了解一下PHP中的简单加密函数：crypt()，一般在基于Apache的环境下，有很好的配合，可以通过一个简单的实例验证函数来说明crypt()的应用：
<?php
$host = "localhost";
$user = "teuser";
$pswd = "teword";
$db = "users";
$authorization = 0;
if (isset($PHP_AUTH_USER) && isset($PHP_AUTH_PW)) :
mysql_pconnect($host, $user, $pswd) or die("Can't connect to MySQL
server!");
mysql_select_db($db) or die("Can't select database!");
$salt = substr($PHP_AUTH_PW, 0, 2);
$encrypted_pswd = crypt($PHP_AUTH_PW, $salt);
$query = "SELECT username FROM members WHERE
username = '$PHP_AUTH_USER' AND
password = '$encrypted_pswd'";
if (mysql_numrows(mysql_query($query)) == 1) :
$authorization = 1;
endif;
endif;
if (! $authorization) :
header('WWW-Authenticate: Basic realm="Private"');
header('HTTP/1.0 401 Unauthorized');
print "You are unauthorized to enter this area.";
exit;
else :
print "This is the secret data!";
endif;
?>