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# 使用Python实现一个简单的区块链下面是一个使用Python实现的基础区块链示例，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 datetime import datetime from uuid import uuid4 class Block: """区块类""" def __init__(self, index: int, transactions: List[Dict], timestamp: float, previous_hash: str, nonce: int = 0): self.index = index self.transactions = transactions self.timestamp = timestamp self.previous_hash = previous_hash self.nonce = nonce 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": self.transactions, "timestamp": self.timestamp, "previous_hash": self.previous_hash, "nonce": self.nonce }, sort_keys=True).encode() return hashlib.sha256(block_string).hexdigest() def __repr__(self) -> str: return f"Block(index={self.index}, hash={self.hash[:10]}..., previous_hash={self.previous_hash[:10]}..., transactions={len(self.transactions)})" class Blockchain: """区块链类""" def __init__(self, difficulty: int = 4): self.chain: List[Block] = [] self.difficulty = difficulty # 挖矿难度，表示哈希值前导零的数量 self.pending_transactions: List[Dict] = [] self.mining_reward = 10 # 挖矿奖励 # 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(0, [], time.time(), "0") genesis_block.hash = genesis_block.calculate_hash() self.chain.append(genesis_block) def get_latest_block(self) -> Block: """获取最新的区块""" return self.chain[-1] def mine_pending_transactions(self, miner_address: str) -> None: """挖矿：将待处理交易打包成区块""" # 添加挖矿奖励交易 reward_transaction = { "from": "network", "to": miner_address, "amount": self.mining_reward, "timestamp": time.time(), "id": str(uuid4()) } self.pending_transactions.append(reward_transaction) # 创建新区块 block = Block( index=len(self.chain), transactions=self.pending_transactions, timestamp=time.time(), previous_hash=self.get_latest_block().hash ) # 工作量证明 block = self.proof_of_work(block) # 将区块添加到链上 self.chain.append(block) # 清空待处理交易 self.pending_transactions = [] def proof_of_work(self, block: Block) -> Block: """工作量证明算法""" target = "0" * self.difficulty while block.hash[:self.difficulty] != target: block.nonce += 1 block.hash = block.calculate_hash() print(f"区块 {block.index} 挖矿成功！Nonce: {block.nonce}, Hash: {block.hash}") return block def add_transaction(self, transaction: Dict) -> None: """添加新的交易到待处理交易列表""" # 简单的交易验证 required_fields = ["from", "to", "amount"] for field in required_fields: if field not in transaction: raise ValueError(f"交易缺少必要字段: {field}") if transaction["amount"] <= 0: raise ValueError("交易金额必须大于0") # 添加时间戳和唯一ID transaction["timestamp"] = time.time() transaction["id"] = str(uuid4()) self.pending_transactions.append(transaction) 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["from"] == address: balance -= transaction["amount"] if transaction["to"] == address: balance += transaction["amount"] return balance def is_chain_valid(self) -> bool: """验证区块链的完整性""" for i in range(1, len(self.chain)): current_block = self.chain[i] previous_block = self.chain[i-1] # 检查当前区块的哈希是否正确 if current_block.hash != current_block.calculate_hash(): print(f"区块 {current_block.index} 的哈希值无效") return False # 检查区块是否链接正确 if current_block.previous_hash != previous_block.hash: print(f"区块 {current_block.index} 的前置哈希值无效") return False # 检查工作量证明 if current_block.hash[:self.difficulty] != "0" * self.difficulty: print(f"区块 {current_block.index} 的工作量证明无效") return False return True def display_chain(self) -> None: """显示区块链的所有区块""" print("\n" + "="*60) print("区块链信息") print("="*60) for block in self.chain: print(f"\n区块 #{block.index}") print(f" 哈希: {block.hash}") print(f" 前置哈希: {block.previous_hash}") print(f" 时间戳: {datetime.fromtimestamp(block.timestamp).strftime('%Y-%m-%d %H:%M:%S')}") print(f" Nonce: {block.nonce}") print(f" 交易数量: {len(block.transactions)}") if block.transactions: print(" 交易详情:") for tx in block.transactions: if tx["from"] == "network": print(f" 🪙 挖矿奖励: {tx['amount']} -> {tx['to']}") else: print(f" 💰 转账: {tx['from'][:8]}... -> {tx['to'][:8]}...: {tx['amount']}") print("\n" + "="*60) print(f"区块链长度: {len(self.chain)}") print(f"区块链有效: {self.is_chain_valid()}") print("="*60) 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 # 创建一些测试地址 alice_address = "Alice_Wallet_Address_123" bob_address = "Bob_Wallet_Address_456" charlie_address = "Charlie_Wallet_Address_789" print(f"\n初始余额:") print(f" Alice: {blockchain.get_balance(alice_address)}") print(f" Bob: {blockchain.get_balance(bob_address)}") print(f" Charlie: {blockchain.get_balance(charlie_address)}") # 添加一些交易 print("\n添加交易...") blockchain.add_transaction({ "from": alice_address, "to": bob_address, "amount": 5.0 }) blockchain.add_transaction({ "from": bob_address, "to": charlie_address, "amount": 2.5 }) # Alice挖矿 print(f"\nAlice开始挖矿...") blockchain.mine_pending_transactions(alice_address) # 添加更多交易 blockchain.add_transaction({ "from": charlie_address, "to": alice_address, "amount": 1.0 }) # Bob挖矿 print(f"\nBob开始挖矿...") blockchain.mine_pending_transactions(bob_address) # 显示区块链 blockchain.display_chain() print(f"\n最终余额:") print(f" Alice: {blockchain.get_balance(alice_address)}") print(f" Bob: {blockchain.get_balance(bob_address)}") print(f" Charlie: {blockchain.get_balance(charlie_address)}") # 演示区块链篡改检测 print("\n" + "="*60) print("演示区块链篡改检测...") print("="*60) # 尝试篡改区块链 if len(blockchain.chain) > 1: print(f"\n尝试篡改区块 #{blockchain.chain[1].index} 的交易...") original_hash = blockchain.chain[1].hash blockchain.chain[1].transactions[0]["amount"] = 100

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