<?php 
 $str = '应用crypt()函数进行单向加密!';     //声明字符串变量$str 
 echo '加密前$str的值为：'.$str; 
 $crypttostr = crypt($str);      //对变量$str加密 
 echo '<p>加密后$str的值为：'.$crypttostr;  //输出加密后的变量 
?> 

<!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" /> 
<title>使用crypt函数进行数据验证</title> 
<style type="text/css"> 
<!-- 
body,td,th { 
 font-size: 12px; 
} 
body { 
 margin-left: 10px; 
 margin-top: 10px; 
 margin-right: 10px; 
 margin-bottom: 10px; 
} 
.STYLE1 { 
 font-size: 14px; 
 font-weight: bold; 
} 
--> 
</style> 
</head> 
<body> 
<div align="center"> 
<?php 
 $conn = mysql_connect("localhost","root","root") or die("数据库链接错误".mysql_error()); 
 mysql_select_db("db_database21",$conn) or die("数据库访问错误".mysql_error()); 
 mysql_query("set names gb2312"); 
?> 
</div> 
<table width="777" height="587" border="0" align="center" cellpadding="0" cellspacing="0" background="images/bg.jpg"> 
 <tr> 
 <td width="149" height="200"> </td> 
 <td width="448"> </td> 
 <td width="158"> </td> 
 </tr> 
 <tr> 
 <td height="187"> </td> 
 <td align="center" valign="middle"> <form id="form1" name="form1" method="post" action="index.php"> 
 <table height="129" border="0" cellpadding="0" cellspacing="0"> 
  <tr> 
   <td width="100" height="30" align="right" valign="middle" scope="col"><span class="STYLE1">用户名：</span></td> 
  <td width="100" height="30" align="left" valign="middle" scope="col"><label for="textfield"></label> 
  <input name="username" type="text" id="username" size="24" /></td> 
  <td width="100" align="center" valign="middle" scope="col"> </td> 
  </tr> 
  <tr> 
  <td height="30" align="right" valign="middle" class="STYLE1" scope="col">密码：</td> 
  <td height="30" align="left" valign="middle" scope="col"><input name="password" type="password" id="password" size="25" /></td> 
  <td align="center" valign="middle" scope="col"> </td> 
  </tr> 
  <tr> 
  <td height="40" colspan="3" align="center" valign="middle" scope="col"><input type="image" name="imageField" src="images/bg2.JPG" />   
     <input type="image" name="imageField2" src="images/bg1.JPG" onclick="form.reset();return false;" /></td> 
  </tr> 
 </table> 
 </form> 
 <?php 
 if(trim($_POST[username])!= "" and trim($_POST[password])!= ""){ 
  $usr = crypt(trim($_POST[username]),$_POST[username]); 
  $pwd = crypt(trim($_POST[password]),$_POST[password]); 
  $sql = "select * from tb_user where username = '".$usr."' and password='".$pwd."'"; 
  $rst = mysql_query($sql,$conn); 
  $result=mysql_num_rows($rst); 
  if($result>0){ 
   echo "<font color='red'>用户登录成功。</font>"; 
  }else{ 
   echo "<font color='green'>用户登录失败!</font>"; 
  } 
 }else{ 
  echo "请认真填写用户名和密码！"; 
 } 
?></td> 
 <td> </td> 
 </tr> 
 <tr> 
 <td height="200"> </td> 
 <td> </td> 
 <td> </td> 
 </tr> 
</table> 
</body> 
</html>