Python实现简单的区块链，实现共识算法、Merkle Tree（默克尔树）、冲突解决、添加交易等功能

Python实现简单的区块链

记录自己假期所学相关内容
文章中的内容，开源代码地址见文末。

1、分模块实现简单的单节点区块链

1.1 Transaction类

class Transaction:def __init__(self,payer,  # 付款方r ecer,  # 收款方money):  # 数字货币的数额self.payer = payerself.recer = recerself.money = moneyself.timestamp = datetime.datetime.now()  # 交易时间def __repr__(self):return str(self.payer) + " pays " + str(self.recer) + \" " + str(self.money) + " " + str(self.timestamp)

1.2 DaDaMessage类

class DaDaMessage:  # 交易记录类def __init__(self, data):self.hash = None  # 自身的哈希self.prev_hash = None  # 上一个信息记录的哈希self.timestamp = datetime.datetime.now()  # 交易时间self.data = data  # 交易信息self.payload_hash = self._hash_payload()  # 交易后的哈希def _hash_payload(self):  # 对于交易时间与交易数据进行哈希计算return hashlib.sha256((str(self.timestamp) + str(self.data)).encode()).hexdigest()def _hash_message(self):  # 对于交易进行锁定return hashlib.sha256((str(self.prev_hash) + str(self.payload_hash)).encode()).hexdigest()def seal(self):  # 密封self.hash = self._hash_message()  # 对应数据锁定，对于交易前的链锁定def validate(self):  # 验证if self.payload_hash != self._hash_payload():  # 判断是否有人修改raise InvalidMessage("交易数据与时间被修改" + str(self))if self.hash != self._hash_message():  # 判断消息链raise InvalidMessage("交易的哈希链接被修改" + str(self))return "数据正常" + str(self)def __repr__(self):  # 返回对象的基本信息mystr = "hash:{}, prev_hash:{}, data:{}".format(self.hash, self.prev_hash, self.data)return mystrdef link(self, Message):self.prev_hash = Message.hash  # 链接

1.3 Block类

class Block:def __init__(self, *args):  # 初始化self.messageList = []  # 存储多个交易记录，存放区块self.timestamp = None  # 存储多个记录最终锁定的时间self.hash = None  # 当前的哈希散列self.prev_hash = None  # 上一块的哈希散列if args:for arg in args:self.add_message(arg)# self.messagelist.append(arg)def add_message(self, message):  # 增加交易信息# 区分第一条与后面多条，是否需要链接if len(self.messageList) > 0:message.link(self.messageList[-1])  # 链接message.seal()  # 密封message.validate()  # 校验self.messageList.append(message)  # 追加记录def link(self, block):  # 区块链链接self.prev_hash = block.hashdef seal(self):  # 密封self.timestamp = datetime.datetime.now()  # 密封确定当前时间self.hash = self._hash_block()  # 密封当前的哈希值def _hash_block(self):  # 密封 上一块哈希，时间线，交易记录的最后一个if len(self.messageList) > 0:return hashlib.md5((str(self.prev_hash) +str(self.timestamp) +str(self.messageList[-1].hash)).encode("utf-8")).hexdigest()# else:#     return hashlib.sha256((str(self.prev_hash) +#                            str(self.timestamp) +#                            str(0)).encode("utf-8")).hexdigest()def validate(self):  # 校验for i, message in enumerate(self.messageList):  # 校验每一个交易记录message.validate()  # 校验每一条if i > 0 and message.prev_hash != self.messageList[i - 1].hash:raise InvalidBlock("无效block，交易记录被修改为在第{}条记录".format(i) + str(self))#         print("无效block，交易记录被修改为在第{}条记录".format(i))#         return str(self) + "数据NO"return "   " + str(self) + "  数据OK"def __repr__(self):  # 类的对象描述# return "money block = hash : {}, pre_hash : {}, len : {}, time : {}".\#     format(self.hash, self.prev_hash, len(self.messageList), self.timestamp)return "money block \n hash : {} \n pre_hash : {} \n len : {} \n time : {}". \format(self.hash, self.prev_hash, len(self.messageList), self.timestamp)

1.4 Dada_BlockCoin类

class Dada_BlockCoin:  # 区块链def __init__(self):  # 初始化self.blockList = []def add_block(self, block):  # 增加区块if (len(self.blockList) > 0):block.prev_hash = self.blockList[-1].hash  # 区块链的哈希block.seal()  # 密封block.validate()  # 校验self.blockList.append(block)  # 增加区块def validate(self):  # 校验for i, block in enumerate(self.blockList):try:block.validate()except InvalidBlock as e:raise InvalidBlockCoin("区块校验错误，区块索引{}".format(i))except InvalidMessage as e:print(e)def __repr__(self):  # 字符串格式化return "Dada_BlockCoin : {}".format(len(self.blockList))  # 获取长度

