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Blistex

# 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，包含基本的区块链结构、工作量证明（PoW）和交易功能。```pythonimport hashlibimport jsonfrom time import timefrom typing import List, Dict, Anyimport uuidclass 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.current_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.create_genesis_block() def create_genesis_block(self): """创建创世区块""" genesis_block = Block(0, [], time(), "0") self.chain.append(genesis_block) def get_last_block(self) -> Block: """获取链上最后一个区块""" return self.chain[-1] def add_transaction(self, sender: str, recipient: str, amount: float) -> int: """添加新交易到当前交易列表""" self.current_transactions.append({ "sender": sender, "recipient": recipient, "amount": amount, "id": str(uuid.uuid4())[:8] }) return self.get_last_block().index + 1 def proof_of_work(self, block: Block) -> int: """工作量证明算法""" block.nonce = 0 computed_hash = block.calculate_hash() while not computed_hash.startswith('0' * self.difficulty): block.nonce += 1 computed_hash = block.calculate_hash() return block.nonce def mine_block(self, miner_address: str) -> Block: """挖矿生成新区块""" # 添加矿工奖励交易 self.add_transaction( sender="0", # 系统奖励 recipient=miner_address, amount=1.0 # 挖矿奖励 ) last_block = self.get_last_block() # 创建新区块 new_block = Block( index=last_block.index + 1, transactions=self.current_transactions, timestamp=time(), previous_hash=last_block.hash ) # 执行工作量证明 self.proof_of_work(new_block) # 将新区块添加到链上 self.chain.append(new_block) # 重置当前交易列表 self.current_transactions = [] return new_block 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值是否正确 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 # 验证工作量证明 if not current_block.hash.startswith('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["sender"] == address: balance -= transaction["amount"] if transaction["recipient"] == address: balance += transaction["amount"] return balance def display_chain(self): """显示整个区块链""" print("\n" + "="*60) print("区块链信息") print("="*60) print(f"链长度: {len(self.chain)}") print(f"当前待处理交易数: {len(self.current_transactions)}") print(f"挖矿难度: {self.difficulty}") print("-"*60) for block in self.chain: print(f"\n区块 #{block.index}:") print(f" 哈希: {block.hash[:20]}...") print(f" 前置哈希: {block.previous_hash[:20]}...") print(f" 时间戳: {block.timestamp}") print(f" 随机数: {block.nonce}") print(f" 交易数: {len(block.transactions)}") if block.transactions: print(" 交易详情:") for tx in block.transactions: print(f" {tx['sender'][:8]} -> {tx['recipient'][:8]}: {tx['amount']} (ID: {tx['id']})") print("\n" + "="*60)def main(): """主函数演示区块链功能""" # 创建区块链 blockchain = Blockchain() print("初始化区块链...") # 添加一些交易 print("\n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) # 挖矿生成新区块 print("\n开始挖矿...") new_block = blockchain.mine_block("Miner1") print(f"新区块已生成: #{new_block.index}") # 添加更多交易 print("\n添加更多交易...") blockchain.add_transaction("David", "Eve", 3.0) blockchain.add_transaction("Eve", "Frank", 1.5) # 再次挖矿 print("\n开始挖矿...") new_block = blockchain.mine_block("Miner2") print(f"新区块已生成: #{new_block.index}") # 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", "Frank", "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: # 修改第二个区块的第一笔交易 blockchain.chain[1].transactions[0]["amount"] = 100.0 print(f"篡改后区块链是否有效: {blockchain.is_chain_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功能：### 1. **区块结构 (Block类)**- 包含索引(index)、时间戳(timestamp)、交易列表(transactions)、前一个区块的哈希值(previous_hash)、随机数(nonce)和当前区块哈希值(hash)- 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(chain)和当前待处理的交易列表(current_transactions)- 包含创世区块的创建### 3. **工作量证明 (Proof of Work)**- 通过调整nonce值，使区块哈希值以指定数量的0开头- 难度(difficulty)参数控制挖矿难度### 4. **交易系统**- 支持添加交易到待处理交易列表- 挖矿成功时，矿工获得奖励交易### 5. **区块链验证**- 验证每个区块的哈希值是否正确- 验证区块间的链接关系- 验证工作量证明是否满足难度要求### 6. **余额查询**- 通过遍历所有交易计算指定地址的余额## 运行示例运行上述代码，

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