<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/**
* Pure-PHP implementation of AES.
*
* Uses mcrypt, if available, and an internal implementation, otherwise.
*
* PHP versions 4 and 5
*
* If {@link Crypt_AES::setKeyLength() setKeyLength()} isn't called, it'll be calculated from
* {@link Crypt_AES::setKey() setKey()}. ie. if the key is 128-bits, the key length will be 128-bits. If it's 136-bits
* it'll be null-padded to 160-bits and 160 bits will be the key length until {@link Crypt_Rijndael::setKey() setKey()}
* is called, again, at which point, it'll be recalculated.
*
* Since Crypt_AES extends Crypt_Rijndael, some functions are available to be called that, in the context of AES, don't
* make a whole lot of sense. {@link Crypt_AES::setBlockLength() setBlockLength()}, for instance. Calling that function,
* however possible, won't do anything (AES has a fixed block length whereas Rijndael has a variable one).
*
* Here's a short example of how to use this library:
* <code>
* <?php
* include('Crypt/AES.php');
*
* $aes = new Crypt_AES();
*
* $aes->setKey('abcdefghijklmnop');
*
* $size = 10 * 1024;
* $plaintext = '';
* for ($i = 0; $i < $size; $i++) {
* $plaintext.= 'a';
* }
*
* echo $aes->decrypt($aes->encrypt($plaintext));
* ?>
* </code>
*
* LICENSE: This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
* @category Crypt
* @package Crypt_AES
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVIII Jim Wigginton
* @license http://www.gnu.org/licenses/lgpl.txt
* @version $Id: AES.php,v 1.7 2010/02/09 06:10:25 terrafrost Exp $
* @link http://phpseclib.sourceforge.net
*/
/**
* Include Crypt_Rijndael
*/
require_once 'Rijndael.php';
/**#@+
* @access public
* @see Crypt_AES::encrypt()
* @see Crypt_AES::decrypt()
*/
/**
* Encrypt / decrypt using the Counter mode.
*
* Set to -1 since that's what Crypt/Random.php uses to index the CTR mode.
*
* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Counter_.28CTR.29
*/
define('CRYPT_AES_MODE_CTR', -1);
/**
* Encrypt / decrypt using the Electronic Code Book mode.
*
* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Electronic_codebook_.28ECB.29
*/
define('CRYPT_AES_MODE_ECB', 1);
/**
* Encrypt / decrypt using the Code Book Chaining mode.
*
* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Cipher-block_chaining_.28CBC.29
*/
define('CRYPT_AES_MODE_CBC', 2);
/**#@-*/
/**#@+
* @access private
* @see Crypt_AES::Crypt_AES()
*/
/**
* Toggles the internal implementation
*/
define('CRYPT_AES_MODE_INTERNAL', 1);
/**
* Toggles the mcrypt implementation
*/
define('CRYPT_AES_MODE_MCRYPT', 2);
/**#@-*/
/**
* Pure-PHP implementation of AES.
*
* @author Jim Wigginton <terrafrost@php.net>
* @version 0.1.0
* @access public
* @package Crypt_AES
*/
class Crypt_AES extends Crypt_Rijndael {
/**
* mcrypt resource for encryption
*
* The mcrypt resource can be recreated every time something needs to be created or it can be created just once.
* Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.
*
* @see Crypt_AES::encrypt()
* @var String
* @access private
*/
var $enmcrypt;
/**
* mcrypt resource for decryption
*
* The mcrypt resource can be recreated every time something needs to be created or it can be created just once.
* Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode.
*
* @see Crypt_AES::decrypt()
* @var String
* @access private
*/
var $demcrypt;
/**
* Default Constructor.
*
* Determines whether or not the mcrypt extension should be used. $mode should only, at present, be
* CRYPT_AES_MODE_ECB or CRYPT_AES_MODE_CBC. If not explictly set, CRYPT_AES_MODE_CBC will be used.