1.5 主函数BlockChainApp类

class BlockChainApp:def __init__(self, root):self.root = rootself.root.title("区块链可视化")self.blockchain = Dada_BlockCoin()self.current_block_transactions = []self.selected_block_index = None# 添加滚动条self.canvas_frame = tk.Frame(root)self.canvas_frame.pack(expand=tk.YES, fill=tk.BOTH)self.scrollbar_x = tk.Scrollbar(self.canvas_frame, orient=tk.HORIZONTAL)self.scrollbar_x.pack(side=tk.BOTTOM, fill=tk.X)self.scrollbar_y = tk.Scrollbar(self.canvas_frame)self.scrollbar_y.pack(side=tk.RIGHT, fill=tk.Y)# 区块链信息显示框self.canvas = tk.Canvas(self.canvas_frame, width=800, yscrollcommand=self.scrollbar_y.set,xscrollcommand=self.scrollbar_x.set)self.canvas.pack(side=tk.LEFT, expand=tk.YES, fill=tk.BOTH)self.scrollbar_x.config(command=self.canvas.xview)self.scrollbar_y.config(command=self.canvas.yview)self.canvas.config(scrollregion=self.canvas.bbox(tk.ALL))# 交易信息输入框self.payer_label = tk.Label(root, text="付款方:")self.payer_label.pack()self.payer_entry = tk.Entry(root)self.payer_entry.pack()self.recer_label = tk.Label(root, text="收款方:")self.recer_label.pack()self.recer_entry = tk.Entry(root)self.recer_entry.pack()self.money_label = tk.Label(root, text="金额:")self.money_label.pack()self.money_entry = tk.Entry(root)self.money_entry.pack()# 添加交易按钮self.add_transaction_btn = tk.Button(root, text="添加交易", command=self.add_transaction)self.add_transaction_btn.pack()# 添加区块按钮self.add_block_btn = tk.Button(root, text="添加区块", command=self.add_block)self.add_block_btn.pack()# 模拟篡改按钮self.tamper_block_btn = tk.Button(root, text="模拟篡改数据", command=self.tamper_block)self.tamper_block_btn.pack()# 区块查询框self.query_frame = tk.Frame(root)self.query_frame.pack()self.query_label = tk.Label(self.query_frame, text="查询区块索引:")self.query_label.pack(side=tk.LEFT)self.query_entry = tk.Entry(self.query_frame)self.query_entry.pack(side=tk.LEFT)self.query_btn = tk.Button(self.query_frame, text="查询区块", command=self.query_block)self.query_btn.pack(side=tk.LEFT)# 交易信息显示框self.transaction_info_text = tk.Text(root, wrap=tk.WORD, width=60, height=10)self.transaction_info_text.pack()def add_transaction(self):payer = self.payer_entry.get()recer = self.recer_entry.get()money = self.money_entry.get()try:money = int(money)except ValueError:messagebox.showerror("错误", "金额必须为整数")returnif payer and recer and money > 0:transaction = Transaction(payer, recer, money)self.current_block_transactions.append(DaDaMessage(transaction))self.update_blockchain_info()messagebox.showinfo("成功", "交易添加成功")else:messagebox.showerror("错误", "请输入有效的交易信息")def add_block(self):if self.current_block_transactions:block = Block(*self.current_block_transactions)self.blockchain.add_block(block)self.current_block_transactions = []self.update_blockchain_info()messagebox.showinfo("成功", "区块添加成功")else:messagebox.showerror("错误", "当前区块没有交易信息")def tamper_block(self):try:block_index = int(input("请输入要篡改的区块索引："))except ValueError:messagebox.showerror("错误", "请输入有效的区块索引")returnif 0 <= block_index < len(self.blockchain.blockList):block = self.blockchain.blockList[block_index]if len(block.messageList) > 0:# 模拟篡改第一条交易信息block.messageList[0].data = "篡改后的交易信息"try:self.blockchain.validate()except InvalidBlockCoin as e:messagebox.showerror("篡改数据", "区块链数据已被篡改，篡改发生在第{}个区块".format(e.args[0]))except InvalidMessage as e:messagebox.showerror("篡改数据", "区块链数据已被篡改，篡改发生在第{}个区块的第{}条交易信息".format(e.args[0][0], e.args[0][1]))else:messagebox.showinfo("篡改数据", "区块链数据未被篡改")finally:self.update_blockchain_info()else:messagebox.showerror("错误", "区块中没有交易信息，无法篡改")else:messagebox.showerror("错误", "区块索引超出范围")def query_block(self):try:block_index = int(self.query_entry.get())except ValueError:messagebox.showerror("错误", "请输入有效的区块索引")returnif 0 <= block_index < len(self.blockchain.blockList):block = self.blockchain.blockList[block_index]transactions = "\n".join(str(msg.data) for msg in block.messageList)self.transaction_info_text.delete("1.0", tk.END)self.transaction_info_text.insert(tk.END, transactions)self.selected_block_index = block_indexmessagebox.showinfo("成功", "查询成功")else:messagebox.showerror("错误", "区块索引超出范围")def update_blockchain_info(self):self.canvas.delete("all")  # 清空画布上的内容x, y = 20, 50  # 区块链的初始位置block_width, block_height = 250, 150  # 区块的宽度和高度for block in self.blockchain.blockList:self.canvas.create_rectangle(x, y, x + block_width, y + block_height, outline="black")  # 绘制区块框self.canvas.create_text(x + block_width // 2, y + block_height // 2, text=str(block))  # 显示区块信息if block.prev_hash:  # 绘制区块之间的连接线prev_x, prev_y = x - block_width, y + block_height // 2self.canvas.create_line(prev_x, prev_y, x, y + block_height // 2, fill="red")x += block_width + 50  # 每个区块之间留一定的间隔# 设置Canvas可滚动范围self.canvas.config(scrollregion=self.canvas.bbox(tk.ALL))if __name__ == "__main__":root = tk.Tk()app = BlockChainApp(root)app.root.mainloop()

1.6 主函数类中实现了可视化界面，以下为演示效果

• 初始化界面

• 添加交易后添加区块
  

在上述区块链可视化界面中显示对应区块，并用红色连线连接，表示区块链的哈希连接。

• 查询区块信息
  
  输入区块对应的索引（从0开始），即可查询对应区块的交易信息

2、网络共识区块链编程实现

2.1 DaDaCoinBlockChain类

class DaDaCoinBlockChain:def __init__(self):  # 初始化self.current_transactions = []  # 交易列表self.chain = []  # 区块链管理多个区块self.nodes = set()  # 保存网络中其他节点self.new_block(previous_hash="1", proof=100)  # 创建创世区块def new_block(self,proof: int,  # 确定proof为int类型previous_hash: Optional[str]  # 上一块的哈希类型) -> Dict[str, Any]:  # 创建一个区块，返回一个字典数据类型block = {"index": len(self.chain) + 1,  # 索引"timestamp": time.time(),  # 当前时间"transaction": self.current_transactions,  # 交易记录"proof": proof,  # 工作量证明"previous_hash": previous_hash or self.hash(self.chain[-1])  # 前一区块哈希}self.current_transactions = []  # 交易记录加入区块之后清空self.chain.append(block)  # 区块加入区块链return blockdef new_transactions(self, sender: str, recipient: str, amount) -> int:  # 创建一个交易self.current_transactions.append({"sender": sender,  # 付款方"recipient": recipient,  # 收款方"amount": amount  # 数量})return self.last_block["index"] + 1  # 索引标记交易数量@propertydef last_block(self) -> Dict[str, Any]:  # 取得最后一个区块return self.chain[-1]@staticmethoddef hash(block: Dict[str, any]) -> str:  # 哈希加密，传递一个字典，返回字符串blockString = json.dumps(block, sort_keys=True).encode()  # 编码return hashlib.sha256(blockString).hexdigest()def proof_of_work(self, last_proof: int) -> int:  # 工作量证明，挖矿过程proof = 0while self.valid_proof(last_proof, proof) is False:proof += 1return proof@staticmethod  # 第N个区块依赖于N-1个区块，简单挖矿def valid_proof(last_proof: int, proof: int) -> bool:  # 验证证明guess = f'{last_proof * proof}'.encode()guess_hash = hashlib.sha256(guess).hexdigest()# print(str(guess_hash))return guess_hash[-4:] == "1234"def valid_chain(self, chain: List[Dict[str, Any]]) -> bool:  # 区块链校验# List[Dict[str, Any]]是一个列表，列表的每个元素都是字典last_block = chain[0]  # 第一个区块curr_index = 1  # 当前的第一个索引while curr_index < len(chain):block = chain[curr_index]  # 当前区块# 哈希校验，校验区块链的链接if block["previous_hash"] != self.hash(last_block):return False# 工作量校验，挖矿的工作量校验if not self.valid_proof(last_block["proof"], block["proof"]):return Falselast_block = block  # 轮询curr_index += 1  # 索引自增return Truedef register_node(self, addr: str) -> None:  # 加入网络的其他节点，用于更新now_url = urlparse(addr)  # 解析self.nodes.add(now_url.netloc)  # 增加网络节点def resolve_conflicts(self) -> bool:  # 共识算法# 网络中的多个节点，取出最长的neighbours = self.nodes  # 取得所有的节点new_chain = None  # 新的区块链max_length = len(self.chain)  # 当前的区块链长度for node in neighbours:response = requests.get(f"http://{node}/chain")  # 访问网络节点if response.status_code == 200:length = response.json()["length"]  # 取出长度chain = response.json()["chain"]  # 取出区块链# 如果当前区块链比我长并且经得起校验，那么就更新if length > max_length and self.valid_chain(chain):max_length = lengthnew_chain = chain  # 保存长度与区块链if new_chain:self.chain = new_chain  # 替换区块链return Truereturn False

