690 lines
23 KiB
PHP
690 lines
23 KiB
PHP
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<?php
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/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
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/**
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* Pure-PHP implementation of Triple DES.
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*
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* Uses mcrypt, if available, and an internal implementation, otherwise. Operates in the EDE3 mode (encrypt-decrypt-encrypt).
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*
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* PHP versions 4 and 5
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*
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* Here's a short example of how to use this library:
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* <code>
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* <?php
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* include('Crypt/TripleDES.php');
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*
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* $des = new Crypt_TripleDES();
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*
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* $des->setKey('abcdefghijklmnopqrstuvwx');
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*
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* $size = 10 * 1024;
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* $plaintext = '';
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* for ($i = 0; $i < $size; $i++) {
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* $plaintext.= 'a';
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* }
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*
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* echo $des->decrypt($des->encrypt($plaintext));
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* ?>
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* </code>
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*
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* LICENSE: This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*
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* @category Crypt
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* @package Crypt_TripleDES
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* @author Jim Wigginton <terrafrost@php.net>
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* @copyright MMVII Jim Wigginton
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* @license http://www.gnu.org/licenses/lgpl.txt
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* @version $Id$
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* @link http://phpseclib.sourceforge.net
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*/
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/**
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* Include Crypt_DES
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*/
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require_once 'DES.php';
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/**
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* Encrypt / decrypt using inner chaining
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*
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* Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (CRYPT_DES_MODE_CBC3).
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*/
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define('CRYPT_DES_MODE_3CBC', 3);
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/**
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* Encrypt / decrypt using outer chaining
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*
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* Outer chaining is used by SSH-2 and when the mode is set to CRYPT_DES_MODE_CBC.
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*/
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define('CRYPT_DES_MODE_CBC3', CRYPT_DES_MODE_CBC);
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/**
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* Pure-PHP implementation of Triple DES.
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*
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* @author Jim Wigginton <terrafrost@php.net>
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* @version 0.1.0
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* @access public
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* @package Crypt_TerraDES
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*/
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class Crypt_TripleDES {
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/**
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* The Three Keys
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*
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* @see Crypt_TripleDES::setKey()
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* @var String
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* @access private
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*/
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var $key = "\0\0\0\0\0\0\0\0";
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/**
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* The Encryption Mode
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*
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* @see Crypt_TripleDES::Crypt_TripleDES()
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* @var Integer
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* @access private
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*/
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var $mode = CRYPT_DES_MODE_CBC;
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/**
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* Continuous Buffer status
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*
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* @see Crypt_TripleDES::enableContinuousBuffer()
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* @var Boolean
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* @access private
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*/
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var $continuousBuffer = false;
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/**
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* Padding status
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*
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* @see Crypt_TripleDES::enablePadding()
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* @var Boolean
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* @access private
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*/
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var $padding = true;
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/**
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* The Initialization Vector
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*
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* @see Crypt_TripleDES::setIV()
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* @var String
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* @access private
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*/
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var $iv = "\0\0\0\0\0\0\0\0";
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/**
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* A "sliding" Initialization Vector
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*
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* @see Crypt_TripleDES::enableContinuousBuffer()
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* @var String
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* @access private
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*/
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var $encryptIV = "\0\0\0\0\0\0\0\0";
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/**
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* A "sliding" Initialization Vector
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*
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* @see Crypt_TripleDES::enableContinuousBuffer()
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* @var String
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* @access private
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*/
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var $decryptIV = "\0\0\0\0\0\0\0\0";
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/**
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* The Crypt_DES objects
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*
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* @var Array
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* @access private
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*/
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var $des;
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/**
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* mcrypt resource for encryption
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*
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* The mcrypt resource can be recreated every time something needs to be created or it can be created just once.
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* Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.
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*
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* @see Crypt_AES::encrypt()
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* @var String
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* @access private
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*/
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var $enmcrypt;
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/**
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* mcrypt resource for decryption
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*
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* The mcrypt resource can be recreated every time something needs to be created or it can be created just once.
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* Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.
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*
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* @see Crypt_AES::decrypt()
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* @var String
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* @access private
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*/
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var $demcrypt;
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/**
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* Does the (en|de)mcrypt resource need to be (re)initialized?
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*
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* @see setKey()
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* @see setIV()
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* @var Boolean
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* @access private
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*/
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var $changed = true;
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/**
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* Default Constructor.
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*
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* Determines whether or not the mcrypt extension should be used. $mode should only, at present, be
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* CRYPT_DES_MODE_ECB or CRYPT_DES_MODE_CBC. If not explictly set, CRYPT_DES_MODE_CBC will be used.
