密码是什么啊

<?php
/*****************************
* login.php 登录验证处理文件
*****************************/
session_start();
// 注销登录
if($_GET['action'] == 'logout'){
session_unregister("username");
exit('<script language="javascript">alert("退出成功！");self.location = "login.php";</script>');
}// 如果检测到已登录，直接跳转至管理页面
if(isset($_SESSION['username'])){
header("Location: http://".$_SERVER['HTTP_HOST'].rtrim(dirname($_SERVER['PHP_SELF']), '/\\')."/admin.php");
exit;
}
if($_POST){
require("./conn.php");
$username = $_POST['username'];
$password = MD5(trim($_POST['password']));
$check_result = mysql_query("SELECT uid FROM user WHERE username = '$username' AND password = '$password'");
if(mysql_fetch_array($check_result)){
session_register("username");
header("Location: http://".$_SERVER['HTTP_HOST'].rtrim(dirname($_SERVER['PHP_SELF']), '/\\')."/admin.php");
exit;
} else {
echo '<script language="javascript">alert("密码错误！");self.location = "login.php";</script>';
}
}?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<link rel="stylesheet" type="text/css" href="style/style.css" />
<title>留言管理登录</title>
<script language="JavaScript">
<!--function InputCheck(form1)
{
  if (form1.password.value == "")
  {
    alert("请输入密码。");
    form1.password.focus();
    return (false);
  }
}
//--!>
</script>
</head>
<body>
<div class="login-form">
<form id="form1" name="form1" method="post" action="login.php" onSubmit="return InputCheck(this)">
<p>
<input type="hidden" name="username" value="admin" />
<label for="password">管理密码:</label>
<input id="password" name="password" type="password" />
<input type="submit" name="submit" value=" 确定 " />
 <a href="list.php">返回留言板</a>
</p>
</form>
</div>
</body>
</html>

解决方案 »

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$password = MD5(trim($_POST['password']));