前端常用加密方式及使用方法示例代码

// 1. 准备数据
const text = "123456";
const encoder = new TextEncoder();
const data = encoder.encode(text);

// 2. 计算哈希
const hashBuffer = await crypto.subtle.digest('SHA-256', data);

// 3. 转为十六进制
const hashArray = Array.from(new Uint8Array(hashBuffer));
const hashHex = hashArray.map(b => b.toString(16).padStart(2, '0')).join('');

console.log("SHA-256:", hashHex);
// 输出: 8d969eef6ecad3c29a3a629280e686cf0c3f5d5a86aff3ca12020c923adc6c92

// 最简单的AES加密解密
async function aesSimple() {
  // 1. 生成密钥
  const key = await crypto.subtle.generateKey(
    {name: "AES-GCM", length: 256}, true, ["encrypt", "decrypt"]
  );
  
  // 2. 加密
  const iv = crypto.getRandomValues(new Uint8Array(12));
  const encrypted = await crypto.subtle.encrypt(
    {name: "AES-GCM", iv}, key, new TextEncoder().encode("你好世界")
  );
  
  // 3. 解密
  const decrypted = await crypto.subtle.decrypt(
    {name: "AES-GCM", iv}, key, encrypted
  );
  
  console.log("结果:", new TextDecoder().decode(decrypted)); // 你好世界
}
aesSimple();

// ECC 密钥交换完整流程演示
class ECCFlow {
  static async demonstrateCompleteFlow() {
    console.log("ECC 密钥交换完整流程演示");
    console.log("==========================");
    
    // 第1步：选择椭圆曲线
    console.log("\n第1步：选择椭圆曲线");
    const curve = "P-256";
    console.log("   选择的曲线: " + curve);
    console.log("   安全强度: 128位");
    console.log("   公钥长度: 65字节");
    console.log("   私钥长度: 32字节");
    
    // 第2步：双方生成密钥对
    console.log("\n第2步：双方生成密钥对");
    
    // Alice 生成密钥对
    const aliceKeyPair = await crypto.subtle.generateKey(
      { name: "ECDH", namedCurve: curve },
      true,
      ["deriveKey"]
    );
    console.log("   Alice 生成密钥对:");
    console.log("     - 私钥: 保密存储");
    console.log("     - 公钥: 准备发送给 Bob");
    
    // Bob 生成密钥对
    const bobKeyPair = await crypto.subtle.generateKey(
      { name: "ECDH", namedCurve: curve },
      true,
      ["deriveKey"]
    );
    console.log("   Bob 生成密钥对:");
    console.log("     - 私钥: 保密存储");
    console.log("     - 公钥: 准备发送给 Alice");
    
    // 第3步：交换公钥
    console.log("\n第3步：交换公钥（通过网络）");
    
    const bobPublicKey = bobKeyPair.publicKey;
    console.log("   Alice 收到 Bob 的公钥");
    
    const alicePublicKey = aliceKeyPair.publicKey;
    console.log("   Bob 收到 Alice 的公钥");
    
    // 第4步：计算共享密钥
    console.log("\n第4步：各自计算共享密钥");
    console.log("   数学原理:");
    console.log("   Alice私钥 × Bob公钥 = Bob私钥 × Alice公钥");
    
    // Alice 计算共享密钥
    const aliceSharedKey = await crypto.subtle.deriveKey(
      {
        name: "ECDH",
        public: bobPublicKey
      },
      aliceKeyPair.privateKey,
      { name: "AES-GCM", length: 256 },
      true,
      ["encrypt", "decrypt"]
    );
    console.log("   Alice 计算共享密钥完成");
    
    // Bob 计算共享密钥
    const bobSharedKey = await crypto.subtle.deriveKey(
      {
        name: "ECDH",
        public: alicePublicKey
      },
      bobKeyPair.privateKey,
      { name: "AES-GCM", length: 256 },
      true,
      ["encrypt", "decrypt"]
    );
    console.log("   Bob 计算共享密钥完成");
    
    // 第5步：验证密钥相同
    console.log("\n第5步：验证双方密钥相同");
    
    const aliceKeyBytes = await crypto.subtle.exportKey("raw", aliceSharedKey);
    const bobKeyBytes = await crypto.subtle.exportKey("raw", bobSharedKey);
    
    const aliceHex = Array.from(new Uint8Array(aliceKeyBytes))
      .map(b => b.toString(16).padStart(2, '0'))
      .join('');
    
    const bobHex = Array.from(new Uint8Array(bobKeyBytes))
      .map(b => b.toString(16).padStart(2, '0'))
      .join('');
    
    console.log("   验证结果:");
    console.log("   Alice 密钥: " + aliceHex.substring(0, 32) + "...");
    console.log("   Bob 密钥:   " + bobHex.substring(0, 32) + "...");
    console.log("   是否相同: " + (aliceHex === bobHex ? "是" : "否"));
    
    // 第6步：使用共享密钥加密通信
    console.log("\n第6步：使用共享密钥加密通信");
    
    const message = "会议时间改为下午2点";
    console.log("   Alice 要发送: \"" + message + "\"");
    
    // 加密
    const iv = crypto.getRandomValues(new Uint8Array(12));
    const encrypted = await crypto.subtle.encrypt(
      { name: "AES-GCM", iv },
      aliceSharedKey,
      new TextEncoder().encode(message)
    );
    
    console.log("   加密完成:");
    console.log("     - 密文长度: " + encrypted.byteLength + " 字节");
    console.log("     - IV: " + Array.from(iv).slice(0, 3).join(',') + "...");
    
    // 第7步：Bob 解密消息
    console.log("\n第7步：Bob 解密消息");
    
    const decrypted = await crypto.subtle.decrypt(
      { name: "AES-GCM", iv },
      bobSharedKey,
      encrypted
    );
    
    const decryptedMessage = new TextDecoder().decode(decrypted);
    console.log("   Bob 解密得到: \"" + decryptedMessage + "\"");
    console.log("   是否正确: " + (message === decryptedMessage ? "是" : "否"));
    
    // 安全性分析
    console.log("\n安全性分析:");
    console.log("   中间人无法计算共享密钥");
    console.log("   即使窃听到公钥交换也没用");
    console.log("   每次会话可生成新的密钥对");
    
    return {
      aliceKeyPair,
      bobKeyPair,
      sharedKey: aliceSharedKey,
      encryptedMessage: encrypted
    };
  }
}

// 运行完整流程
ECCFlow.demonstrateCompleteFlow().catch(console.error);