*
* @param optional Integer $mode
* @return Crypt_AES
* @access public
*/
function Crypt_AES($mode = CRYPT_AES_MODE_CBC)
{
if ( !defined('CRYPT_AES_MODE') ) {
switch (true) {
case extension_loaded('mcrypt'):
// i'd check to see if aes was supported, by doing in_array('des', mcrypt_list_algorithms('')),
// but since that can be changed after the object has been created, there doesn't seem to be
// a lot of point...
define('CRYPT_AES_MODE', CRYPT_AES_MODE_MCRYPT);
break;
default:
define('CRYPT_AES_MODE', CRYPT_AES_MODE_INTERNAL);
}
}
switch ( CRYPT_AES_MODE ) {
case CRYPT_AES_MODE_MCRYPT:
switch ($mode) {
case CRYPT_AES_MODE_ECB:
$this->mode = MCRYPT_MODE_ECB;
break;
case CRYPT_AES_MODE_CTR:
// ctr doesn't have a constant associated with it even though it appears to be fairly widely
// supported. in lieu of knowing just how widely supported it is, i've, for now, opted not to
// include a compatibility layer. the layer has been implemented but, for now, is commented out.
$this->mode = 'ctr';
//$this->mode = in_array('ctr', mcrypt_list_modes()) ? 'ctr' : CRYPT_AES_MODE_CTR;
break;
case CRYPT_AES_MODE_CBC:
default:
$this->mode = MCRYPT_MODE_CBC;
}
break;
default:
switch ($mode) {
case CRYPT_AES_MODE_ECB:
$this->mode = CRYPT_RIJNDAEL_MODE_ECB;
break;
case CRYPT_AES_MODE_CTR:
$this->mode = CRYPT_RIJNDAEL_MODE_CTR;
break;
case CRYPT_AES_MODE_CBC:
default:
$this->mode = CRYPT_RIJNDAEL_MODE_CBC;
}
}
if (CRYPT_AES_MODE == CRYPT_AES_MODE_INTERNAL) {
parent::Crypt_Rijndael($this->mode);
}
}
/**
* Dummy function
*
* Since Crypt_AES extends Crypt_Rijndael, this function is, technically, available, but it doesn't do anything.
*
* @access public
* @param Integer $length
*/
function setBlockLength($length)
{
return;
}
/**
* Encrypts a message.
*
* $plaintext will be padded with up to 16 additional bytes. Other AES implementations may or may not pad in the
* same manner. Other common approaches to padding and the reasons why it's necessary are discussed in the following
* URL:
*
* {@link http://www.di-mgt.com.au/cryptopad.html http://www.di-mgt.com.au/cryptopad.html}
*
* An alternative to padding is to, separately, send the length of the file. This is what SSH, in fact, does.
* strlen($plaintext) will still need to be a multiple of 16, however, arbitrary values can be added to make it that
* length.
*
* @see Crypt_AES::decrypt()
* @access public
* @param String $plaintext
*/
function encrypt($plaintext)
{
if ( CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT ) {
$this->_mcryptSetup();
/*
if ($this->mode == CRYPT_AES_MODE_CTR) {
$iv = $this->encryptIV;
$xor = mcrypt_generic($this->enmcrypt, $this->_generate_xor(strlen($plaintext), $iv));
$ciphertext = $plaintext ^ $xor;
if ($this->continuousBuffer) {
$this->encryptIV = $iv;
}
return $ciphertext;
}
*/
if ($this->mode != 'ctr') {
$plaintext = $this->_pad($plaintext);
}
$ciphertext = mcrypt_generic($this->enmcrypt, $plaintext);
if (!$this->continuousBuffer) {
mcrypt_generic_init($this->enmcrypt, $this->key, $this->iv);
}
return $ciphertext;
}
return parent::encrypt($plaintext);
}
/**
* Decrypts a message.
*
* If strlen($ciphertext) is not a multiple of 16, null bytes will be added to the end of the string until it is.
*
* @see Crypt_AES::encrypt()
* @access public
* @param String $ciphertext
*/
function decrypt($ciphertext)
{
if ( CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT ) {
$this->_mcryptSetup();
/*
if ($this->mode == CRYPT_AES_MODE_CTR) {
$iv = $this->decryptIV;
$xor = mcrypt_generic($this->enmcrypt, $this->_generate_xor(strlen($ciphertext), $iv));
$plaintext = $ciphertext ^ $xor;
if ($this->continuousBuffer) {
$this->decryptIV = $iv;
}
return $plaintext;
}
*/
if ($this->mode != 'ctr') {
// we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic :
// "The data is padded with "\0" to make sure the length of the data is n * blocksize."
