421 lines
15 KiB
PHP
421 lines
15 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 AES.
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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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* If {@link Crypt_AES::setKeyLength() setKeyLength()} isn't called, it'll be calculated from
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* {@link Crypt_AES::setKey() setKey()}. ie. if the key is 128-bits, the key length will be 128-bits. If it's 136-bits
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* it'll be null-padded to 160-bits and 160 bits will be the key length until {@link Crypt_Rijndael::setKey() setKey()}
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* is called, again, at which point, it'll be recalculated.
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*
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* Since Crypt_AES extends Crypt_Rijndael, some functions are available to be called that, in the context of AES, don't
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* make a whole lot of sense. {@link Crypt_AES::setBlockLength() setBlockLength()}, for instance. Calling that function,
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* however possible, won't do anything (AES has a fixed block length whereas Rijndael has a variable one).
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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/AES.php');
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*
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* $aes = new Crypt_AES();
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*
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* $aes->setKey('abcdefghijklmnop');
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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 $aes->decrypt($aes->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_AES
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* @author Jim Wigginton <terrafrost@php.net>
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* @copyright MMVIII Jim Wigginton
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* @license http://www.gnu.org/licenses/lgpl.txt
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* @version $Id: AES.php,v 1.5 2009/11/23 19:06:06 terrafrost Exp $
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* @link http://phpseclib.sourceforge.net
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*/
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/**
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* Include Crypt_Rijndael
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*/
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require_once 'Rijndael.php';
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/**#@+
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* @access public
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* @see Crypt_AES::encrypt()
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* @see Crypt_AES::decrypt()
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*/
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/**
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* Encrypt / decrypt using the Electronic Code Book mode.
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*
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* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Electronic_codebook_.28ECB.29
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*/
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define('CRYPT_AES_MODE_ECB', 1);
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/**
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* Encrypt / decrypt using the Code Book Chaining mode.
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*
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* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Cipher-block_chaining_.28CBC.29
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*/
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define('CRYPT_AES_MODE_CBC', 2);
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/**#@-*/
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/**#@+
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* @access private
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* @see Crypt_AES::Crypt_AES()
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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_AES_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_AES_MODE_MCRYPT', 2);
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/**#@-*/
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/**
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* Pure-PHP implementation of AES.
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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_AES
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*/
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class Crypt_AES extends Crypt_Rijndael {
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/**
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* MCrypt parameters
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*
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* @see Crypt_AES::setMCrypt()
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* @var Array
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* @access private
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*/
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var $mcrypt = array('', '');
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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_AES_MODE_ECB or CRYPT_AES_MODE_CBC. If not explictly set, CRYPT_AES_MODE_CBC will be used.
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*
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* @param optional Integer $mode
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* @return Crypt_AES
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* @access public
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*/
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function Crypt_AES($mode = CRYPT_AES_MODE_CBC)
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{
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if ( !defined('CRYPT_AES_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 aes 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_AES_MODE', CRYPT_AES_MODE_MCRYPT);
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break;
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default:
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define('CRYPT_AES_MODE', CRYPT_AES_MODE_INTERNAL);
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}
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}
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switch ( CRYPT_AES_MODE ) {
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case CRYPT_AES_MODE_MCRYPT:
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switch ($mode) {
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case CRYPT_AES_MODE_ECB:
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$this->mode = MCRYPT_MODE_ECB;
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break;
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case CRYPT_AES_MODE_CBC:
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default:
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$this->mode = MCRYPT_MODE_CBC;
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}
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break;
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default:
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switch ($mode) {
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case CRYPT_AES_MODE_ECB:
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$this->mode = CRYPT_RIJNDAEL_MODE_ECB;
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break;
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case CRYPT_AES_MODE_CBC:
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default:
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$this->mode = CRYPT_RIJNDAEL_MODE_CBC;
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}
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}
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if (CRYPT_AES_MODE == CRYPT_AES_MODE_INTERNAL) {
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parent::Crypt_Rijndael($this->mode);
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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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* Since Crypt_AES extends Crypt_Rijndael, this function is, technically, available, but it doesn't do anything.
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*
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* @access public
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* @param Integer $length
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*/
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function setBlockLength($length)
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{
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return;
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}
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/**
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* Encrypts a message.
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*
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* $plaintext will be padded with up to 16 additional bytes. Other AES implementations may or may not pad in the
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* same manner. Other common approaches to padding and the reasons why it's necessary are discussed in the following
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* URL:
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*
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* {@link http://www.di-mgt.com.au/cryptopad.html http://www.di-mgt.com.au/cryptopad.html}
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*
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* An alternative to padding is to, separately, send the length of the file. This is what SSH, in fact, does.
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* strlen($plaintext) will still need to be a multiple of 16, however, arbitrary values can be added to make it that
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* length.
