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https://github.com/danog/tgseclib.git
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519 lines
16 KiB
PHP
519 lines
16 KiB
PHP
<?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 RC4.
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*
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* Uses mcrypt, if available, and an internal implementation, otherwise.
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*
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* PHP versions 4 and 5
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*
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* Useful resources are as follows:
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*
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* - {@link http://www.mozilla.org/projects/security/pki/nss/draft-kaukonen-cipher-arcfour-03.txt ARCFOUR Algorithm}
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* - {@link http://en.wikipedia.org/wiki/RC4 - Wikipedia: RC4}
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*
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* RC4 is also known as ARCFOUR or ARC4. The reason is elaborated upon at Wikipedia. This class is named RC4 and not
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* ARCFOUR or ARC4 because RC4 is how it is refered to in the SSH1 specification.
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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/RC4.php');
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*
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* $rc4 = new Crypt_RC4();
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*
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* $rc4->setKey('abcdefgh');
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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 $rc4->decrypt($rc4->encrypt($plaintext));
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* ?>
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* </code>
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*
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* LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*
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* @category Crypt
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* @package Crypt_RC4
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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.opensource.org/licenses/mit-license.html MIT License
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* @version $Id: RC4.php,v 1.8 2009/06/09 04:00:38 terrafrost Exp $
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* @link http://phpseclib.sourceforge.net
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*/
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/**#@+
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* @access private
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* @see Crypt_RC4::Crypt_RC4()
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*/
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/**
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* Toggles the internal implementation
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*/
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define('CRYPT_RC4_MODE_INTERNAL', 1);
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/**
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* Toggles the mcrypt implementation
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*/
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define('CRYPT_RC4_MODE_MCRYPT', 2);
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/**#@-*/
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/**#@+
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* @access private
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* @see Crypt_RC4::_crypt()
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*/
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define('CRYPT_RC4_ENCRYPT', 0);
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define('CRYPT_RC4_DECRYPT', 1);
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/**#@-*/
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/**
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* Pure-PHP implementation of RC4.
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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_RC4
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*/
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class Crypt_RC4 {
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/**
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* The Key
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*
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* @see Crypt_RC4::setKey()
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* @var String
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* @access private
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*/
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var $key = "\0";
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/**
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* The Key Stream for encryption
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*
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* If CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT, this will be equal to the mcrypt object
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*
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* @see Crypt_RC4::setKey()
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* @var Array
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* @access private
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*/
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var $encryptStream = false;
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/**
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* The Key Stream for decryption
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*
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* If CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT, this will be equal to the mcrypt object
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*
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* @see Crypt_RC4::setKey()
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* @var Array
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* @access private
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*/
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var $decryptStream = false;
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/**
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* The $i and $j indexes for encryption
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*
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* @see Crypt_RC4::_crypt()
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* @var Integer
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* @access private
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*/
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var $encryptIndex = 0;
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/**
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* The $i and $j indexes for decryption
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*
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* @see Crypt_RC4::_crypt()
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* @var Integer
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* @access private
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*/
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var $decryptIndex = 0;
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/**
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* The Encryption Algorithm
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*
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* Only used if CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT. Only possible values are MCRYPT_RC4 or MCRYPT_ARCFOUR.
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*
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* @see Crypt_RC4::Crypt_RC4()
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* @var Integer
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* @access private
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*/
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var $mode;
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/**
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* Continuous Buffer status
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*
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* @see Crypt_RC4::enableContinuousBuffer()
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* @var Boolean
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* @access private
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*/
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var $continuousBuffer = false;
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/**
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* Default Constructor.
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*
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* Determines whether or not the mcrypt extension should be used.
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*
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* @return Crypt_RC4
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* @access public
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*/
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function Crypt_RC4()
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{
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if ( !defined('CRYPT_RC4_MODE') ) {
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switch (true) {
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case extension_loaded('mcrypt') && (defined('MCRYPT_ARCFOUR') || defined('MCRYPT_RC4')) && in_array('arcfour', mcrypt_list_algorithms()):
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define('CRYPT_RC4_MODE', CRYPT_RC4_MODE_MCRYPT);
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break;
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default:
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define('CRYPT_RC4_MODE', CRYPT_RC4_MODE_INTERNAL);
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}
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}
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switch ( CRYPT_RC4_MODE ) {
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case CRYPT_RC4_MODE_MCRYPT:
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switch (true) {
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case defined('MCRYPT_ARCFOUR'):
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$this->mode = MCRYPT_ARCFOUR;
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break;
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case defined('MCRYPT_RC4');
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$this->mode = MCRYPT_RC4;
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}
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$this->encryptStream = mcrypt_module_open($this->mode, '', MCRYPT_MODE_STREAM, '');
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$this->decryptStream = mcrypt_module_open($this->mode, '', MCRYPT_MODE_STREAM, '');
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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 between 1 and 256 bytes long. If they are longer then 256 bytes, the first 256 bytes will
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* be used. If no key is explicitly set, it'll be assumed to be a single null byte.
