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# 使用Python实现一个简单的区块链下面是一个简单的区块链实现，包含基本的区块结构、工作量证明和链验证功能。 ```python import hashlib import json from time import time from typing import List, Dict, Any 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): self.chain: List[Block] = [] self.pending_transactions: List[Dict] = [] self.difficulty = 4 # 工作量证明难度，表示哈希值前导0的数量 self.mining_reward = 100 # 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(), "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, mining_reward_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": mining_reward_address, "amount": self.mining_reward } self.pending_transactions.append(reward_transaction) # 创建新区块 block = Block( index=len(self.chain), transactions=self.pending_transactions, timestamp=time(), previous_hash=self.get_latest_block().hash ) # 执行工作量证明 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) -> None: """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} 挖矿完成，nonce: {block.nonce}") 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}") self.pending_transactions.append(transaction) print(f"交易已添加: {transaction['from']} -> {transaction['to']} ({transaction['amount']})") 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] # 验证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 # 验证区块是否链接到正确的上一个区块 if current_block.previous_hash != previous_block.hash: print(f"区块 {current_block.index} 的上一个哈希值无效") return False # 验证工作量证明 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 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 display_chain(self) -> None: """显示整个区块链""" 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" 上一个哈希: {block.previous_hash}") print(f" 时间戳: {block.timestamp}") 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: print(f" {tx['from']} -> {tx['to']}: {tx['amount']}") print(f"\n区块链长度: {len(self.chain)}") print(f"区块链是否有效: {self.is_chain_valid()}") print("="*60) def main(): """主函数：演示区块链的基本功能""" # 创建区块链 print("创建新的区块链...") blockchain = Blockchain() # 添加一些交易 print("\n添加交易...") blockchain.add_transaction({"from": "Alice", "to": "Bob", "amount": 50}) blockchain.add_transaction({"from": "Bob", "to": "Charlie", "amount": 25}) # 挖矿（将交易打包成区块） 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({"from": "Charlie", "to": "Alice", "amount": 10}) blockchain.add_transaction({"from": "Dave", "to": "Eve", "amount": 30}) # 再次挖矿 print("\n开始挖矿...") blockchain.mine_pending_transactions("miner2") # 显示区块链 blockchain.display_chain() # 显示余额 print("\n账户余额:") addresses = ["Alice", "Bob", "Charlie", "Dave", "Eve", "miner1", "miner2"] for address in addresses: balance = blockchain.get_balance(address) print(f" {address}: {balance}") # 尝试篡改区块链 print("\n尝试篡改区块链...") if len(blockchain.chain) > 1: blockchain.chain[1].transactions[0]["amount"] = 1000 # 修改交易金额 print(f"区块链是否有效: {blockchain.is_chain_valid()}") # 应该返回False if __name__ == "__main__": main() ``` ## 代码说明 ### 1. 区块结构 (Block类) - `index`: 区块在链中的位置 - `transactions`: 区块包含的交易列表 - `timestamp`: 区块创建时间戳 - `previous_hash`: 前一个区块的哈希值 - `nonce`: 用于工作量证明的随机数 - `hash`: 当前区块的哈希值 ### 2. 区块链功能 (Blockchain类) - **创世区块**: 区块链的第一个区块 - **添加交易**: 将交易添加到待处理交易池 - **挖矿**: 通过工作量证明将待处理交易打包成新区块 - **工作量证明**: 寻找满足特定条件（哈希值以指定数量的0开头）的nonce值 - **链验证**: 检查区块链的完整性和一致性 - **余额查询**: 计算特定地址的余额 ### 3. 主要特点 - 使用SHA-256哈希算法确保数据完整性 - 工作量证明机制防止恶意篡改 - 每个区块包含前一个区块的哈希，形成不可篡改的链 - 简单的交易验证和余额计算 ### 4. 运行示例运行上述代码将： 1. 创建一个新的区块链 2.

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