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*
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* @param optional Integer $mode
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* @return Crypt_TripleDES
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* @access public
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*/
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function Crypt_TripleDES($mode = CRYPT_DES_MODE_CBC)
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{
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if ( !defined('CRYPT_DES_MODE') ) {
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switch (true) {
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case extension_loaded('mcrypt'):
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// i'd check to see if des was supported, by doing in_array('des', mcrypt_list_algorithms('')),
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// but since that can be changed after the object has been created, there doesn't seem to be
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// a lot of point...
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define('CRYPT_DES_MODE', CRYPT_DES_MODE_MCRYPT);
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break;
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default:
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define('CRYPT_DES_MODE', CRYPT_DES_MODE_INTERNAL);
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}
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}
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if ( $mode == CRYPT_DES_MODE_3CBC ) {
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$this->mode = CRYPT_DES_MODE_3CBC;
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$this->des = array(
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new Crypt_DES(CRYPT_DES_MODE_CBC),
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new Crypt_DES(CRYPT_DES_MODE_CBC),
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new Crypt_DES(CRYPT_DES_MODE_CBC)
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);
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// we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects
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$this->des[0]->disablePadding();
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$this->des[1]->disablePadding();
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$this->des[2]->disablePadding();
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return;
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}
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switch ( CRYPT_DES_MODE ) {
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case CRYPT_DES_MODE_MCRYPT:
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switch ($mode) {
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case CRYPT_DES_MODE_ECB:
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$this->mode = MCRYPT_MODE_ECB;
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break;
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case CRYPT_DES_MODE_CTR:
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$this->mode = 'ctr';
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break;
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case CRYPT_DES_MODE_CBC:
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default:
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$this->mode = MCRYPT_MODE_CBC;
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}
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break;
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default:
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$this->des = array(
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new Crypt_DES(CRYPT_DES_MODE_ECB),
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new Crypt_DES(CRYPT_DES_MODE_ECB),
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new Crypt_DES(CRYPT_DES_MODE_ECB)
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);
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// we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects
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$this->des[0]->disablePadding();
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$this->des[1]->disablePadding();
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$this->des[2]->disablePadding();
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switch ($mode) {
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case CRYPT_DES_MODE_ECB:
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case CRYPT_DES_MODE_CTR:
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case CRYPT_DES_MODE_CBC:
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$this->mode = $mode;
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break;
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default:
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$this->mode = CRYPT_DES_MODE_CBC;
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}
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}
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}
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/**
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* Sets the key.
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*
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* Keys can be of any length. Triple DES, itself, can use 128-bit (eg. strlen($key) == 16) or
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* 192-bit (eg. strlen($key) == 24) keys. This function pads and truncates $key as appropriate.
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*
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* DES also requires that every eighth bit be a parity bit, however, we'll ignore that.
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*
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* If the key is not explicitly set, it'll be assumed to be all zero's.
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*
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* @access public
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* @param String $key
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*/
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function setKey($key)
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{
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$length = strlen($key);
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if ($length > 8) {
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$key = str_pad($key, 24, chr(0));
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// if $key is between 64 and 128-bits, use the first 64-bits as the last, per this:
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// http://php.net/function.mcrypt-encrypt#47973
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//$key = $length <= 16 ? substr_replace($key, substr($key, 0, 8), 16) : substr($key, 0, 24);
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}
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$this->key = $key;
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switch (true) {
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case CRYPT_DES_MODE == CRYPT_DES_MODE_INTERNAL:
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case $this->mode == CRYPT_DES_MODE_3CBC:
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$this->des[0]->setKey(substr($key, 0, 8));
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$this->des[1]->setKey(substr($key, 8, 8));
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$this->des[2]->setKey(substr($key, 16, 8));
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}
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$this->changed = true;
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}
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/**
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* Sets the initialization vector. (optional)
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*
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* SetIV is not required when CRYPT_DES_MODE_ECB is being used. If not explictly set, it'll be assumed
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* to be all zero's.
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*
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* @access public
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* @param String $iv
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*/
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function setIV($iv)
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{
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$this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($iv, 0, 8), 8, chr(0));
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if ($this->mode == CRYPT_DES_MODE_3CBC) {
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$this->des[0]->setIV($iv);
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$this->des[1]->setIV($iv);
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$this->des[2]->setIV($iv);
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}
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$this->changed = true;
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}
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/**
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* Generate CTR XOR encryption key
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*
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* Encrypt the output of this and XOR it against the ciphertext / plaintext to get the
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* plaintext / ciphertext in CTR mode.
