                                                self.timestamp)
 26 | 
 27 | 
 28 | class BlockChain:
 29 | 
 30 |     def __init__(self):
 31 |         self.chain = []
 32 |         self.current_data = []
 33 |         self.nodes = set()
 34 |         self.construct_genesis()
 35 | 
 36 |     def construct_genesis(self):
 37 |         self.construct_block(proof_no=0, prev_hash=0)
 38 | 
 39 |     def construct_block(self, proof_no, prev_hash):
 40 |         block = Block(
 41 |             index=len(self.chain),
 42 |             proof_no=proof_no,
 43 |             prev_hash=prev_hash,
 44 |             data=self.current_data)
 45 |         self.current_data = []
 46 | 
 47 |         self.chain.append(block)
 48 |         return block
 49 | 
 50 |     @staticmethod
 51 |     def check_validity(block, prev_block):
 52 |         if prev_block.index + 1 != block.index:
 53 |             return False
 54 | 
 55 |         elif prev_block.calculate_hash != block.prev_hash:
 56 |             return False
 57 | 
 58 |         elif not BlockChain.verifying_proof(block.proof_no,
 59 |                                             prev_block.proof_no):
 60 |             return False
 61 | 
 62 |         elif block.timestamp <= prev_block.timestamp:
 63 |             return False
 64 | 
 65 |         return True
 66 | 
 67 |     def new_data(self, sender, recipient, quantity):
 68 |         self.current_data.append({
 69 |             'sender': sender,
 70 |             'recipient': recipient,
 71 |             'quantity': quantity
 72 |         })
 73 |         return True
 74 | 
 75 |     @staticmethod
 76 |     def proof_of_work(last_proof):
 77 |         '''this simple algorithm identifies a number f' such that hash(ff') contain 4 leading zeroes
 78 |          f is the previous f'
 79 |          f' is the new proof
 80 |         '''
 81 |         proof_no = 0
 82 |         while BlockChain.verifying_proof(proof_no, last_proof) is False:
 83 |             proof_no += 1
 84 | 
 85 |         return proof_no
 86 | 
 87 |     @staticmethod
 88 |     def verifying_proof(last_proof, proof):
 89 |         #verifying the proof: does hash(last_proof, proof) contain 4 leading zeroes?
 90 | 
 91 |         guess = f'{last_proof}{proof}'.encode()
 92 |         guess_hash = hashlib.sha256(guess).hexdigest()
 93 |         return guess_hash[:4] == "0000"
 94 | 
 95 |     @property
 96 |     def latest_block(self):
 97 |         return self.chain[-1]
 98 | 
 99 |     def block_mining(self, details_miner):
100 | 
101 |         self.new_data(
102 |             sender="0",  #it implies that this node has created a new block
103 |             recipient=details_miner,
104 |             quantity=
105 |             1,  #creating a new block (or identifying the proof number) is awarded with 1
106 |         )
107 | 
108 |         last_block = self.latest_block
109 | 
110 |         last_proof_no = last_block.proof_no
111 |         proof_no = self.proof_of_work(last_proof_no)
112 | 
113 |         last_hash = last_block.calculate_hash
114 |         block = self.construct_block(proof_no, last_hash)
115 | 
116 |         return vars(block)
117 | 
118 |     def create_node(self, address):
119 |         self.nodes.add(address)
120 |         return True
121 | 
122 |     @staticmethod
123 |     def obtain_block_object(block_data):
124 |         #obtains block object from the block data
125 | 
126 |         return Block(
127 |             block_data['index'],
128 |             block_data['proof_no'],
129 |             block_data['prev_hash'],
130 |             block_data['data'],
131 |             timestamp=block_data['timestamp'])
132 | 
133 | 
134 | blockchain = BlockChain()
135 | 
136 | print("***Mining fccCoin about to start***")
137 | print(blockchain.chain)
138 | 
139 | last_block = blockchain.latest_block
140 | last_proof_no = last_block.proof_no
141 | proof_no = blockchain.proof_of_work(last_proof_no)
142 | 
143 | blockchain.new_data(
144 |     sender="0",  #it implies that this node has created a new block
145 |     recipient="Quincy Larson",  #let's send Quincy some coins!
146 |     quantity=
147 |     1,  #creating a new block (or identifying the proof number) is awarded with 1
148 | )
149 | 
150 | last_hash = last_block.calculate_hash
151 | block = blockchain.construct_block(proof_no, last_hash)
152 | 
153 | print("***Mining fccCoin has been successful***")
154 | print(blockchain.chain)
155 | 


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