昨天我接受了关于尝试散列我的用户名的教育，之后我决定使用mysql中的aesïu加密和解密函数来安全地存储我的用户名。从目前的情况来看，我可以通过以下方式对它们进行加密并将其存储在我的数据库中：

$con=mysqli_connect($servername, $dbusername, $dbpassword, $dbname);
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$stmt = $con->prepare("INSERT INTO users (username, password) VALUES (AES_ENCRYPT(?, '$aesKey'), ?)");
$stmt->bind_param("ss", $username, $password);
$username = $_POST['username'];
$plainPass = $_POST['password'];
$password = password_hash($plainPass, PASSWORD_ARGON2I);
$stmt->execute();
$stmt->close();
$con->close();
echo "<script> location.href='login.php'; </script>";
}
?>

我使用的是从配置文件加载的256位加密密钥，称为 $aesKey 但是，当我尝试登录时，我无法。什么都没发生。没有sql错误被打印出来，但是我得到了 PHP Notice: Undefined variable: username . 代码如下：

$submittedUser = $_POST['username'];
$submittedPass = $_POST['password'];

$con=mysqli_connect($servername, $dbusername, $dbpassword, $dbname);
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
if ($stmt = mysqli_prepare($con, "SELECT * FROM users Where username =AES_DECRYPT(?, '$aesKey')")) {
                    mysqli_stmt_bind_param($stmt, "s", $submittedUser);
                    mysqli_stmt_execute($stmt);
                    $result = mysqli_stmt_get_result($stmt);
                    echo mysqli_error($con);

}

while($row = mysqli_fetch_array($result))
{
$username = $row['username'];
$password = $row['password'];
}
if ($submittedUser == $username && password_verify($submittedPass, $password))
{
$_SESSION['user']=$username; 

//echo "<script> location.href='index.php'; </script>";
//        exit;   
}
else
{
 //echo "<script> location.href='login.php'; </script>";
//        exit;   
}
mysqli_close($con);
}
?>

我注解掉了重定向，因为我最初认为它们是导致错误消息无法打印的原因。有人能帮我吗？我似乎不知道什么不起作用。
编辑：我把语句改回 "SELECT * FROM users Where username =AES_ENCRYPT(?, '$aesKey')" 我收到以下输出：

Array ( [0] => 5�uY��V�s~"�ܮ� [username] => 5�uY��V�s~"�ܮ� [1] => $argon2i$v=19$m=1024,t=2,p=2$akcuREppYk1ERjRlUi5ZQw$yIdC5oMblekARArcB0XjwwmWywJ824iM8FmKqAu+9ys [password] => $argon2i$v=19$m=1024,t=2,p=2$akcuREppYk1ERjRlUi5ZQw$yIdC5oMblekARArcB0XjwwmWywJ824iM8FmKqAu+9ys )`

编辑2：这里是数据库结构。未加密的用户名应为evan，未加密的密码应为edwards。

--
-- Table structure for table `users`
--

CREATE TABLE `users` (
  `username` text NOT NULL,
  `password` text NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

--
-- Dumping data for table `users`
--

INSERT INTO `users` (`username`, `password`) VALUES
('5ÇuY¯úVõs~\"ÐÜ®€', '$argon2i$v=19$m=1024,t=2,p=2$NWZQS2Q3dE1ORndjaUdpWg$vOR3DBT+IhdAXIt7YUPDiExalf1lsMeIVe/zTZDDYfU');

编辑3:运行以下代码：

<?php

include 'config.php';
$con=mysqli_connect($servername, $dbusername, $dbpassword, $dbname);
$result = mysqli_query($con,"SELECT * FROM `users`");
while($row = mysqli_fetch_array($result))
{
echo $row['username'];
echo "<br>";
echo $row['password'];
}
mysqli_close($con);
?>

给出以下结果：

5�uY��V�s~"�ܮ�
$argon2i$v=19$m=1024,t=2,p=2$NWZQS2Q3dE1ORndjaUdpWg$vOR3DBT+IhdAXIt7YUPDiExalf1lsMeIVe/zTZDDYfU