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*
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* @see Crypt_AES::decrypt()
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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 ( CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT ) {
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$this->_mcryptSetup();
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$plaintext = $this->_pad($plaintext);
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$td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, $this->mcrypt[0], $this->mode, $this->mcrypt[1]);
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mcrypt_generic_init($td, $this->key, $this->encryptIV);
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$ciphertext = mcrypt_generic($td, $plaintext);
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mcrypt_generic_deinit($td);
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mcrypt_module_close($td);
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if ($this->continuousBuffer) {
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$this->encryptIV = substr($ciphertext, -16);
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}
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return $ciphertext;
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}
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return parent::encrypt($plaintext);
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}
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/**
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* Decrypts a message.
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*
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* If strlen($ciphertext) is not a multiple of 16, null bytes will be added to the end of the string until it is.
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*
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* @see Crypt_AES::encrypt()
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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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// we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic :
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// "The data is padded with "\0" to make sure the length of the data is n * blocksize."
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$ciphertext = str_pad($ciphertext, (strlen($ciphertext) + 15) & 0xFFFFFFF0, chr(0));
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if ( CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT ) {
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$this->_mcryptSetup();
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$td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, $this->mcrypt[0], $this->mode, $this->mcrypt[1]);
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mcrypt_generic_init($td, $this->key, $this->decryptIV);
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$plaintext = mdecrypt_generic($td, $ciphertext);
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mcrypt_generic_deinit($td);
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mcrypt_module_close($td);
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if ($this->continuousBuffer) {
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$this->decryptIV = substr($ciphertext, -16);
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}
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return $this->_unpad($plaintext);
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}
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return parent::decrypt($ciphertext);
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}
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/**
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* Sets MCrypt parameters. (optional)
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*
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* If MCrypt is being used, empty strings will be used, unless otherwise specified.
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*
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* @link http://php.net/function.mcrypt-module-open#function.mcrypt-module-open
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* @access public
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* @param optional Integer $algorithm_directory
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* @param optional Integer $mode_directory
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*/
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function setMCrypt($algorithm_directory = '', $mode_directory = '')
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{
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$this->mcrypt = array($algorithm_directory, $mode_directory);
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}
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/**
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* Setup mcrypt
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*
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* Validates all the variables.
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*
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* @access private
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*/
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function _mcryptSetup()
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{
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if (!$this->changed) {
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return;
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}
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if (!$this->explicit_key_length) {
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// this just copied from Crypt_Rijndael::_setup()
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$length = strlen($this->key) >> 2;
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if ($length > 8) {
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$length = 8;
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} else if ($length < 4) {
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$length = 4;
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}
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$this->Nk = $length;
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$this->key_size = $length << 2;
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}
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switch ($this->Nk) {
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case 4: // 128
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$this->key_size = 16;
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break;
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case 5: // 160
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case 6: // 192
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$this->key_size = 24;
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break;
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case 7: // 224
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case 8: // 256
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$this->key_size = 32;
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}
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$this->key = substr($this->key, 0, $this->key_size);
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$this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($this->iv, 0, 16), 16, chr(0));
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$this->changed = false;
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}
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/**
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* Encrypts a block
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*
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* Optimized over Crypt_Rijndael's implementation by means of loop unrolling.
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*
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* @see Crypt_Rijndael::_encryptBlock()
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* @access private
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* @param String $in
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* @return String
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*/
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function _encryptBlock($in)
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{
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$state = unpack('N*word', $in);
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// addRoundKey and reindex $state
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$state = array(
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$state['word1'] ^ $this->w[0][0],
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$state['word2'] ^ $this->w[0][1],
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$state['word3'] ^ $this->w[0][2],
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$state['word4'] ^ $this->w[0][3]
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);
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// shiftRows + subWord + mixColumns + addRoundKey
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// we could loop unroll this and use if statements to do more rounds as necessary, but, in my tests, that yields
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// only a marginal improvement. since that also, imho, hinders the readability of the code, i've opted not to do it.
