Question

从http://fullthrottledevelopment.com/php-nonce-library#download开始，有一个PHP nonce库，但有些事情我不明白。第一个是它提醒我们为FT_NONCE_UNIQUE_KEY设置一个值，但它从不在任何函数中使用它。

第二件事是，当我调用ft_nonce_create_query_string函数时，等待几秒钟，然后使用相同的参数再次调用它，两个调用都返回相同的值。这很奇怪，我真的不明白它如何确保它生成的每个nonce，nonce将在FT_NONCE_DURATION中指定的持续时间内有效。

但如果我在第二次通话前等待更长时间，他们将返回不同的价值。我已粘贴代码here，以便您可以尝试直接运行代码。

为什么会这样？它应该如何运作？

<?php
/*
 * Name: FT-NONCE-LIB
 * Created By: Full Throttle Development, LLC (http://fullthrottledevelopment.com)
 * Created On: July 2009
 * Last Modified On: August 12, 2009
 * Last Modified By: Glenn Ansley (glenn@fullthrottledevelopment.com)
 * Version: 0.2
 */

/* 
Copyright 2009 Full Throttle Development, LLC

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

define( 'FT_NONCE_UNIQUE_KEY' , '' );
define( 'FT_NONCE_DURATION' , 300 ); // 300 makes link or form good for 5 minutes from time of generation
define( 'FT_NONCE_KEY' , '_nonce' );

// This method creates a key / value pair for a url string
function ft_nonce_create_query_string( $action = '' , $user = '' ){
 return FT_NONCE_KEY."=".ft_nonce_create( $action , $user );
}

// This method creates an nonce for a form field
function ft_nonce_create_form_input( $action = '' , $user='' ){
 echo "<input type='hidden' name='".FT_NONCE_KEY."' value='".ft_nonce_create( $action . $user )."' />";
}

// This method creates an nonce. It should be called by one of the previous two functions.
function ft_nonce_create( $action = '' , $user='' ){
 return substr( ft_nonce_generate_hash( $action . $user ), -12, 10);
}

// This method validates an nonce
function ft_nonce_is_valid( $nonce , $action = '' , $user='' ){
 // Nonce generated 0-12 hours ago
 if ( substr(ft_nonce_generate_hash( $action . $user ), -12, 10) == $nonce ){
  return true;
 }
 return false;
}

// This method generates the nonce timestamp
function ft_nonce_generate_hash( $action='' , $user='' ){
 $i = ceil( time() / ( FT_NONCE_DURATION / 2 ) );
 return md5( $i . $action . $user . $action );
}

if ( FT_NONCE_UNIQUE_KEY == '' ){ die( 'You must enter a unique key on line 2 of ft_nonce_lib.php to use this library.'); }
?>

Answer 1

哇，不要使用这个图书馆。我将在此帖后立即将此报告为漏洞。 Nonce是一个只使用一次的值，这个库确实提供了这个值。但是，作者试图阻止跨站请求伪造（XSRF）。为了防止攻击者伪造消息，需要有一个攻击者无法预测的秘密值。为此，您需要一个密码安全随机数生成器或CSRPING。这个库构建的Nonce非常容易预测，并且可以使用简单的javascript轻松强制执行。

这个PHP nonce库如何工作？

1 个答案: