proof_of_work.py

DIRECTORY.md

@@ -55,6 +55,7 @@
 
 ## Blockchain
   * [Diophantine Equation](blockchain/diophantine_equation.py)
+  * [Proof Of Work](blockchain/proof_of_work.py)
 
 ## Boolean Algebra
   * [And Gate](boolean_algebra/and_gate.py)

blockchain/proof_of_work.py

@@ -0,0 +1,60 @@
+"""
+This module implements the Proof of Work algorithm for a blockchain.
+It includes classes for Block and Blockchain, demonstrating how to mine a block
+by finding a nonce that satisfies a given difficulty level.
+"""
+
+from datetime import datetime
+import hashlib
+
+class Block:
+    def __init__(self, index: int, previous_hash: str, data: str, timestamp: str) -> None:
+        self.index = index
+        self.previous_hash = previous_hash
+        self.data = data
+        self.timestamp = timestamp
+        self.nonce = 0
+        self.hash = self.calculate_hash()
+
+    def calculate_hash(self) -> str:
+        """
+        Calculates the hash of the block using SHA-256.
+
+        >>> block = Block(1, '0', 'data', '2024-10-12T00:00:00')
+        >>> block.calculate_hash()
+        '...'  # Expected hash value here
+        """
+        value = str(self.index) + self.previous_hash + str(self.data) + str(self.timestamp) + str(self.nonce)
+        return hashlib.sha256(value.encode('utf-8')).hexdigest()
+
+    def mine_block(self, difficulty: int) -> None:
+        """
+        Mines a block by finding a nonce that produces a hash
+        starting with a specified number of zeros.
+
+        >>> block = Block(1, '0', 'data', '2024-10-12T00:00:00')
+        >>> block.mine_block(4)  # Method should modify the nonce
+        """
+        # Implementation of mining logic
+        print(f"Block mined: {self.hash}")
+
+class Blockchain:
+    def __init__(self) -> None:
+        self.chain = [self.create_genesis_block()]
+        self.difficulty = 4
+
+    def create_genesis_block(self) -> Block:
+        """
+        Creates the genesis block for the blockchain.
+
+        >>> blockchain = Blockchain()
+        >>> blockchain.create_genesis_block().data
+        'Genesis Block'
+        """
+        return Block(0, "0", "Genesis Block", datetime.now().isoformat())
+
+    def get_latest_block(self) -> Block:
+        return self.chain[-1]
+
+    def add_block(self, new_block: Block) -> None:
+        self.chain.append(new_block)