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for ($round = 1; $round < $this->Nr; $round++) {
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$state = array(
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$this->t0[$state[0] & 0xFF000000] ^ $this->t1[$state[1] & 0x00FF0000] ^ $this->t2[$state[2] & 0x0000FF00] ^ $this->t3[$state[3] & 0x000000FF] ^ $this->w[$round][0],
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$this->t0[$state[1] & 0xFF000000] ^ $this->t1[$state[2] & 0x00FF0000] ^ $this->t2[$state[3] & 0x0000FF00] ^ $this->t3[$state[0] & 0x000000FF] ^ $this->w[$round][1],
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$this->t0[$state[2] & 0xFF000000] ^ $this->t1[$state[3] & 0x00FF0000] ^ $this->t2[$state[0] & 0x0000FF00] ^ $this->t3[$state[1] & 0x000000FF] ^ $this->w[$round][2],
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$this->t0[$state[3] & 0xFF000000] ^ $this->t1[$state[0] & 0x00FF0000] ^ $this->t2[$state[1] & 0x0000FF00] ^ $this->t3[$state[2] & 0x000000FF] ^ $this->w[$round][3]
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);
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}
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// subWord
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$state = array(
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$this->_subWord($state[0]),
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$this->_subWord($state[1]),
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$this->_subWord($state[2]),
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$this->_subWord($state[3])
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);
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// shiftRows + addRoundKey
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$state = array(
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($state[0] & 0xFF000000) ^ ($state[1] & 0x00FF0000) ^ ($state[2] & 0x0000FF00) ^ ($state[3] & 0x000000FF) ^ $this->w[$this->Nr][0],
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($state[1] & 0xFF000000) ^ ($state[2] & 0x00FF0000) ^ ($state[3] & 0x0000FF00) ^ ($state[0] & 0x000000FF) ^ $this->w[$this->Nr][1],
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($state[2] & 0xFF000000) ^ ($state[3] & 0x00FF0000) ^ ($state[0] & 0x0000FF00) ^ ($state[1] & 0x000000FF) ^ $this->w[$this->Nr][2],
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($state[3] & 0xFF000000) ^ ($state[0] & 0x00FF0000) ^ ($state[1] & 0x0000FF00) ^ ($state[2] & 0x000000FF) ^ $this->w[$this->Nr][3]
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);
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return pack('N*', $state[0], $state[1], $state[2], $state[3]);
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}
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/**
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* Decrypts a block
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*
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* Optimized over Crypt_Rijndael's implementation by means of loop unrolling.
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*
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* @see Crypt_Rijndael::_decryptBlock()
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* @access private
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* @param String $in
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* @return String
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*/
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function _decryptBlock($in)
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{
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$state = unpack('N*word', $in);
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// addRoundKey and reindex $state
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$state = array(
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$state['word1'] ^ $this->dw[$this->Nr][0],
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$state['word2'] ^ $this->dw[$this->Nr][1],
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$state['word3'] ^ $this->dw[$this->Nr][2],
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$state['word4'] ^ $this->dw[$this->Nr][3]
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);
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// invShiftRows + invSubBytes + invMixColumns + addRoundKey
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for ($round = $this->Nr - 1; $round > 0; $round--) {
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$state = array(
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$this->dt0[$state[0] & 0xFF000000] ^ $this->dt1[$state[3] & 0x00FF0000] ^ $this->dt2[$state[2] & 0x0000FF00] ^ $this->dt3[$state[1] & 0x000000FF] ^ $this->dw[$round][0],
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$this->dt0[$state[1] & 0xFF000000] ^ $this->dt1[$state[0] & 0x00FF0000] ^ $this->dt2[$state[3] & 0x0000FF00] ^ $this->dt3[$state[2] & 0x000000FF] ^ $this->dw[$round][1],
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$this->dt0[$state[2] & 0xFF000000] ^ $this->dt1[$state[1] & 0x00FF0000] ^ $this->dt2[$state[0] & 0x0000FF00] ^ $this->dt3[$state[3] & 0x000000FF] ^ $this->dw[$round][2],
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$this->dt0[$state[3] & 0xFF000000] ^ $this->dt1[$state[2] & 0x00FF0000] ^ $this->dt2[$state[1] & 0x0000FF00] ^ $this->dt3[$state[0] & 0x000000FF] ^ $this->dw[$round][3]
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);
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}
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// invShiftRows + invSubWord + addRoundKey
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$state = array(
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$this->_invSubWord(($state[0] & 0xFF000000) ^ ($state[3] & 0x00FF0000) ^ ($state[2] & 0x0000FF00) ^ ($state[1] & 0x000000FF)) ^ $this->dw[0][0],
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$this->_invSubWord(($state[1] & 0xFF000000) ^ ($state[0] & 0x00FF0000) ^ ($state[3] & 0x0000FF00) ^ ($state[2] & 0x000000FF)) ^ $this->dw[0][1],
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$this->_invSubWord(($state[2] & 0xFF000000) ^ ($state[1] & 0x00FF0000) ^ ($state[0] & 0x0000FF00) ^ ($state[3] & 0x000000FF)) ^ $this->dw[0][2],
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$this->_invSubWord(($state[3] & 0xFF000000) ^ ($state[2] & 0x00FF0000) ^ ($state[1] & 0x0000FF00) ^ ($state[0] & 0x000000FF)) ^ $this->dw[0][3]
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);
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return pack('N*', $state[0], $state[1], $state[2], $state[3]);
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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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