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<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/**
* Pure-PHP implementation of Triple DES.
*
* Uses mcrypt, if available, and an internal implementation, otherwise. Operates in the EDE3 mode (encrypt-decrypt-encrypt).
*
* PHP versions 4 and 5
*
* Here's a short example of how to use this library:
* <code>
* <?php
* include('Crypt/TripleDES.php');
*
* $des = new Crypt_TripleDES();
*
* $des->setKey('abcdefghijklmnopqrstuvwx');
*
* $size = 10 * 1024;
* $plaintext = '';
* for ($i = 0; $i < $size; $i++) {
* $plaintext.= 'a';
* }
*
* echo $des->decrypt($des->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_TripleDES
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVII Jim Wigginton
* @license http://www.gnu.org/licenses/lgpl.txt
* @version $Id: TripleDES.php,v 1.13 2010/02/26 03:40:25 terrafrost Exp $
* @link http://phpseclib.sourceforge.net
*/
/**
* Include Crypt_DES
*/
require_once 'DES.php';
/**
* Encrypt / decrypt using inner chaining
*
* Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (CRYPT_DES_MODE_CBC3).
*/
define('CRYPT_DES_MODE_3CBC', 3);
/**
* Encrypt / decrypt using outer chaining
*
* Outer chaining is used by SSH-2 and when the mode is set to CRYPT_DES_MODE_CBC.
*/
define('CRYPT_DES_MODE_CBC3', CRYPT_DES_MODE_CBC);
/**
* Pure-PHP implementation of Triple DES.
*
* @author Jim Wigginton <terrafrost@php.net>
* @version 0.1.0
* @access public
* @package Crypt_TerraDES
*/
class Crypt_TripleDES {
/**
* The Three Keys
*
* @see Crypt_TripleDES::setKey()
* @var String
* @access private
*/
var $key = "\0\0\0\0\0\0\0\0";
/**
* The Encryption Mode
*
* @see Crypt_TripleDES::Crypt_TripleDES()
* @var Integer
* @access private
*/
var $mode = CRYPT_DES_MODE_CBC;
/**
* Continuous Buffer status
*
* @see Crypt_TripleDES::enableContinuousBuffer()
* @var Boolean
* @access private
*/
var $continuousBuffer = false;
/**
* Padding status
*
* @see Crypt_TripleDES::enablePadding()
* @var Boolean
* @access private
*/
var $padding = true;
/**
* The Initialization Vector
*
* @see Crypt_TripleDES::setIV()
* @var String
* @access private
*/
var $iv = "\0\0\0\0\0\0\0\0";
/**
* A "sliding" Initialization Vector
*
* @see Crypt_TripleDES::enableContinuousBuffer()
* @var String
* @access private
*/
var $encryptIV = "\0\0\0\0\0\0\0\0";
/**
* A "sliding" Initialization Vector
*
* @see Crypt_TripleDES::enableContinuousBuffer()
* @var String
* @access private
*/
var $decryptIV = "\0\0\0\0\0\0\0\0";
/**
* The Crypt_DES objects
*
* @var Array
* @access private
*/
var $des;
/**
* 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;
/**
* Does the (en|de)mcrypt resource need to be (re)initialized?
*
* @see setKey()
* @see setIV()
* @var Boolean
* @access private
*/
var $changed = true;
/**
* Default Constructor.
*
* Determines whether or not the mcrypt extension should be used. $mode should only, at present, be
* CRYPT_DES_MODE_ECB or CRYPT_DES_MODE_CBC. If not explictly set, CRYPT_DES_MODE_CBC will be used.