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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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$this->key = $key;
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if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {
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mcrypt_generic_init($this->encryptStream, $this->key, '');
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mcrypt_generic_init($this->decryptStream, $this->key, '');
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return;
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}
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$keyLength = strlen($key);
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$keyStream = array();
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for ($i = 0; $i < 256; $i++) {
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$keyStream[$i] = $i;
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}
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$j = 0;
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for ($i = 0; $i < 256; $i++) {
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$j = ($j + $keyStream[$i] + ord($key[$i % $keyLength])) & 255;
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$temp = $keyStream[$i];
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$keyStream[$i] = $keyStream[$j];
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$keyStream[$j] = $temp;
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}
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$this->encryptIndex = $this->decryptIndex = array(0, 0);
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$this->encryptStream = $this->decryptStream = $keyStream;
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}
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/**
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* Sets the password.
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*
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* Depending on what $method is set to, setPassword()'s (optional) parameters are as follows:
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* {@link http://en.wikipedia.org/wiki/PBKDF2 pbkdf2}:
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* $hash, $salt, $count, $dkLen
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*
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* @param String $password
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* @param optional String $method
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* @access public
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*/
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function setPassword($password, $method = 'pbkdf2')
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{
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$key = '';
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switch ($method) {
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default: // 'pbkdf2'
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list(, , $hash, $salt, $count) = func_get_args();
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if (!isset($hash)) {
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$hash = 'sha1';
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}
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// WPA and WPA2 use the SSID as the salt
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if (!isset($salt)) {
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$salt = 'phpseclib/salt';
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}
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// RFC2898#section-4.2 uses 1,000 iterations by default
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// WPA and WPA2 use 4,096.
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if (!isset($count)) {
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$count = 1000;
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}
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if (!isset($dkLen)) {
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$dkLen = 128;
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}
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if (!class_exists('Crypt_Hash')) {
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require_once('Crypt/Hash.php');
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}
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$i = 1;
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while (strlen($key) < $dkLen) {
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//$dk.= $this->_pbkdf($password, $salt, $count, $i++);
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$hmac = new Crypt_Hash();
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$hmac->setHash($hash);
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$hmac->setKey($password);
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$f = $u = $hmac->hash($salt . pack('N', $i++));
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for ($j = 2; $j <= $count; $j++) {
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$u = $hmac->hash($u);
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$f^= $u;
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}
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$key.= $f;
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}
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}
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$this->setKey(substr($key, 0, $dkLen));
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}
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/**
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* Dummy function.
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*
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* Some protocols, such as WEP, prepend an "initialization vector" to the key, effectively creating a new key [1].
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* If you need to use an initialization vector in this manner, feel free to prepend it to the key, yourself, before
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* calling setKey().
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*
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* [1] WEP's initialization vectors (IV's) are used in a somewhat insecure way. Since, in that protocol,
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* the IV's are relatively easy to predict, an attack described by
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* {@link http://www.drizzle.com/~aboba/IEEE/rc4_ksaproc.pdf Scott Fluhrer, Itsik Mantin, and Adi Shamir}
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* can be used to quickly guess at the rest of the key. The following links elaborate:
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*
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* {@link http://www.rsa.com/rsalabs/node.asp?id=2009 http://www.rsa.com/rsalabs/node.asp?id=2009}
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* {@link http://en.wikipedia.org/wiki/Related_key_attack http://en.wikipedia.org/wiki/Related_key_attack}
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*
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* @param String $iv
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* @see Crypt_RC4::setKey()
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* @access public
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*/
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function setIV($iv)
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{
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}
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/**
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* Encrypts a message.
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*
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* @see Crypt_RC4::_crypt()
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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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return $this->_crypt($plaintext, CRYPT_RC4_ENCRYPT);
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}
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/**
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* Decrypts a message.
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*
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* $this->decrypt($this->encrypt($plaintext)) == $this->encrypt($this->encrypt($plaintext)).
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* Atleast if the continuous buffer is disabled.
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*
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* @see Crypt_RC4::_crypt()
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* @access public
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* @param String $ciphertext
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*/
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function decrypt($ciphertext)
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{
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return $this->_crypt($ciphertext, CRYPT_RC4_DECRYPT);
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}
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/**
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* Encrypts or decrypts a message.
