python区块链简单模拟【03】

引入钱包，账户地址，公私钥

# 导入椭圆曲线算法
from ecdsa import SigningKey, SECP256k1, VerifyingKey, BadSignatureError
import binascii
import base64
from hashlib import sha256


class Wallet:
    """
        钱包
    """
    def __init__(self):
        """
            钱包初始化时基于椭圆曲线生成一个唯一的秘钥对，代表区块链上一个唯一的账户
        """
        self._private_key = SigningKey.generate(curve=SECP256k1)   #私钥  签名
        self._public_key = self._private_key.get_verifying_key()   #公钥  验证 

    @property    #通过 @property 装饰器，可以直接通过方法名来访问方法，不需要在方法名后添加一对"（）"小括号。
    def address(self):
        """
            这里通过公钥生成地址
            base64.b64encode()将bytes类型数据进行base64编码，返回编码后的bytes类型
            base64.b64deocde()将base64编码的bytes类型进行解码，返回解码后的bytes类型、
            常见于网址url加密中
        """
        h = sha256(self._public_key.to_pem())
        return base64.b64encode(h.digest())  #返回16进制sha256哈希加密后的哈希值并对其进行编码

    @property
    def pubkey(self):
        """
            返回公钥字符串
        """
        return self._public_key.to_pem()

    def sign(self, message):
        """
            生成数字签名
        """
        h = sha256(message.encode('utf8'))
        return binascii.hexlify(self._private_key.sign(h.digest()))  #二进制输出

    
def verify_sign(pubkey, message, signature):
    """
        验证签名
    """
    verifier = VerifyingKey.from_pem(pubkey)
    h = sha256(message.encode('utf8'))
    return verifier.verify(binascii.unhexlify(signature), h.digest())

# 新建一个钱包

w = Wallet()

# 打印钱包地址  
w.address

# 打印钱包公钥

w.pubkey

# 测试数据

data = "交易数据"

# 生成签名

sig = w.sign(data)

# 打印签名
print(sig)

# 验证签名

verify_sign(w.pubkey, data, sig)

import json

class Transaction:
    """
    交易的结构
    """
    def __init__(self, sender, recipient, amount):
        """
            初始化交易，设置交易的发送方、接收方和交易数量
        """
        if isinstance(sender, bytes):
            sender = sender.decode('utf-8')
        self.sender = sender            # 发送方
        if isinstance(recipient, bytes):
            recipient = recipient.decode('utf-8')
        self.recipient = recipient      # 接收方
        self.amount = amount            # 交易数量
        
    def set_sign(self, signature, pubkey):
        """
            为了便于验证这个交易的可靠性，需要发送方输入他的公钥和签名
        """
        self.signature = signature      # 签名
        self.pubkey = pubkey            # 发送方公钥  提供给验证者和接收方用来验证交易
        
    def __repr__(self):
        """
            交易大致可分为两种，一是挖矿所得，而是转账交易
            挖矿所得无发送方，以此进行区分显示不同内容
        """
        if self.sender:           #发送方不为空，则是转账交易   
            s = "从 %s 转至 %s %d个加密货币" % (self.sender, self.recipient, self.amount)
        else:                     #否则是挖矿所得
            s = "%s 挖矿获取%d个加密货币" % (self.recipient, self.amount)
        return s


class TransactionEncoder(json.JSONEncoder):
    """
    定义Json的编码类，用来序列化Transaction
    """
    def default(self, obj):
        if isinstance(obj, Transaction):
            return obj.__dict__
        else:
            return json.JSONEncoder.default(self, obj)

`import hashlib

from datetime import datetime

class Block:

"""

区块结构

prev_hash: 父区块哈希值

transactions: 交易列表

timestamp: 区块创建时间

hash: 区块哈希值

Nonce: 随机数

"""

def init (self, transactions, prev_hash):

将传入的父哈希值和数据保存到类变量中

self.prev_hash = prev_hash

self.transactions = transactions

获取当前时间

self.timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")

    # 设置Nonce和哈希的初始值为None
    self.nonce = None
    self.hash = None
    
def __repr__(self):
    return "区块内容：%s\n哈希值: %s" % (json.dumps(self.transactions), self.hash)`

class ProofOfWork:
    """
        工作量证明
        简化为一个挖矿者，只要挖矿就一定能挖到，只是时间问题
    """
    def __init__(self, block, miner, difficult=5):
        self.block = block
        