*
* @param optional Integer $mode
* @return Crypt_TripleDES
* @access public
*/
function Crypt_TripleDES($mode = CRYPT_DES_MODE_CBC)
{
if ( !defined('CRYPT_DES_MODE') ) {
switch (true) {
case extension_loaded('mcrypt'):
// i'd check to see if des 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_DES_MODE', CRYPT_DES_MODE_MCRYPT);
break;
default:
define('CRYPT_DES_MODE', CRYPT_DES_MODE_INTERNAL);
}
}
if ( $mode == CRYPT_DES_MODE_3CBC ) {
$this->mode = CRYPT_DES_MODE_3CBC;
$this->des = array(
new Crypt_DES(CRYPT_DES_MODE_CBC),
new Crypt_DES(CRYPT_DES_MODE_CBC),
new Crypt_DES(CRYPT_DES_MODE_CBC)
);
// we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects
$this->des[0]->disablePadding();
$this->des[1]->disablePadding();
$this->des[2]->disablePadding();
return;
}
switch ( CRYPT_DES_MODE ) {
case CRYPT_DES_MODE_MCRYPT:
switch ($mode) {
case CRYPT_DES_MODE_ECB:
$this->mode = MCRYPT_MODE_ECB;
break;
case CRYPT_DES_MODE_CTR:
$this->mode = 'ctr';
break;
case CRYPT_DES_MODE_CBC:
default:
$this->mode = MCRYPT_MODE_CBC;
}
break;
default:
$this->des = array(
new Crypt_DES(CRYPT_DES_MODE_ECB),
new Crypt_DES(CRYPT_DES_MODE_ECB),
new Crypt_DES(CRYPT_DES_MODE_ECB)
);
// we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects
$this->des[0]->disablePadding();
$this->des[1]->disablePadding();
$this->des[2]->disablePadding();
switch ($mode) {
case CRYPT_DES_MODE_ECB:
case CRYPT_DES_MODE_CTR:
case CRYPT_DES_MODE_CBC:
$this->mode = $mode;
break;
default:
$this->mode = CRYPT_DES_MODE_CBC;
}
}
}
/**
* Sets the key.
*
* Keys can be of any length. Triple DES, itself, can use 128-bit (eg. strlen($key) == 16) or
* 192-bit (eg. strlen($key) == 24) keys. This function pads and truncates $key as appropriate.
*
* DES also requires that every eighth bit be a parity bit, however, we'll ignore that.
*
* If the key is not explicitly set, it'll be assumed to be all zero's.
*
* @access public
* @param String $key
*/
function setKey($key)
{
$length = strlen($key);
if ($length > 8) {
$key = str_pad($key, 24, chr(0));
// if $key is between 64 and 128-bits, use the first 64-bits as the last, per this:
// http://php.net/function.mcrypt-encrypt#47973
//$key = $length <= 16 ? substr_replace($key, substr($key, 0, 8), 16) : substr($key, 0, 24);
}
$this->key = $key;
switch (true) {
case CRYPT_DES_MODE == CRYPT_DES_MODE_INTERNAL:
case $this->mode == CRYPT_DES_MODE_3CBC:
$this->des[0]->setKey(substr($key, 0, 8));
$this->des[1]->setKey(substr($key, 8, 8));
$this->des[2]->setKey(substr($key, 16, 8));
}
$this->changed = true;
}
/**
* Sets the initialization vector. (optional)
*
* SetIV is not required when CRYPT_DES_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)
{
$this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($iv, 0, 8), 8, chr(0));
if ($this->mode == CRYPT_DES_MODE_3CBC) {
$this->des[0]->setIV($iv);
$this->des[1]->setIV($iv);
$this->des[2]->setIV($iv);
}
$this->changed = true;
}
/**
* Generate CTR XOR encryption key
*
* Encrypt the output of this and XOR it against the ciphertext / plaintext to get the
* plaintext / ciphertext in CTR mode.
*
* @see Crypt_DES::decrypt()
* @see Crypt_DES::encrypt()
* @access public
* @param Integer $length
* @param String $iv
*/
function _generate_xor($length, &$iv)
{
$xor = '';
$num_blocks = ($length + 7) >> 3;
for ($i = 0; $i < $num_blocks; $i++) {
$xor.= $iv;
for ($j = 4; $j <= 8; $j+=4) {
$temp = substr($iv, -$j, 4);
switch ($temp) {
case "\xFF\xFF\xFF\xFF":
$iv = substr_replace($iv, "\x00\x00\x00\x00", -$j, 4);
break;
case "\x7F\xFF\xFF\xFF":
$iv = substr_replace($iv, "\x80\x00\x00\x00", -$j, 4);
break 2;
default:
extract(unpack('Ncount', $temp));
$iv = substr_replace($iv, pack('N', $count + 1), -$j, 4);
break 2;
}
}
}
return $xor;
}
/**
* Encrypts a message.
