区块链技术在金融领域的应用

    graph TD
    A[密码学基础] --> B[非对称加密]
    A --> C[哈希函数]
    B --> D[公钥加密]
    B --> E[数字签名]
    C --> F[SHA-256]
    C --> G[Merkle树]
    
      
      
      
      
      
      
    
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    graph TD
    A[共识算法] --> B[工作量证明PoW]
    A --> C[权益证明PoS]
    B --> D[哈希计算竞争]
    B --> E[挖矿]
    C --> F[持币权重投票]
    C --> G[权益抵押]
    
      
      
      
      
      
      
    
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    graph TD
    A[分布式账本] --> B[P2P网络]
    A --> C[数据复制]
    B --> D[节点发现]
    B --> E[数据传播]
    C --> F[数据一致性]
    C --> G[容错性]
    
      
      
      
      
      
      
    
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    graph TD
    A[智能合约] --> B[图灵完备]
    A --> C[事件触发]
    B --> D[编程语言]
    B --> E[执行环境]
    C --> F[条件判断]
    C --> G[自动执行]
    
      
      
      
      
      
      
    
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    graph TD
    A[交易发起] --> B[交易签名]
    B --> C[广播交易]
    C --> D[收集交易]
    D --> E[打包区块]
    E --> F[共识竞争]
    F --> G[广播新区块]
    G --> H[验证区块]
    H --> I[追加区块]
    I --> J[交易确认]
    
      
      
      
      
      
      
      
      
      
    
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    graph TD
    A[Merkle根] --> B[哈希节点]
    A --> C[哈希节点]
    B --> D[叶子节点]
    B --> E[叶子节点]
    C --> F[叶子节点]
    C --> G[叶子节点]
    
      
      
      
      
      
      
    
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    import hashlib
    import time
    
    class Block:
    def __init__(self, index, transactions, previous_hash):
        self.index = index
        self.transactions = transactions
        self.previous_hash = previous_hash
        self.timestamp = time.time()
        self.nonce = 0
        self.hash = self.compute_hash()
    
    def compute_hash(self):
        block_string = str(self.index) + str(self.transactions) + str(self.previous_hash) + str(self.timestamp) + str(self.nonce)
        return hashlib.sha256(block_string.encode()).hexdigest()
    
    def mine_block(self, difficulty):
        while self.hash[:difficulty] != '0' * difficulty:
            self.nonce += 1
            self.hash = self.compute_hash()
        print(f"Block mined with nonce: {self.nonce}")
    
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
    
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    blockchain = [Block(0, [], '0')]  # 创建创世区块
    
    def create_block(transactions):
    previous_block = blockchain[-1]
    new_block = Block(len(blockchain), transactions, previous_block.hash)
    new_block.mine_block(2)  # 设置难度目标为2
    blockchain.append(new_block)
    
    create_block([{'sender': 'Alice', 'receiver': 'Bob', 'amount': 5}])
    create_block([{'sender': 'Bob', 'receiver': 'Charlie', 'amount': 2}])
    
      
      
      
      
      
      
      
      
      
    
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    def is_valid_chain(chain):
    for i in range(1, len(chain)):
        current_block = chain[i]
        previous_block = chain[i - 1]
    
        if current_block.hash != current_block.compute_hash():
            print(f"Block {i} has been tampered with!")
            return False
    
        if current_block.previous_hash != previous_block.hash:
            print(f"Block {i} has an invalid previous hash!")
            return False
    
    return True
    
    print(is_valid_chain(blockchain))  # 输出: True
    
      
      
      
      
      
      
      
      
      
      
      
      
      
      
      
    
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