$ciphertext = str_pad($ciphertext, (strlen($ciphertext) + 15) & 0xFFFFFFF0, chr(0));
}
$plaintext = mdecrypt_generic($this->demcrypt, $ciphertext);
if (!$this->continuousBuffer) {
mcrypt_generic_init($this->demcrypt, $this->key, $this->iv);
}
return $this->mode != 'ctr' ? $this->_unpad($plaintext) : $plaintext;
}
return parent::decrypt($ciphertext);
}
/**
* Setup mcrypt
*
* Validates all the variables.
*
* @access private
*/
function _mcryptSetup()
{
if (!$this->changed) {
return;
}
if (!$this->explicit_key_length) {
// this just copied from Crypt_Rijndael::_setup()
$length = strlen($this->key) >> 2;
if ($length > 8) {
$length = 8;
} else if ($length < 4) {
$length = 4;
}
$this->Nk = $length;
$this->key_size = $length << 2;
}
switch ($this->Nk) {
case 4: // 128
$this->key_size = 16;
break;
case 5: // 160
case 6: // 192
$this->key_size = 24;
break;
case 7: // 224
case 8: // 256
$this->key_size = 32;
}
$this->key = substr($this->key, 0, $this->key_size);
$this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($this->iv, 0, 16), 16, chr(0));
if (!isset($this->enmcrypt)) {
$mode = $this->mode;
//$mode = $this->mode == CRYPT_AES_MODE_CTR ? MCRYPT_MODE_ECB : $this->mode;
$this->demcrypt = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', $mode, '');
$this->enmcrypt = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', $mode, '');
} // else should mcrypt_generic_deinit be called?
mcrypt_generic_init($this->demcrypt, $this->key, $this->iv);
mcrypt_generic_init($this->enmcrypt, $this->key, $this->iv);
$this->changed = false;
}
/**
* Encrypts a block
*
* Optimized over Crypt_Rijndael's implementation by means of loop unrolling.
*
* @see Crypt_Rijndael::_encryptBlock()
* @access private
* @param String $in
* @return String
*/
function _encryptBlock($in)
{
$state = unpack('N*word', $in);
$Nr = $this->Nr;
$w = $this->w;
$t0 = $this->t0;
$t1 = $this->t1;
$t2 = $this->t2;
$t3 = $this->t3;
// addRoundKey and reindex $state
$state = array(
$state['word1'] ^ $w[0][0],
$state['word2'] ^ $w[0][1],
$state['word3'] ^ $w[0][2],
$state['word4'] ^ $w[0][3]
);
// shiftRows + subWord + mixColumns + addRoundKey
// we could loop unroll this and use if statements to do more rounds as necessary, but, in my tests, that yields
// only a marginal improvement. since that also, imho, hinders the readability of the code, i've opted not to do it.
