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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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/** |
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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 referred 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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* @link http://phpseclib.sourceforge.net |
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*/ |
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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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/**#@+ |
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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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/** |
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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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/** |
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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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/** |
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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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/** |
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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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/** |
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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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/** |
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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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/** |
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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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/** |
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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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|
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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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|
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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 = $key; |
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|
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if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) { |
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mcrypt_generic_init($this->encryptStream, $this->key, ''); |
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mcrypt_generic_init($this->decryptStream, $this->key, ''); |
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return; |
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} |
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|
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$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] = $temp; |
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} |
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|
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$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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/** |
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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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|
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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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$dkLen = 128; |
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} |
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|
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if (!class_exists('Crypt_Hash')) { |
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require_once('Crypt/Hash.php'); |
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} |
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|
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$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.= $f; |
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} |
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} |
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|
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$this->setKey(substr($key, 0, $dkLen)); |
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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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* 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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* |
| 306 |
* @param String $iv |
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* @see Crypt_RC4::setKey() |
| 308 |
* @access public |
| 309 |
*/ |
| 310 |
function setIV($iv) |
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{ |
| 312 |
} |
| 313 |
|
| 314 |
/** |
| 315 |
* Encrypts a message. |
| 316 |
* |
| 317 |
* @see Crypt_RC4::_crypt() |
| 318 |
* @access public |
| 319 |
* @param String $plaintext |
| 320 |
*/ |
| 321 |
function encrypt($plaintext) |
| 322 |
{ |
| 323 |
return $this->_crypt($plaintext, CRYPT_RC4_ENCRYPT); |
| 324 |
} |
| 325 |
|
| 326 |
/** |
| 327 |
* Decrypts a message. |
| 328 |
* |
| 329 |
* $this->decrypt($this->encrypt($plaintext)) == $this->encrypt($this->encrypt($plaintext)). |
| 330 |
* Atleast if the continuous buffer is disabled. |
