PHP开发实时聊天功能的用户隐私和数据保护措施

function encrypt($data, $key) {
    $cipher = "AES-256-CBC";
    $iv = random_bytes(openssl_cipher_iv_length($cipher));
    $encrypted = openssl_encrypt($data, $cipher, $key, 0, $iv);
    return base64_encode($iv.$encrypted);
}

function decrypt($data, $key) {
    $cipher = "AES-256-CBC";
    $data = base64_decode($data);
    $ivLength = openssl_cipher_iv_length($cipher);
    $iv = substr($data, 0, $ivLength);
    $encrypted = substr($data, $ivLength);
    return openssl_decrypt($encrypted, $cipher, $key, 0, $iv);
}

function authenticateUser($username, $password) {
    // 根据用户名查询数据库，验证用户密码
    // 返回true/false表示验证结果
    // 示例代码仅供参考，具体实现需根据实际情况调整
    $dbUsername = "testuser";
    $dbPassword = "testpassword";
    
    if ($username == $dbUsername && $password == $dbPassword) {
        return true;
    } else {
        return false;
    }
}

// 在处理用户发送的消息前进行身份验证
if (authenticateUser($_POST['username'], $_POST['password'])) {
    // 用户身份验证通过，处理用户发送的消息
} else {
    // 身份验证失败，拒绝处理用户发送的消息
}