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*
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* @see Crypt_DES::decrypt()
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* @see Crypt_DES::encrypt()
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* @access public
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* @param Integer $length
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* @param String $iv
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*/
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function _generate_xor($length, &$iv)
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{
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$xor = '';
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$num_blocks = ($length + 7) >> 3;
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for ($i = 0; $i < $num_blocks; $i++) {
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$xor.= $iv;
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for ($j = 4; $j <= 8; $j+=4) {
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$temp = substr($iv, -$j, 4);
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switch ($temp) {
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case "\xFF\xFF\xFF\xFF":
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$iv = substr_replace($iv, "\x00\x00\x00\x00", -$j, 4);
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break;
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case "\x7F\xFF\xFF\xFF":
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$iv = substr_replace($iv, "\x80\x00\x00\x00", -$j, 4);
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break 2;
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default:
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extract(unpack('Ncount', $temp));
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$iv = substr_replace($iv, pack('N', $count + 1), -$j, 4);
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break 2;
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}
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}
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}
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return $xor;
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}
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/**
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* Encrypts a message.
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*
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* @access public
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* @param String $plaintext
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*/
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function encrypt($plaintext)
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{
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if ($this->mode != CRYPT_DES_MODE_CTR && $this->mode != 'ctr') {
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$plaintext = $this->_pad($plaintext);
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}
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// if the key is smaller then 8, do what we'd normally do
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if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) {
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$ciphertext = $this->des[2]->encrypt($this->des[1]->decrypt($this->des[0]->encrypt($plaintext)));
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return $ciphertext;
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}
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if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) {
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if ($this->changed) {
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if (!isset($this->enmcrypt)) {
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$this->enmcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, '');
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}
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mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
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|
$this->changed = false;
|
||
|
|
}
|
||
|
|
|
||
|
|
$ciphertext = mcrypt_generic($this->enmcrypt, $plaintext);
|
||
|
|
|
||
|
|
if (!$this->continuousBuffer) {
|
||
|
|
mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
|
||
|
|
}
|
||
|
|
|
||
|
|
return $ciphertext;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (strlen($this->key) <= 8) {
|
||
|
|
$this->des[0]->mode = $this->mode;
|
||
|
|
|
||
|
|
return $this->des[0]->encrypt($plaintext);
|
||
|
|
}
|
||
|
|
|
||
|
|
// we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic :
|
||
|
|
// "The data is padded with "\0" to make sure the length of the data is n * blocksize."
|
||
|
|
$plaintext = str_pad($plaintext, ceil(strlen($plaintext) / 8) * 8, chr(0));
|
||
|
|
|
||
|
|
$des = $this->des;
|
||
|
|
|
||
|
|
$ciphertext = '';
|
||
|
|
switch ($this->mode) {
|
||
|
|
case CRYPT_DES_MODE_ECB:
|
||
|
|
for ($i = 0; $i < strlen($plaintext); $i+=8) {
|
||
|
|
$block = substr($plaintext, $i, 8);
|
||
|
|
$block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
|
||
|
|
$block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT);
|
||
|
|
$block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT);
|
||
|
|
$ciphertext.= $block;
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case CRYPT_DES_MODE_CBC:
|
||
|
|
$xor = $this->encryptIV;
|
||
|
|
for ($i = 0; $i < strlen($plaintext); $i+=8) {
|
||
|
|
$block = substr($plaintext, $i, 8) ^ $xor;
|
||
|
|
$block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
|
||
|
|
$block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT);
|
||
|
|
$block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT);
|
||
|
|
$xor = $block;
|
||
|
|
$ciphertext.= $block;
|
||
|
|
}
|
||
|
|
if ($this->continuousBuffer) {
|
||
|
|
$this->encryptIV = $xor;
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case CRYPT_DES_MODE_CTR:
|
||
|
|
$xor = $this->encryptIV;
|
||
|
|
for ($i = 0; $i < strlen($plaintext); $i+=8) {
|
||
|
|
$key = $this->_generate_xor(8, $xor);
|
||
|
|
$key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
|
||
|
|
$key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
|
||
|
|
$key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
|
||
|
|
$block = substr($plaintext, $i, 8);
|
||
|
|
$ciphertext.= $block ^ $key;
|
||
|
|
}
|
||
|
|
if ($this->continuousBuffer) {
|
||
|
|
$this->encryptIV = $xor;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return $ciphertext;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Decrypts a message.
