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Watashi

# 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 import time from typing import List, Dict, Any class Block: """区块类""" def __init__(self, index: int, timestamp: float, transactions: List[Dict], previous_hash: str, nonce: int = 0): self.index = index self.timestamp = timestamp self.transactions = transactions 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, "timestamp": self.timestamp, "transactions": self.transactions, "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}, " f"timestamp={self.timestamp}, " f"transactions={len(self.transactions)}, " f"previous_hash={self.previous_hash[:10]}..., " f"hash={self.hash[:10]}..., " f"nonce={self.nonce})") class Blockchain: """区块链类""" def __init__(self, difficulty: int = 4): self.chain: List[Block] = [] self.difficulty = difficulty # 工作量证明难度 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, 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), timestamp=time.time(), transactions=self.pending_transactions, previous_hash=self.get_latest_block().hash ) # 执行工作量证明 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} 挖矿完成，nonce: {block.nonce}") 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}") 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(f"区块数量: {len(self.chain)}") print(f"难度: {self.difficulty}") print(f"挖矿奖励: {self.mining_reward}") print(f"区块链有效: {self.is_chain_valid()}") print("="*60) for block in self.chain: print(f"\n区块 #{block.index}:") print(f" 时间戳: {time.ctime(block.timestamp)}") print(f" 上一个哈希: {block.previous_hash[:20]}...") print(f" 当前哈希: {block.hash[:20]}...") print(f" Nonce: {block.nonce}") print(f" 交易数量: {len(block.transactions)}") for i, transaction in enumerate(block.transactions): print(f" 交易 {i+1}: {transaction['from']} -> {transaction['to']}: {transaction['amount']}") # 示例使用 def main(): # 创建区块链 print("创建区块链...") my_blockchain = Blockchain(difficulty=3) # 添加一些交易 print("\n添加交易...") my_blockchain.add_transaction({"from": "Alice", "to": "Bob", "amount": 5.0}) my_blockchain.add_transaction({"from": "Bob", "to": "Charlie", "amount": 2.5}) # 挖矿（打包交易到区块） print("\n开始挖矿...") my_blockchain.mine_pending_transactions("Miner1") # 添加更多交易 print("\n添加更多交易...") my_blockchain.add_transaction({"from": "Charlie", "to": "Alice", "amount": 1.0}) my_blockchain.add_transaction({"from": "Alice", "to": "David", "amount": 3.0}) # 再次挖矿 print("\n开始第二次挖矿...") my_blockchain.mine_pending_transactions("Miner2") # 显示区块链 my_blockchain.display_chain() # 显示余额 print("\n账户余额:") for address in ["Alice", "Bob", "Charlie", "David", "Miner1", "Miner2"]: balance = my_blockchain.get_balance(address) print(f" {address}: {balance}") # 验证区块链 print(f"\n区块链是否有效 # 尝试篡改区块链（演示验证失败） print("\n尝试篡改区块链...") if len(my_blockchain.chain) > 1: my_blockchain.chain[1].transactions[0]["amount"] = 100.0 # 篡改交易 print(f"篡改后区块链是否有效 if __name__ == "__main__": main() ``` ## 代码说明这个简单的区块链实现包含以下核心功能： ### 1. **区块结构 (Block类)** - 包含索引、时间戳、交易列表、前一个区块的哈希、随机数(nonce)和当前哈希 - 使用SHA-256算法计算哈希值 ### 2. **区块链 (Blockchain类)** - 维护一个区块列表（链） - 实现工作量证明机制 - 管理待处理交易 ### 3. **核心功能** - **创世区块创建**：区块链的第一个区块 - **工作量证明**：通过计算找到满足特定条件的哈希值（前导零的数量由难度决定） - **交易添加**：将交易添加到待处理交易池

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