Git-Center/Crypt/AES.php
2013-10-02 14:47:25 +02:00

541 lines
19 KiB
PHP
Executable File

<?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: Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* @category Crypt
* @package Crypt_AES
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVIII Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
*/
/**
* Include Crypt_Rijndael
*/
if (!class_exists('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);
/**
* Encrypt / decrypt using the Cipher Feedback mode.
*
* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Cipher_feedback_.28CFB.29
*/
define('CRYPT_AES_MODE_CFB', 3);
/**
* Encrypt / decrypt using the Cipher Feedback mode.
*
* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Output_feedback_.28OFB.29
*/
define('CRYPT_AES_MODE_OFB', 4);
/**#@-*/
/**#@+
* @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;
/**
* mcrypt resource for CFB mode
*
* @see Crypt_AES::encrypt()
* @see Crypt_AES::decrypt()
* @var String
* @access private
*/
var $ecb;
/**
* 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') && in_array('rijndael-128', mcrypt_list_algorithms()):
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->paddable = true;
$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_CFB:
$this->mode = 'ncfb';
break;
case CRYPT_AES_MODE_OFB:
$this->mode = MCRYPT_MODE_NOFB;
break;
case CRYPT_AES_MODE_CBC:
default:
$this->paddable = true;
$this->mode = MCRYPT_MODE_CBC;
}
break;
default:
switch ($mode) {
case CRYPT_AES_MODE_ECB:
$this->paddable = true;
$this->mode = CRYPT_RIJNDAEL_MODE_ECB;
break;
case CRYPT_AES_MODE_CTR:
$this->mode = CRYPT_RIJNDAEL_MODE_CTR;
break;
case CRYPT_AES_MODE_CFB:
$this->mode = CRYPT_RIJNDAEL_MODE_CFB;
break;
case CRYPT_AES_MODE_OFB:
$this->mode = CRYPT_RIJNDAEL_MODE_OFB;
break;
case CRYPT_AES_MODE_CBC:
default:
$this->paddable = true;
$this->mode = CRYPT_RIJNDAEL_MODE_CBC;
}
}
if (CRYPT_AES_MODE == CRYPT_AES_MODE_INTERNAL) {
parent::Crypt_Rijndael($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;
}
/**
* Sets the initialization vector. (optional)
*
* SetIV is not required when CRYPT_RIJNDAEL_MODE_ECB is being used. If not explictly set, it'll be assumed
* to be all zero's.
*
* @access public
* @param String $iv
*/
function setIV($iv)
{
parent::setIV($iv);
if ( CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT ) {
$this->changed = true;
}
}
/**
* 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 ) {
$this->_mcryptSetup();
// re: http://phpseclib.sourceforge.net/cfb-demo.phps
// using mcrypt's default handing of CFB the above would output two different things. using phpseclib's
// rewritten CFB implementation the above outputs the same thing twice.
if ($this->mode == 'ncfb' && $this->continuousBuffer) {
$iv = &$this->encryptIV;
$pos = &$this->enbuffer['pos'];
$len = strlen($plaintext);
$ciphertext = '';
$i = 0;
if ($pos) {
$orig_pos = $pos;
$max = 16 - $pos;
if ($len >= $max) {
$i = $max;
$len-= $max;
$pos = 0;
} else {
$i = $len;
$pos+= $len;
$len = 0;
}
$ciphertext = substr($iv, $orig_pos) ^ $plaintext;
$iv = substr_replace($iv, $ciphertext, $orig_pos, $i);
$this->enbuffer['enmcrypt_init'] = true;
}
if ($len >= 16) {
if ($this->enbuffer['enmcrypt_init'] === false || $len > 280) {
if ($this->enbuffer['enmcrypt_init'] === true) {
mcrypt_generic_init($this->enmcrypt, $this->key, $iv);
$this->enbuffer['enmcrypt_init'] = false;
}
$ciphertext.= mcrypt_generic($this->enmcrypt, substr($plaintext, $i, $len - $len % 16));
$iv = substr($ciphertext, -16);
$len%= 16;
} else {
while ($len >= 16) {
$iv = mcrypt_generic($this->ecb, $iv) ^ substr($plaintext, $i, 16);
$ciphertext.= $iv;
$len-= 16;
$i+= 16;
}
}
}
if ($len) {
$iv = mcrypt_generic($this->ecb, $iv);
$block = $iv ^ substr($plaintext, -$len);
$iv = substr_replace($iv, $block, 0, $len);
$ciphertext.= $block;
$pos = $len;
}
return $ciphertext;
}
if ($this->paddable) {
$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 == 'ncfb' && $this->continuousBuffer) {
$iv = &$this->decryptIV;
$pos = &$this->debuffer['pos'];
$len = strlen($ciphertext);
$plaintext = '';
$i = 0;
if ($pos) {
$orig_pos = $pos;
$max = 16 - $pos;
if ($len >= $max) {
$i = $max;
$len-= $max;
$pos = 0;
} else {
$i = $len;
$pos+= $len;
$len = 0;
}
// ie. $i = min($max, $len), $len-= $i, $pos+= $i, $pos%= $blocksize
$plaintext = substr($iv, $orig_pos) ^ $ciphertext;
$iv = substr_replace($iv, substr($ciphertext, 0, $i), $orig_pos, $i);
}
if ($len >= 16) {
$cb = substr($ciphertext, $i, $len - $len % 16);
$plaintext.= mcrypt_generic($this->ecb, $iv . $cb) ^ $cb;
$iv = substr($cb, -16);
$len%= 16;
}
if ($len) {
$iv = mcrypt_generic($this->ecb, $iv);
$plaintext.= $iv ^ substr($ciphertext, -$len);
$iv = substr_replace($iv, substr($ciphertext, -$len), 0, $len);
$pos = $len;
}
return $plaintext;
}
if ($this->paddable) {
// 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->paddable ? $this->_unpad($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;
}
$this->key = str_pad(substr($this->key, 0, $this->key_size), $this->key_size, chr(0));
$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, '', $mode, '');
if ($mode == 'ncfb') {
$this->ecb = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_ECB, '');
}
} // else should mcrypt_generic_deinit be called?
mcrypt_generic_init($this->demcrypt, $this->key, $this->iv);
mcrypt_generic_init($this->enmcrypt, $this->key, $this->iv);
if ($this->mode == 'ncfb') {
mcrypt_generic_init($this->ecb, $this->key, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
}
$this->changed = false;
}
/**
* Treat consecutive "packets" as if they are a continuous buffer.
*
* The default behavior.
*
* @see Crypt_Rijndael::disableContinuousBuffer()
* @access public
*/
function enableContinuousBuffer()
{
parent::enableContinuousBuffer();
if (CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT) {
$this->enbuffer['enmcrypt_init'] = true;
$this->debuffer['demcrypt_init'] = true;
}
}
/**
* Treat consecutive packets as if they are a discontinuous buffer.
*
* The default behavior.
*
* @see Crypt_Rijndael::enableContinuousBuffer()
* @access public
*/
function disableContinuousBuffer()
{
parent::disableContinuousBuffer();
if (CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT) {
mcrypt_generic_init($this->enmcrypt, $this->key, $this->iv);
mcrypt_generic_init($this->demcrypt, $this->key, $this->iv);
}
}
}
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// vim6: fdl=1: