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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实现的基本区块链示例。这个示例包含了区块链的核心概念：区块结构、哈希计算、工作量证明和链式连接。 ```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, timestamp: float, transactions: List[Dict], proof: int, previous_hash: str): """ 初始化一个新区块 Args: index: 区块在链中的位置 timestamp: 区块创建时间戳 transactions: 区块包含的交易列表 proof: 工作量证明 previous_hash: 前一个区块的哈希值 """ self.index = index self.timestamp = timestamp self.transactions = transactions self.proof = proof self.previous_hash = previous_hash def compute_hash(self) -> str: """ 计算区块的哈希值 Returns: 区块的SHA-256哈希值 """ block_string = json.dumps(self.__dict__, sort_keys=True).encode() return hashlib.sha256(block_string).hexdigest() def __repr__(self) -> str: return f"Block(index={self.index}, timestamp={self.timestamp}, transactions={len(self.transactions)}, proof={self.proof}, previous_hash={self.previous_hash[:10]}...)" class Blockchain: """区块链类""" def __init__(self): """初始化区块链，创建创世区块""" self.chain: List[Block] = [] self.current_transactions: List[Dict] = [] self.create_block(proof=100, previous_hash='1') # 创世区块 def create_block(self, proof: int, previous_hash: str = None) -> Block: """ 创建新区块并添加到链中 Args: proof: 工作量证明 previous_hash: 前一个区块的哈希值 Returns: 新创建的区块 """ if previous_hash is None: previous_hash = self.hash_last_block() block = Block( index=len(self.chain) + 1, timestamp=time(), transactions=self.current_transactions, proof=proof, previous_hash=previous_hash ) # 重置当前交易列表 self.current_transactions = [] # 将区块添加到链中 self.chain.append(block) return block def add_transaction(self, sender: str, recipient: str, amount: float) -> int: """ 添加新交易到待处理交易列表 Args: sender: 发送方地址 recipient: 接收方地址 amount: 交易金额 Returns: 该交易将被添加到的区块索引 """ self.current_transactions.append({ 'sender': sender, 'recipient': recipient, 'amount': amount, 'timestamp': time() }) return self.last_block.index + 1 @property def last_block(self) -> Block: """获取链中的最后一个区块""" return self.chain[-1] def hash_last_block(self) -> str: """计算最后一个区块的哈希值""" return self.last_block.compute_hash() @staticmethod def proof_of_work(last_proof: int) -> int: """ 简单的工作量证明算法：寻找一个数p'，使得hash(pp')以4个0开头，其中p是上一个区块的证明 Args: last_proof: 上一个区块的工作量证明 Returns: 新的工作量证明 """ proof = 0 while not Blockchain.valid_proof(last_proof, proof): proof += 1 return proof @staticmethod def valid_proof(last_proof: int, proof: int) -> bool: """ 验证工作量证明：hash(last_proof, proof)是否以4个0开头 Args: last_proof: 上一个区块的工作量证明 proof: 当前工作量证明 Returns: 验证结果 """ guess = f'{last_proof}{proof}'.encode() guess_hash = hashlib.sha256(guess).hexdigest() return guess_hash[:4] == "0000" def is_chain_valid(self) -> bool: """ 验证区块链是否有效 Returns: 区块链是否有效 """ 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.compute_hash() != current_block.compute_hash(): print(f"区块 {current_block.index} 的哈希值无效") return False # 检查区块是否正确地链接到前一个区块 if current_block.previous_hash != previous_block.compute_hash(): print(f"区块 {current_block.index} 的前一个哈希值无效") return False # 检查工作量证明是否有效 if not self.valid_proof(previous_block.proof, current_block.proof): print(f"区块 {current_block.index} 的工作量证明无效") return False return True def print_chain(self): """打印整个区块链""" print("=" * 60) print("区块链信息:") print(f"链长度: {len(self.chain)}") print("-" * 60) for block in self.chain: print(f"区块 #{block.index}:") print(f" 时间戳: {block.timestamp}") print(f" 交易数: {len(block.transactions)}") print(f" 工作量证明: {block.proof}") print(f" 前一个哈希: {block.previous_hash[:20]}...") print(f" 当前哈希: {block.compute_hash()[:20]}...") if block.transactions: print(" 交易详情:") for tx in block.transactions: print(f" {tx['sender'][:10]}... -> {tx['recipient'][:10]}...: {tx['amount']}") print("-" * 60) # 示例使用 def main(): # 创建区块链 blockchain = Blockchain() print("1. 创建创世区块") blockchain.print_chain() # 添加一些交易 print("\n2. 添加交易") blockchain.add_transaction("Alice", "Bob", 5.0) blockchain.add_transaction("Bob", "Charlie", 2.5) blockchain.add_transaction("Charlie", "Alice", 1.0) print(f"待处理交易数: {len(blockchain.current_transactions)}") # 挖矿（创建新区块） print("\n3. 开始挖矿...") last_block = blockchain.last_block last_proof = last_block.proof proof = blockchain.proof_of_work(last_proof) print(f"找到工作量证明: {proof}") # 创建新区块 previous_hash = blockchain.hash_last_block() block = blockchain.create_block(proof, previous_hash) print(f"新区块已创建: #{block.index}") blockchain.print_chain() # 添加更多交易并创建另一个区块 print("\n4. 添加更多交易并创建另一个区块") blockchain.add_transaction("David", "Eve", 3.0) blockchain.add_transaction("Eve", "Frank", 1.5) print("开始挖矿...") last_proof = blockchain.last_block.proof proof = blockchain.proof_of_work(last_proof) print(f"找到工作量证明: {proof}") block = blockchain.create_block(proof) print(f"新区块已创建: #{block.index}") blockchain.print_chain() # 验证区块链 print("\n5. 验证区块链") is_valid = blockchain.is_chain_valid() print(f"区块链是否有效: {is_valid}") # 尝试篡改区块链 print("\n6. 尝试篡改区块链并验证") if len(blockchain.chain) > 1: # 修改第二个区块的交易 blockchain.chain[1].transactions.append({ 'sender': 'Hacker', 'recipient': 'Hacker', 'amount': 100.0, 'timestamp': time() }) is_valid = blockchain.is_chain_valid() print(f"篡改后区块链是否有效: {is_valid}") if __name__ == "__main__": main() ``` ## 代码说明这个简单的区块链实现包含以下核心组件： 1. **Block类**：表示区块链中的单个区块，包含： - 索引（index） - 时间戳（timestamp） - 交易列表（transactions） - 工作量证明（proof） - 前一个区块的哈希值（previous_hash） 2. **Blockchain类**：管理整个区块链，包含： - 创建创

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