        # 定义工作量难度，默认为5，表示有效的哈希值以5个"0"开头
        self.difficulty = difficult

        self.miner = miner
        
        # 添加挖矿奖励
        self.reward_amount = 1  #奖励一个加密货币

    def mine(self):
        """
            挖矿函数
        """
        i = 0                            #初始化随机值
        prefix = '0' * self.difficulty   #设置难度
        
        
        # 添加奖励                    新建挖矿交易
        t = Transaction(
                sender="",
                recipient=self.miner.address,
                amount=self.reward_amount,
            )
        sig = self.miner.sign(json.dumps(t, cls=TransactionEncoder))    #钱包类中的账户使私钥签名
        t.set_sign(sig, self.miner.pubkey)                              #发送签名和公钥
        self.block.transactions.append(t)                               #将交易添加到区块链中交易列表中

        while True:
            message = hashlib.sha256()
            message.update(str(self.block.prev_hash).encode('utf-8'))
            # 更新区块中的交易数据
            # message.update(str(self.block.data).encode('utf-8'))
            message.update(str(self.block.transactions).encode('utf-8'))
            message.update(str(self.block.timestamp).encode('utf-8'))
            message.update(str(i).encode("utf-8"))
            digest = message.hexdigest()
            if digest.startswith(prefix):
                self.block.nonce = i
                self.block.hash = digest
                return self.block
            i += 1

    def validate(self):
        """
            验证有效性
        """
        message = hashlib.sha256()
        
        #四句话将区块各个参数进行哈希运算
        message.update(str(self.block.prev_hash).encode('utf-8'))
        # 更新区块中的交易数据
        # message.update(str(self.block.data).encode('utf-8'))
        message.update(json.dumps(self.block.transactions).encode('utf-8'))
        message.update(str(self.block.timestamp).encode('utf-8'))
        message.update(str(self.block.nonce).encode('utf-8'))
        
        digest = message.hexdigest()  #16进制输出hash值

        prefix = '0' * self.difficulty
        return digest.startswith(prefix)   #验证是否为符合难度的哈希值

class BlockChain:
    """
        区块链结构体
            blocks:        包含的区块列表
    """
    def __init__(self):
        self.blocks = []

    def add_block(self, block):
        """
        添加区块
        """
        self.blocks.append(block)
    
    def print_list(self):
        print("区块链包含区块个数: %d\n" % len(self.blocks))
        for block in self.blocks:
            print("上个区块哈希：%s" % block.prev_hash)
            print("区块内容：%s" % block.transactions)
            print("区块哈希：%s" % block.hash)
            print("\n") 

def get_balance(user):
    balance = 0
    for block in blockchain.blocks:
        for t in block.transactions:
            if t.sender == user.address.decode():
                balance -= t.amount
            elif t.recipient == user.address.decode():
                balance += t.amount
    return balance

# 初始化区块链
blockchain = BlockChain()

# 创建三个钱包，一个属于alice，一个属于tom，剩下一个属于bob
alice = Wallet()
tom = Wallet()
bob = Wallet()

# 打印当前钱包情况
print("alice: %d个加密货币" % (get_balance(alice)))
print("tom: %d个加密货币" % (get_balance(tom)))
print("bob: %d个加密货币" % (get_balance(bob)))

# alice生成创世区块，并添加到区块链中

new_block1 = Block(transactions=[], prev_hash="")
w1 = ProofOfWork(new_block1, alice)
genesis_block = w1.mine()
blockchain.add_block(genesis_block)

# 显示alice当前余额

print("alice: %d个加密货币" % (get_balance(alice)))

# alice 转账给 tom 0.3个加密货币
transactions = []
new_transaction = Transaction(
    sender=alice.address,
    recipient=tom.address,
    amount=0.3
)
sig = tom.sign(str(new_transaction))       #私钥签名
new_transaction.set_sign(sig, tom.pubkey)  #发送签名和公钥

# bob 在网络上接收到这笔交易，进行验证没问题后生成一个新的区块并添加到区块链中

if verify_sign(new_transaction.pubkey, 
                  str(new_transaction),
                   new_transaction.signature):    #验证者验证
    
    # 验证交易签名没问题，生成一个新的区块
    print("验证交易成功")
    new_block2 = Block(transactions=[new_transaction], prev_hash="")
    print("生成新的区块...")
    w2 = ProofOfWork(new_block2, bob)
    block = w2.mine()                              #bob挖矿，找到新的区块将其写入区块链
    print("将新区块添加到区块链中")
    blockchain.add_block(block)
else:
    print("交易验证失败！")

# 打印当前钱包情况 print("alice: %.1f个加密货币" % (get_balance(alice))) print("tom: %.1f个加密货币" % (get_balance(tom))) print("bob: %d个加密货币" % (get_balance(bob)))