2.2 flask框架部分

dadacoin = DaDaCoinBlockChain()  # 创建一个网络节点
node_id = str(uuid4()).replace("-", "")  # 节点替换，生成密钥
print("当前钱包地址：", node_id)
app = Flask(__name__)  # 初始化flask框架@app.route("/")
def index_page():return "你好，欢迎来到达达币系统！"@app.route("/chain")  # 查看所有的区块链
def index_chain():response = {"chain": dadacoin.chain,  # 区块链"length": len(dadacoin.chain)  # 区块链长度}return jsonify(response), 200@app.route("/mine")  # 挖矿
def index_mine():last_block = dadacoin.last_block  # 取得最后一个区块last_proof = last_block["proof"]  # 取得工作量证明proof = dadacoin.proof_of_work(last_proof)  # 挖矿计算# 系统奖励比特币，挖矿产生交易dadacoin.new_transactions(sender="0",  # 0代表系统奖励recipient=node_id,  # 当前钱包地址amount=10  # 奖励数量)block = dadacoin.new_block(proof, None)  # 增加一个区块response = {"message": "新的区块创建","index": block["index"],  # 仓建的索引"transaction": block["transaction"],  # 交易"proof": block["proof"],  # 工作量证明"previous_hash": block["previous_hash"]  # 上一块的哈希}return jsonify(response), 200@app.route("/new_transaction", methods=["POST"])  # 创建一个新的交易
def new_transaction():values = request.get_json()  # 抓取网络传输的信息required = ["sender", "recipient", "amount"]if not all(key in values for key in required):return "数据不完整", 400index = dadacoin.new_transactions(values["sender"],values["recipient"],values["amount"])  # 新增一个交易response = {"message": f"交易加入到区块{index}",}return jsonify(response), 200@app.route("/new_node", methods=["POST"])   # 增加网络节点
def new_node():values = request.get_json() # 获取json字符串nodes = values.get("nodes") # 获取所有节点if nodes is None:return "节点为空", 400for node in nodes:dadacoin.register_node(node)    # 增加网络节点response = {"message": "网络节点已经增加","nodes": list(dadacoin.nodes)   # 查看所有节点}return jsonify(response), 200@app.route("/node_refresh")
def node_refresh():replaced = dadacoin.resolve_conflicts() # 共识算法进行最长替换message = ""if replaced:message += "区块链已经被替换为最长"else:message += "当前区块链已经是最长无需替换"response = {"message": message,"new--chain": dadacoin.chain}return jsonify(response), 200

2.3 初始化三个节点，分别模拟网络中的三个矿工

if __name__ == '__main__':app.run("127.0.0.1", 5000)if __name__ == '__main__':app.run("127.0.0.1", 5001)if __name__ == '__main__':app.run("127.0.0.1", 5002)

2.4 效果演示

分别启动三个矿工节点

• 初始化界面
  
• 初次访问chain路径时，显示创世区块
  
• 访问mine路径时，进行挖矿操作，挖出新的区块，矿工获得出块奖励
  
• 添加交易
  使用postman进行操作
  
  此时仅仅是将交易添加到区块，还没有挖出区块3，再次进行mine操作，可以看到区块3中除了出块奖励，还有此次交易
  
• 网络共识，解决分叉冲突
  此时模拟节点1挖出6个区块，节点2挖出4个区块，节点3挖出3个区块。将节点1和节点2的信息同步给区块3，此时根据最长链原则，应该更新为节点1的6个区块。
  使用postman添加节点
  
  刷新节点信息
  
  此时节点3已经被最长链代替。

3、其他

开源代码地址： Gitee仓库
b站参考视频：参考视频