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Vanguard

# 使用Python实现一个简单的区块链下面是一个使用Python实现的基本区块链示例，包含区块结构、区块链、工作量证明和交易功能： ```python import hashlib import json import time from typing import List, Dict, Any from dataclasses import dataclass, asdict from datetime import datetime @dataclass class Transaction: """交易类""" sender: str receiver: str amount: float timestamp: float = None def __post_init__(self): if self.timestamp is None: self.timestamp = time.time() def to_dict(self) -> Dict[str, Any]: return asdict(self) class Block: """区块类""" def __init__(self, index: int, transactions: List[Transaction], previous_hash: str, timestamp: float = None, nonce: int = 0, difficulty: int = 4): self.index = index self.transactions = transactions self.timestamp = timestamp or time.time() self.previous_hash = previous_hash self.nonce = nonce self.difficulty = difficulty self.hash = self.calculate_hash() def calculate_hash(self) -> str: """计算区块的哈希值""" block_string = json.dumps({ 'index': self.index, 'transactions': [tx.to_dict() for tx in self.transactions], 'timestamp': self.timestamp, 'previous_hash': self.previous_hash, 'nonce': self.nonce, 'difficulty': self.difficulty }, sort_keys=True) return hashlib.sha256(block_string.encode()).hexdigest() def mine_block(self) -> None: """工作量证明：挖矿""" target = '0' * self.difficulty while self.hash[:self.difficulty] != target: self.nonce += 1 self.hash = self.calculate_hash() def is_valid(self) -> bool: """验证区块是否有效""" # 验证哈希值是否正确 if self.hash != self.calculate_hash(): return False # 验证工作量证明 target = '0' * self.difficulty if self.hash[:self.difficulty] != target: return False return True def to_dict(self) -> Dict[str, Any]: """将区块转换为字典""" return { 'index': self.index, 'transactions': [tx.to_dict() for tx in self.transactions], 'timestamp': self.timestamp, 'previous_hash': self.previous_hash, 'nonce': self.nonce, 'difficulty': self.difficulty, 'hash': self.hash } class Blockchain: """区块链类""" def __init__(self, difficulty: int = 4): self.chain: List[Block] = [] self.difficulty = difficulty self.pending_transactions: List[Transaction] = [] self.mining_reward = 10.0 # 创建创世区块 self.create_genesis_block() def create_genesis_block(self) -> None: """创建创世区块（第一个区块）""" genesis_block = Block( index=0, transactions=[], previous_hash="0" * 64, # 64个0 timestamp=time.time(), difficulty=self.difficulty ) genesis_block.mine_block() self.chain.append(genesis_block) def get_latest_block(self) -> Block: """获取最新的区块""" return self.chain[-1] def add_transaction(self, transaction: Transaction) -> None: """添加交易到待处理交易列表""" # 在实际的区块链中，这里应该验证交易的有效性 self.pending_transactions.append(transaction) def mine_pending_transactions(self, miner_address: str) -> None: """挖矿：将待处理交易打包成区块""" if not self.pending_transactions: print("没有待处理的交易") return # 添加矿工奖励交易 reward_transaction = Transaction( sender="系统", receiver=miner_address, amount=self.mining_reward ) self.pending_transactions.append(reward_transaction) # 创建新区块 new_block = Block( index=len(self.chain), transactions=self.pending_transactions.copy(), previous_hash=self.get_latest_block().hash, difficulty=self.difficulty ) print(f"开始挖矿区块 #{new_block.index}...") start_time = time.time() new_block.mine_block() end_time = time.time() print(f"区块 #{new_block.index} 挖矿完成!") print(f"耗时: {end_time - start_time:.2f} 秒") print(f"哈希值: {new_block.hash}") print(f"Nonce值: {new_block.nonce}") # 将新区块添加到链上 self.chain.append(new_block) # 清空待处理交易 self.pending_transactions = [] def is_chain_valid(self) -> bool: """验证整个区块链的有效性""" for i in range(1, len(self.chain)): current_block = self.chain[i] previous_block = self.chain[i-1] # 验证当前区块的有效性 if not current_block.is_valid(): print(f"区块 #{current_block.index} 无效") return False # 验证与前一个区块的链接 if current_block.previous_hash != previous_block.hash: print(f"区块 #{current_block.index} 的前一个哈希值不匹配") return False return True def get_balance(self, address: str) -> float: """获取地址的余额""" balance = 0.0 for block in self.chain: for transaction in block.transactions: if transaction.sender == address: balance -= transaction.amount if transaction.receiver == address: balance += transaction.amount return balance def display_chain(self) -> None: """显示整个区块链""" print("\n" + "="*80) print("区块链信息") print("="*80) print(f"区块数量: {len(self.chain)}") print(f"当前难度: {self.difficulty}") print(f"挖矿奖励: {self.mining_reward}") print("="*80) for block in self.chain: block_data = block.to_dict() print(f"\n区块 #{block_data['index']}:") print(f" 哈希值: {block_data['hash']}") print(f" 前一个哈希: {block_data['previous_hash']}") print(f" 时间戳: {datetime.fromtimestamp(block_data['timestamp']).strftime('%Y-%m-%d %H:%M:%S')}") print(f" Nonce值: {block_data['nonce']}") print(f" 难度: {block_data['difficulty']}") print(f" 交易数量: {len(block_data['transactions'])}") if block_data['transactions']: print(" 交易详情:") for tx in block_data['transactions']: print(f" {tx['sender']} -> {tx['receiver']}: {tx['amount']}") def main(): """主函数：演示区块链的基本功能""" print("创建区块链...") blockchain = Blockchain(difficulty=3) # 降低难度以便快速演示 # 添加一些交易 print("\n添加交易...") blockchain.add_transaction(Transaction("Alice", "Bob", 50.0)) blockchain.add_transaction(Transaction("Bob", "Charlie", 25.0)) blockchain.add_transaction(Transaction("Charlie", "Alice", 10.0)) # 挖矿（由矿工"Miner1"完成） print("\n开始挖矿...") blockchain.mine_pending_transactions("Miner1") # 添加更多交易 print("\n添加更多交易...") blockchain.add_transaction(Transaction("Alice", "David", 30.0)) blockchain.add_transaction(Transaction("David", "Eve", 15.0)) # 再次挖矿 print("\n开始第二次挖矿...") blockchain.mine_pending_transactions("Miner2") # 显示区块链 blockchain.display_chain() # 验证区块链 print(f"\n区块链是否有效: {blockchain.is_chain_valid()}") # 显示余额 print("\n地址余额:") addresses = ["Alice", "Bob", "Charlie", "David", "Eve", "Miner1", "Miner2"] for address in addresses: balance = blockchain.get_balance(address) print(f" {address}: {balance}") # 尝试篡改区块链（演示安全性） print("\n尝试篡改区块链...")

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