| 331 |
* |
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* @see Crypt_RC4::_crypt() |
| 333 |
* @access public |
| 334 |
* @param String $ciphertext |
| 335 |
*/ |
| 336 |
function decrypt($ciphertext) |
| 337 |
{ |
| 338 |
return $this->_crypt($ciphertext, CRYPT_RC4_DECRYPT); |
| 339 |
} |
| 340 |
|
| 341 |
/** |
| 342 |
* Encrypts or decrypts a message. |
| 343 |
* |
| 344 |
* @see Crypt_RC4::encrypt() |
| 345 |
* @see Crypt_RC4::decrypt() |
| 346 |
* @access private |
| 347 |
* @param String $text |
| 348 |
* @param Integer $mode |
| 349 |
*/ |
| 350 |
function _crypt($text, $mode) |
| 351 |
{ |
| 352 |
if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) { |
| 353 |
$keyStream = $mode == CRYPT_RC4_ENCRYPT ? 'encryptStream' : 'decryptStream'; |
| 354 |
|
| 355 |
if (!$this->continuousBuffer) { |
| 356 |
mcrypt_generic_init($this->$keyStream, $this->key, ''); |
| 357 |
} |
| 358 |
|
| 359 |
return mcrypt_generic($this->$keyStream, $text); |
| 360 |
} |
| 361 |
|
| 362 |
if ($this->encryptStream === false) { |
| 363 |
$this->setKey($this->key); |
| 364 |
} |
| 365 |
|
| 366 |
switch ($mode) { |
| 367 |
case CRYPT_RC4_ENCRYPT: |
| 368 |
$keyStream = $this->encryptStream; |
| 369 |
list($i, $j) = $this->encryptIndex; |
| 370 |
break; |
| 371 |
case CRYPT_RC4_DECRYPT: |
| 372 |
$keyStream = $this->decryptStream; |
| 373 |
list($i, $j) = $this->decryptIndex; |
| 374 |
} |
| 375 |
|
| 376 |
$newText = ''; |
| 377 |
for ($k = 0; $k < strlen($text); $k++) { |
| 378 |
$i = ($i + 1) & 255; |
| 379 |
$j = ($j + $keyStream[$i]) & 255; |
| 380 |
$temp = $keyStream[$i]; |
| 381 |
$keyStream[$i] = $keyStream[$j]; |
| 382 |
$keyStream[$j] = $temp; |
| 383 |
$temp = $keyStream[($keyStream[$i] + $keyStream[$j]) & 255]; |
| 384 |
$newText.= chr(ord($text[$k]) ^ $temp); |
| 385 |
} |
| 386 |
|
| 387 |
if ($this->continuousBuffer) { |
| 388 |
switch ($mode) { |
| 389 |
case CRYPT_RC4_ENCRYPT: |
| 390 |
$this->encryptStream = $keyStream; |
| 391 |
$this->encryptIndex = array($i, $j); |
| 392 |
break; |
| 393 |
case CRYPT_RC4_DECRYPT: |
| 394 |
$this->decryptStream = $keyStream; |
| 395 |
$this->decryptIndex = array($i, $j); |
| 396 |
} |
| 397 |
} |
| 398 |
|
| 399 |
return $newText; |
| 400 |
} |
| 401 |
|
| 402 |
/** |
| 403 |
* Treat consecutive "packets" as if they are a continuous buffer. |
| 404 |
* |
| 405 |
* Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets |
| 406 |
* will yield different outputs: |
| 407 |
* |
| 408 |
* <code> |
| 409 |
* echo $rc4->encrypt(substr($plaintext, 0, 8)); |
| 410 |
* echo $rc4->encrypt(substr($plaintext, 8, 8)); |
| 411 |
* </code> |
| 412 |
* <code> |
| 413 |
* echo $rc4->encrypt($plaintext); |
| 414 |
* </code> |
| 415 |
* |
| 416 |
* The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates |
| 417 |
* another, as demonstrated with the following: |
| 418 |
* |
| 419 |
* <code> |
| 420 |
* $rc4->encrypt(substr($plaintext, 0, 8)); |
| 421 |
* echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8))); |
| 422 |
* </code> |
| 423 |
* <code> |
| 424 |
* echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8))); |
| 425 |
* </code> |
| 426 |
* |
| 427 |
* With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different |
| 428 |
* outputs. The reason is due to the fact that the initialization vector's change after every encryption / |
| 429 |
* decryption round when the continuous buffer is enabled. When it's disabled, they remain constant. |
| 430 |
* |
| 431 |
* Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each |
| 432 |
* encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that |
| 433 |
* continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them), |
| 434 |
* however, they are also less intuitive and more likely to cause you problems. |
| 435 |
* |
| 436 |
* @see Crypt_RC4::disableContinuousBuffer() |
| 437 |
* @access public |
| 438 |
*/ |
| 439 |
function enableContinuousBuffer() |
| 440 |
{ |
| 441 |
if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) { |
| 442 |
mcrypt_generic_init($this->encryptStream, $this->key, ''); |
| 443 |
mcrypt_generic_init($this->decryptStream, $this->key, ''); |
| 444 |
} |
| 445 |
|
| 446 |
$this->continuousBuffer = true; |
| 447 |
} |
| 448 |
|
| 449 |
/** |
| 450 |
* Treat consecutive packets as if they are a discontinuous buffer. |
| 451 |
* |
| 452 |
* The default behavior. |
| 453 |
* |
| 454 |
* @see Crypt_RC4::enableContinuousBuffer() |
| 455 |
* @access public |
| 456 |
*/ |
| 457 |
function disableContinuousBuffer() |
| 458 |
{ |
| 459 |
if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_INTERNAL ) { |
| 460 |
$this->encryptIndex = $this->decryptIndex = array(0, 0); |
| 461 |
$this->encryptStream = $this->decryptStream = false; |
| 462 |
} |
| 463 |
|
| 464 |
$this->continuousBuffer = false; |
| 465 |
} |
| 466 |
|
| 467 |
/** |
| 468 |
* Dummy function. |
| 469 |
* |
| 470 |
* Since RC4 is a stream cipher and not a block cipher, no padding is necessary. The only reason this function is |
| 471 |
* included is so that you can switch between a block cipher and a stream cipher transparently. |
| 472 |
* |
| 473 |
* @see Crypt_RC4::disablePadding() |
| 474 |
* @access public |
| 475 |
*/ |
| 476 |
function enablePadding() |
| 477 |
{ |
| 478 |
} |
| 479 |
|
| 480 |
/** |
| 481 |
* Dummy function. |
| 482 |
* |
| 483 |
* @see Crypt_RC4::enablePadding() |
| 484 |
* @access public |
| 485 |
*/ |
| 486 |
function disablePadding() |
| 487 |
{ |
| 488 |
} |
| 489 |
} |
| 490 |
|
| 491 |
// vim: ts=4:sw=4:et: |
| 492 |
// vim6: fdl=1: |
| 493 |
|
