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| import hashlib | |
| import time | |
| class Block: | |
| def __init__(self, index, previous_hash, timestamp, data, hash): | |
| self.index = index | |
| self.previous_hash = previous_hash | |
| self.timestamp = timestamp | |
| self.data = data | |
| self.hash = hash | |
| class Blockchain: | |
| def __init__(self): | |
| self.chain = [self.create_genesis_block()] | |
| def create_genesis_block(self): | |
| genesis_block = Block(0, "0", int(time.time()), "Genesis Block", "0") | |
| genesis_block.hash = self.calculate_hash(genesis_block) | |
| return genesis_block | |
| def calculate_hash(self, block): | |
| block_string = f"{block.index}{block.previous_hash}{block.timestamp}{block.data}".encode() | |
| return hashlib.sha256(block_string).hexdigest() | |
| def get_latest_block(self): | |
| return self.chain[-1] | |
| def add_block(self, data): | |
| latest_block = self.get_latest_block() | |
| new_block = Block(len(self.chain), latest_block.hash, int(time.time()), data, "") | |
| new_block.hash = self.calculate_hash(new_block) | |
| self.chain.append(new_block) | |
| print(f"Block added: {new_block.hash}") | |
| return new_block | |
| def is_chain_valid(self): | |
| for i in range(1, len(self.chain)): | |
| current_block = self.chain[i] | |
| previous_block = self.chain[i - 1] | |
| if current_block.hash != self.calculate_hash(current_block): | |
| return False | |
| if current_block.previous_hash != previous_block.hash: | |
| return False | |
| return True | |