原文
https://blog.csdn.net/vincent__law/article/details/79606357
版权归原作者所有，如需转载，请联系原作者。
区块链的特点和定义，有很多资料可以查询。但对于程序员，代码对于加深理解有着非常大的作用，以下代码为python实现的一个区块链货币，用来帮助理解。代码中配有注释，copy下来可以直接run，测试代码在最后。
理解前提：理解区块链的“账本”的比喻，基于区块链的电子货币的概念，“挖矿”。
源码同时放到了我的github上。
Github（https://github.com/Warmriver/blockChainHW）
import hashlib
import random
import time
# 区块链中交易
class Transaction:
def __init__(self, from_addr, to_addr, amount):
"""
fromAddr: 交易的发起人的地址
toAdddr: 交易的收款人的地址
amount: 交易金额
"""
self.from_addr = from_addr
self.to_addr = to_addr
self.amount = amount
def __str__(self):
return str(self.from_addr) + " send " + str(self.amount) + " to " + str(self.to_addr)
class Block:
def __init__(self, transactions, timestamp, data = '', previous_hash = '0', nonce = 0):
"""
transactions:交易列表，实际应用时并不能这么传递，因为交易的量很很大
timestamp:时间戳
data:数据
nonce:随机数，使用这个数字的改变来更改block的hash值
previous_hash:上一个模块的hash值
hash:模块的hash值
"""
self.transactions = transactions
self.timestamp = timestamp
self.data = data
self.previous_hash = previous_hash
self.nonce = nonce
self.hash = self.calculate_block_hash()
# 计算hash值，上一个block的hash值也在材料中
def calculate_block_hash(self):
combination = str(self.timestamp) + str(self.data) + str(self.previous_hash) + str(self.nonce)
for trans in self.transactions:
combination += str(trans)
return hashlib.sha256(bytes(combination,'utf-8')).hexdigest()
# 挖掘，为了限制用户节点的挖掘能力，增加proof of work机制，增加挖掘的难度，difficulty越大，hash碰撞越难
def mineblock(self,difficult):
start = 0
while [v for v in self.hash[start:difficult]] != ['0' for v in range(start, difficult)]:
# while [v for v in self.hash[start:difficult]] != ['0' for v in range(start, difficult)]:
self.nonce += 1
self.hash = self.calculate_block_hash()
print("挖到了一个 block，"+self.hash+",difficulty为", difficult)
# 区块链
class BlockChain:
def __init__(self):
"""
diffculty:难度
chain:区块链，这里用数组表示
pending_transactions:等待被挖掘的交易列表
reward_coin:奖励金，对记账用户的奖励，即区块链货币，设置为一个block奖励1.2个，
单一用户修改此项并不会生效，因为每个人都有账本，必须说服多数派，拥有大于百分之50的同意。
"""
self.difficult = 3
self.chain = [self.genesis_block()]
self.pending_transactions = []
self.reward_coin = 1.2
# 创世块
def genesis_block(self):
first_transaction = Transaction("24monkey", "24monkey", 50)
return Block([first_transaction], int(time.time()),"创世模块")
# 获得区块链最新的block
def get_latest_block(self):
return self.chain[len(self.chain) - 1]
# 记录交易
def transaction_record(self, transaction):
self.pending_transactions.append(transaction)
# 对区块链中行为进行交易，mining
def mine_pending_transactions(self, reward_addr):
new_block = Block(self.pending_transactions, int(time.time()), )
new_block.mineblock(self.difficult)
print("成功记录一笔交易，挖到了一个block")
self.chain.append(new_block)
self.pending_transactions = [Transaction('', reward_addr, self.reward_coin)]
# 增加block
def add_block(self, block):
block.previous_hash = self.get_latest_block().hash
block.mineblock(self.difficult)
self.chain.append(block)
# 获得一个账户的balance
def get_balance(self, addr):
balance = 0
for block in self.chain:
for transaction in block.transactions:
if transaction.from_addr == addr:
balance -= transaction.amount
elif transaction.to_addr == addr:
balance += transaction.amount
return balance
# 账本是否本篡改，篡改者需要篡改所有的block且说服他人，篡改很困难
def check_chain_validity(self):
for i in range(1,len(self.chain)):
current_block = self.chain[i]
previous_block = self.chain[i-1]
if(current_block.hash != current_block.calculate_block_hash()):
return False
if(current_block.previous_hash != previous_block.hash):
return False
return True
def time_s():
return int(time.time())
if __name__ == '__main__':
# 初始化一个区块链
vin_coin = BlockChain()
# 两笔交易
trans_a = Transaction("shiki_addr", "vincent_addr", 44)
trans_b = Transaction("vincent_addr", "shiki_addr", 44)
"""
测试挖矿，proof of work的难度测试
"""
vin_coin.add_block(Block([trans_a], time_s(), {" reason " : " I owed you"}))
vin_coin.add_block(Block([trans_b], time_s(), {" reason " : " I gave it back to you cause I love you"}))
"""
测试篡改数据的测试
"""
print("vin币chain合法吗？", vin_coin.check_chain_validity())
vin_coin.chain[1].transactions[0].amount = 40
# 修改一个block后，重新计算这个block的hash，并不能成功
vin_coin.chain[1].hash = vin_coin.chain[1].calculate_block_hash()
print("vin币chain合法吗？", vin_coin.check_chain_validity())
"""
测试vin币奖励机制
"""
vin_coin.transaction_record(trans_a)
vin_coin.transaction_record(trans_b)
vin_coin.mine_pending_transactions("记录者1")
# 由于记录者1获得奖励的事件还没有入账，所以查不到
print("记录者1的账户: ", vin_coin.get_balance("记录者1"))
# 记录者2确认了记录者1的行为，记录者1的账户余额不足
vin_coin.mine_pending_transactions("记录者2")
print("记录者1的账户: ", vin_coin.get_balance("记录者1"))