|
||
|
|
*
|
||
|
|
* @access public
|
||
|
|
* @param String $ciphertext
|
||
|
|
*/
|
||
|
|
function decrypt($ciphertext)
|
||
|
|
{
|
||
|
|
if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) {
|
||
|
|
$plaintext = $this->des[0]->decrypt($this->des[1]->encrypt($this->des[2]->decrypt($ciphertext)));
|
||
|
|
|
||
|
|
return $this->_unpad($plaintext);
|
||
|
|
}
|
||
|
|
|
||
|
|
// we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic :
|
||
|
|
// "The data is padded with "\0" to make sure the length of the data is n * blocksize."
|
||
|
|
$ciphertext = str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, chr(0));
|
||
|
|
|
||
|
|
if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) {
|
||
|
|
if ($this->changed) {
|
||
|
|
if (!isset($this->demcrypt)) {
|
||
|
|
$this->demcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, '');
|
||
|
|
}
|
||
|
|
mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
|
||
|
|
$this->changed = false;
|
||
|
|
}
|
||
|
|
|
||
|
|
$plaintext = mdecrypt_generic($this->demcrypt, $ciphertext);
|
||
|
|
|
||
|
|
if (!$this->continuousBuffer) {
|
||
|
|
mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
|
||
|
|
}
|
||
|
|
|
||
|
|
return $this->mode != 'ctr' ? $this->_unpad($plaintext) : $plaintext;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (strlen($this->key) <= 8) {
|
||
|
|
$this->des[0]->mode = $this->mode;
|
||
|
|
|
||
|
|
return $this->_unpad($this->des[0]->decrypt($plaintext));
|
||
|
|
}
|
||
|
|
|
||
|
|
$des = $this->des;
|
||
|
|
|
||
|
|
$plaintext = '';
|
||
|
|
switch ($this->mode) {
|
||
|
|
case CRYPT_DES_MODE_ECB:
|
||
|
|
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
|
||
|
|
$block = substr($ciphertext, $i, 8);
|
||
|
|
$block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT);
|
||
|
|
$block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT);
|
||
|
|
$block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT);
|
||
|
|
$plaintext.= $block;
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case CRYPT_DES_MODE_CBC:
|
||
|
|
$xor = $this->decryptIV;
|
||
|
|
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
|
||
|
|
$orig = $block = substr($ciphertext, $i, 8);
|
||
|
|
$block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT);
|
||
|
|
$block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT);
|
||
|
|
$block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT);
|
||
|
|
$plaintext.= $block ^ $xor;
|
||
|
|
$xor = $orig;
|
||
|
|
}
|
||
|
|
if ($this->continuousBuffer) {
|
||
|
|
$this->decryptIV = $xor;
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
case CRYPT_DES_MODE_CTR:
|
||
|
|
$xor = $this->decryptIV;
|
||
|
|
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
|
||
|
|
$key = $this->_generate_xor(8, $xor);
|
||
|
|
$key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
|
||
|
|
$key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
|
||
|
|
$key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
|
||
|
|
$block = substr($ciphertext, $i, 8);
|
||
|
|
$plaintext.= $block ^ $key;
|
||
|
|
}
|
||
|
|
if ($this->continuousBuffer) {
|
||
|
|
$this->decryptIV = $xor;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return $this->mode != CRYPT_DES_MODE_CTR ? $this->_unpad($plaintext) : $plaintext;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Treat consecutive "packets" as if they are a continuous buffer.
|
||
|
|
*
|
||
|
|
* Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets
|
||
|
|
* will yield different outputs:
|
||
|
|
*
|
||
|
|
* <code>
|
||
|
|
* echo $des->encrypt(substr($plaintext, 0, 8));
|
||
|
|
* echo $des->encrypt(substr($plaintext, 8, 8));
|
||
|
|
* </code>
|
||
|
|
* <code>
|
||
|
|
* echo $des->encrypt($plaintext);
|
||
|
|
* </code>
|
||
|
|
*
|
||
|
|
* The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates
|
||
|
|
* another, as demonstrated with the following:
|
||
|
|
*
|
||
|
|
* <code>
|
||
|
|
* $des->encrypt(substr($plaintext, 0, 8));
|
||
|
|
* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
|
||
|
|
* </code>
|
||
|
|
* <code>
|
||
|
|
* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
|
||
|
|
* </code>
|
||
|
|
*
|
||
|
|
* With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different
|
||
|
|
* outputs. The reason is due to the fact that the initialization vector's change after every encryption /
|
||
|
|
* decryption round when the continuous buffer is enabled. When it's disabled, they remain constant.
|
||
|
|
*
|
||
|
|
* Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each
|
||
|
|
* encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that
|
||
|
|
* continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them),
|
||
|
|
* however, they are also less intuitive and more likely to cause you problems.
|
||
|
|
*
|
||
|
|
* @see Crypt_TripleDES::disableContinuousBuffer()
|
||
|
|
* @access public
|
||
|
|
*/
|
||
|
|
function enableContinuousBuffer()
|
||
|
|
{
|
||
|
|
$this->continuousBuffer = true;
|
||
|
|
if ($this->mode == CRYPT_DES_MODE_3CBC) {
|
||
|
|
$this->des[0]->enableContinuousBuffer();
|
||
|
|
$this->des[1]->enableContinuousBuffer();
|
||
|
|
$this->des[2]->enableContinuousBuffer();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Treat consecutive packets as if they are a discontinuous buffer.
|
||
|
|
*
|
||
|
|
* The default behavior.
|
||
|
|
*
|
||
|
|
* @see Crypt_TripleDES::enableContinuousBuffer()
|
||
|
|
* @access public
|
||
|
|
*/
|
||
|
|
function disableContinuousBuffer()
|
||
|
|
{
|
||
|
|
$this->continuousBuffer = false;
|
||
|
|
$this->encryptIV = $this->iv;
|
||
|
|
$this->decryptIV = $this->iv;
|
||
|
|
|
||
|
|
if ($this->mode == CRYPT_DES_MODE_3CBC) {
|
||
|
|
$this->des[0]->disableContinuousBuffer();
|
||
|
|
$this->des[1]->disableContinuousBuffer();
|
||
|
|
$this->des[2]->disableContinuousBuffer();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Pad "packets".
|
||
|
|
*
|
||
|
|
* DES works by encrypting eight bytes at a time. If you ever need to encrypt or decrypt something that's not
|
||
|
|
* a multiple of eight, it becomes necessary to pad the input so that it's length is a multiple of eight.
|
||
|
|
*
|
||
|
|
* Padding is enabled by default. Sometimes, however, it is undesirable to pad strings. Such is the case in SSH1,
|
||
|
|
* where "packets" are padded with random bytes before being encrypted. Unpad these packets and you risk stripping
|
||
|
|
* away characters that shouldn't be stripped away. (SSH knows how many bytes are added because the length is
|
||
|
|
* transmitted separately)
|
||
|
|
*
|
||
|
|
* @see Crypt_TripleDES::disablePadding()
|
||
|
|
* @access public
|
||
|
|
*/
|
||
|
|
function enablePadding()
|
||
|
|
{
|
||
|
|
$this->padding = true;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Do not pad packets.
|
||
|
|
*
|
||
|
|
* @see Crypt_TripleDES::enablePadding()
|
||
|
|
* @access public
|
||
|
|
*/
|
||
|
|
function disablePadding()
|
||
|
|
{
|
||
|
|
$this->padding = false;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Pads a string
|
||
|
|
*
|
||
|
|
* Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize (8).
|
||
|
|
* 8 - (strlen($text) & 7) bytes are added, each of which is equal to chr(8 - (strlen($text) & 7)
|
||
|
|
*
|
||
|
|
* If padding is disabled and $text is not a multiple of the blocksize, the string will be padded regardless
|
||
|
|
* and padding will, hence forth, be enabled.
|
||
|
|
*
|
||
|
|
* @see Crypt_TripleDES::_unpad()
|
||
|
|
* @access private
|
||
|
|
*/
|
||
|
|
function _pad($text)
|
||
|
|
{
|
||
|
|
$length = strlen($text);
|
||
|
|
|
||
|
|
if (!$this->padding) {
|
||
|
|
if (($length & 7) == 0) {
|
||
|
|
return $text;
|
||
|
|
} else {
|
||
|
|
user_error("The plaintext's length ($length) is not a multiple of the block size (8)", E_USER_NOTICE);
|
||
|
|
$this->padding = true;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
$pad = 8 - ($length & 7);
|
||
|
|
return str_pad($text, $length + $pad, chr($pad));
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Unpads a string
|
||
|
|
*
|
||
|
|
* If padding is enabled and the reported padding length is invalid the encryption key will be assumed to be wrong
|
||
|
|
* and false will be returned.
|
||
|
|
*
|
||
|
|
* @see Crypt_TripleDES::_pad()
|
||
|
|
* @access private
|
||
|
|
*/
|
||
|
|
function _unpad($text)
|
||
|
|
{
|
||
|
|
if (!$this->padding) {
|
||
|
|
return $text;
|
||
|
|
}
|
||
|
|
|
||
|
|
$length = ord($text[strlen($text) - 1]);
|
||
|
|
|
||
|
|
if (!$length || $length > 8) {
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
return substr($text, 0, -$length);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// vim: ts=4:sw=4:et:
|
||
|
|
// vim6: fdl=1:
|