for ($round = 1; $round < $this->Nr; $round++) {
$state = array(
$t0[$state[0] & 0xFF000000] ^ $t1[$state[1] & 0x00FF0000] ^ $t2[$state[2] & 0x0000FF00] ^ $t3[$state[3] & 0x000000FF] ^ $w[$round][0],
$t0[$state[1] & 0xFF000000] ^ $t1[$state[2] & 0x00FF0000] ^ $t2[$state[3] & 0x0000FF00] ^ $t3[$state[0] & 0x000000FF] ^ $w[$round][1],
$t0[$state[2] & 0xFF000000] ^ $t1[$state[3] & 0x00FF0000] ^ $t2[$state[0] & 0x0000FF00] ^ $t3[$state[1] & 0x000000FF] ^ $w[$round][2],
$t0[$state[3] & 0xFF000000] ^ $t1[$state[0] & 0x00FF0000] ^ $t2[$state[1] & 0x0000FF00] ^ $t3[$state[2] & 0x000000FF] ^ $w[$round][3]
);
}
// subWord
$state = array(
$this->_subWord($state[0]),
$this->_subWord($state[1]),
$this->_subWord($state[2]),
$this->_subWord($state[3])
);
// shiftRows + addRoundKey
$state = array(
($state[0] & 0xFF000000) ^ ($state[1] & 0x00FF0000) ^ ($state[2] & 0x0000FF00) ^ ($state[3] & 0x000000FF) ^ $this->w[$this->Nr][0],
($state[1] & 0xFF000000) ^ ($state[2] & 0x00FF0000) ^ ($state[3] & 0x0000FF00) ^ ($state[0] & 0x000000FF) ^ $this->w[$this->Nr][1],
($state[2] & 0xFF000000) ^ ($state[3] & 0x00FF0000) ^ ($state[0] & 0x0000FF00) ^ ($state[1] & 0x000000FF) ^ $this->w[$this->Nr][2],
($state[3] & 0xFF000000) ^ ($state[0] & 0x00FF0000) ^ ($state[1] & 0x0000FF00) ^ ($state[2] & 0x000000FF) ^ $this->w[$this->Nr][3]
);
return pack('N*', $state[0], $state[1], $state[2], $state[3]);
}
/**
* Decrypts a block
*
* Optimized over Crypt_Rijndael's implementation by means of loop unrolling.
*
* @see Crypt_Rijndael::_decryptBlock()
* @access private
* @param String $in
* @return String
*/
function _decryptBlock($in)
{
$state = unpack('N*word', $in);
$Nr = $this->Nr;
$dw = $this->dw;
$dt0 = $this->dt0;
$dt1 = $this->dt1;
$dt2 = $this->dt2;
$dt3 = $this->dt3;
// addRoundKey and reindex $state
$state = array(
$state['word1'] ^ $dw[$this->Nr][0],
$state['word2'] ^ $dw[$this->Nr][1],
$state['word3'] ^ $dw[$this->Nr][2],
$state['word4'] ^ $dw[$this->Nr][3]
);
// invShiftRows + invSubBytes + invMixColumns + addRoundKey
for ($round = $this->Nr - 1; $round > 0; $round--) {
$state = array(
$dt0[$state[0] & 0xFF000000] ^ $dt1[$state[3] & 0x00FF0000] ^ $dt2[$state[2] & 0x0000FF00] ^ $dt3[$state[1] & 0x000000FF] ^ $dw[$round][0],
$dt0[$state[1] & 0xFF000000] ^ $dt1[$state[0] & 0x00FF0000] ^ $dt2[$state[3] & 0x0000FF00] ^ $dt3[$state[2] & 0x000000FF] ^ $dw[$round][1],
$dt0[$state[2] & 0xFF000000] ^ $dt1[$state[1] & 0x00FF0000] ^ $dt2[$state[0] & 0x0000FF00] ^ $dt3[$state[3] & 0x000000FF] ^ $dw[$round][2],
$dt0[$state[3] & 0xFF000000] ^ $dt1[$state[2] & 0x00FF0000] ^ $dt2[$state[1] & 0x0000FF00] ^ $dt3[$state[0] & 0x000000FF] ^ $dw[$round][3]
);
}
// invShiftRows + invSubWord + addRoundKey
$state = array(
$this->_invSubWord(($state[0] & 0xFF000000) ^ ($state[3] & 0x00FF0000) ^ ($state[2] & 0x0000FF00) ^ ($state[1] & 0x000000FF)) ^ $dw[0][0],
$this->_invSubWord(($state[1] & 0xFF000000) ^ ($state[0] & 0x00FF0000) ^ ($state[3] & 0x0000FF00) ^ ($state[2] & 0x000000FF)) ^ $dw[0][1],
$this->_invSubWord(($state[2] & 0xFF000000) ^ ($state[1] & 0x00FF0000) ^ ($state[0] & 0x0000FF00) ^ ($state[3] & 0x000000FF)) ^ $dw[0][2],
$this->_invSubWord(($state[3] & 0xFF000000) ^ ($state[2] & 0x00FF0000) ^ ($state[1] & 0x0000FF00) ^ ($state[0] & 0x000000FF)) ^ $dw[0][3]
);
return pack('N*', $state[0], $state[1], $state[2], $state[3]);
}
}
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