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*
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* @see Crypt_RC4::encrypt()
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* @see Crypt_RC4::decrypt()
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* @access private
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* @param String $text
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* @param Integer $mode
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*/
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function _crypt($text, $mode)
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{
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if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {
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$keyStream = $mode == CRYPT_RC4_ENCRYPT ? 'encryptStream' : 'decryptStream';
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if (!$this->continuousBuffer) {
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mcrypt_generic_init($this->$keyStream, $this->key, '');
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}
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return mcrypt_generic($this->$keyStream, $text);
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}
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if ($this->encryptStream === false) {
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$this->setKey($this->key);
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}
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switch ($mode) {
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case CRYPT_RC4_ENCRYPT:
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$keyStream = $this->encryptStream;
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list($i, $j) = $this->encryptIndex;
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break;
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case CRYPT_RC4_DECRYPT:
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$keyStream = $this->decryptStream;
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list($i, $j) = $this->decryptIndex;
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}
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$newText = '';
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for ($k = 0; $k < strlen($text); $k++) {
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$i = ($i + 1) & 255;
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$j = ($j + $keyStream[$i]) & 255;
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$temp = $keyStream[$i];
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$keyStream[$i] = $keyStream[$j];
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$keyStream[$j] = $temp;
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$temp = $keyStream[($keyStream[$i] + $keyStream[$j]) & 255];
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$newText.= chr(ord($text[$k]) ^ $temp);
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}
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if ($this->continuousBuffer) {
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switch ($mode) {
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case CRYPT_RC4_ENCRYPT:
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$this->encryptStream = $keyStream;
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$this->encryptIndex = array($i, $j);
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break;
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case CRYPT_RC4_DECRYPT:
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$this->decryptStream = $keyStream;
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$this->decryptIndex = array($i, $j);
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}
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}
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return $newText;
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}
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/**
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* Treat consecutive "packets" as if they are a continuous buffer.
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*
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* Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets
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* will yield different outputs:
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*
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* <code>
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* echo $rc4->encrypt(substr($plaintext, 0, 8));
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* echo $rc4->encrypt(substr($plaintext, 8, 8));
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* </code>
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* <code>
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* echo $rc4->encrypt($plaintext);
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* </code>
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*
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* The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates
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* another, as demonstrated with the following:
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*
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* <code>
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* $rc4->encrypt(substr($plaintext, 0, 8));
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* echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8)));
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* </code>
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* <code>
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* echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8)));
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* </code>
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*
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* With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different
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* outputs. The reason is due to the fact that the initialization vector's change after every encryption /
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* decryption round when the continuous buffer is enabled. When it's disabled, they remain constant.
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*
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* Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each
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* encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that
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* continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them),
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* however, they are also less intuitive and more likely to cause you problems.
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*
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* @see Crypt_RC4::disableContinuousBuffer()
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* @access public
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*/
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function enableContinuousBuffer()
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{
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if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {
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mcrypt_generic_init($this->encryptStream, $this->key, '');
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mcrypt_generic_init($this->decryptStream, $this->key, '');
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}
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$this->continuousBuffer = true;
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}
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/**
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* Treat consecutive packets as if they are a discontinuous buffer.
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*
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* The default behavior.
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*
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* @see Crypt_RC4::enableContinuousBuffer()
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* @access public
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*/
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function disableContinuousBuffer()
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{
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if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_INTERNAL ) {
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$this->encryptIndex = $this->decryptIndex = array(0, 0);
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$this->encryptStream = $this->decryptStream = false;
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}
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$this->continuousBuffer = false;
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}
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/**
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* Dummy function.
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*
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* Since RC4 is a stream cipher and not a block cipher, no padding is necessary. The only reason this function is
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* included is so that you can switch between a block cipher and a stream cipher transparently.
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*
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* @see Crypt_RC4::disablePadding()
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* @access public
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*/
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function enablePadding()
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{
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}
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/**
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* Dummy function.
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*
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* @see Crypt_RC4::enablePadding()
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* @access public
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*/
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function disablePadding()
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{
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}
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/**
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* Class destructor.
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*
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* Will be called, automatically, if you're using PHP5. If you're using PHP4, call it yourself. Only really
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* needs to be called if mcrypt is being used.
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*
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* @access public
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*/
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function __destruct()
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{
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if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) {
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$this->_closeMCrypt();
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}
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}
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/**
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* Properly close the MCrypt objects.
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*
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* @access prviate
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*/
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function _closeMCrypt()
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{
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mcrypt_module_close($this->encryptStream);
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mcrypt_module_close($this->decryptStream);
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}
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}
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// vim: ts=4:sw=4:et:
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// vim6: fdl=1:
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