*
* @access public
* @param String $plaintext
*/
function encrypt($plaintext)
{
if ($this->mode != CRYPT_DES_MODE_CTR && $this->mode != 'ctr') {
$plaintext = $this->_pad($plaintext);
}
// if the key is smaller then 8, do what we'd normally do
if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) {
$ciphertext = $this->des[2]->encrypt($this->des[1]->decrypt($this->des[0]->encrypt($plaintext)));
return $ciphertext;
}
if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) {
if ($this->changed) {
if (!isset($this->enmcrypt)) {
$this->enmcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, '');
}
mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
$this->changed = false;
}
$ciphertext = mcrypt_generic($this->enmcrypt, $plaintext);
if (!$this->continuousBuffer) {
mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
}
return $ciphertext;
}
if (strlen($this->key) <= 8) {
$this->des[0]->mode = $this->mode;
return $this->des[0]->encrypt($plaintext);
}
// 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."
$plaintext = str_pad($plaintext, ceil(strlen($plaintext) / 8) * 8, chr(0));
$des = $this->des;
$ciphertext = '';
switch ($this->mode) {
case CRYPT_DES_MODE_ECB:
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$block = substr($plaintext, $i, 8);
$block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
$block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT);
$block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT);
$ciphertext.= $block;
}
break;
case CRYPT_DES_MODE_CBC:
$xor = $this->encryptIV;
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$block = substr($plaintext, $i, 8) ^ $xor;
$block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT);
$block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT);
$block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT);
$xor = $block;
$ciphertext.= $block;
}
if ($this->continuousBuffer) {
$this->encryptIV = $xor;
}
break;
case CRYPT_DES_MODE_CTR:
$xor = $this->encryptIV;
for ($i = 0; $i < strlen($plaintext); $i+=8) {
$key = $this->_generate_xor(8, $xor);
$key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
$key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
$key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
$block = substr($plaintext, $i, 8);
$ciphertext.= $block ^ $key;
}
if ($this->continuousBuffer) {
$this->encryptIV = $xor;
}
}
return $ciphertext;
}
/**
* Decrypts a message.
*
* @access public
* @param String $ciphertext
*/
function decrypt($ciphertext)
{
if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) {
$plaintext = $this->des[0]->decrypt($this->des[1]->encrypt($this->des[2]->decrypt($ciphertext)));
return $this->_unpad($plaintext);
}
// 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($ciphertext) + 7) & 0xFFFFFFF8, chr(0));
if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) {
if ($this->changed) {
if (!isset($this->demcrypt)) {
$this->demcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, '');
}
mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
$this->changed = false;
}
$plaintext = mdecrypt_generic($this->demcrypt, $ciphertext);
if (!$this->continuousBuffer) {
mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
}
return $this->mode != 'ctr' ? $this->_unpad($plaintext) : $plaintext;
}
if (strlen($this->key) <= 8) {
$this->des[0]->mode = $this->mode;
return $this->_unpad($this->des[0]->decrypt($plaintext));
}
$des = $this->des;
$plaintext = '';
switch ($this->mode) {
case CRYPT_DES_MODE_ECB:
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$block = substr($ciphertext, $i, 8);
$block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT);
$block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT);
$block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT);
$plaintext.= $block;
}
break;
case CRYPT_DES_MODE_CBC:
$xor = $this->decryptIV;
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$orig = $block = substr($ciphertext, $i, 8);
$block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT);
$block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT);
$block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT);
$plaintext.= $block ^ $xor;
$xor = $orig;
}
if ($this->continuousBuffer) {
$this->decryptIV = $xor;
}
break;
case CRYPT_DES_MODE_CTR:
$xor = $this->decryptIV;
for ($i = 0; $i < strlen($ciphertext); $i+=8) {
$key = $this->_generate_xor(8, $xor);
$key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT);
$key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT);
$key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT);
$block = substr($ciphertext, $i, 8);
$plaintext.= $block ^ $key;
}
if ($this->continuousBuffer) {
$this->decryptIV = $xor;
}
}
return $this->mode != CRYPT_DES_MODE_CTR ? $this->_unpad($plaintext) : $plaintext;
}
/**
* Treat consecutive "packets" as if they are a continuous buffer.
*
* Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets
* will yield different outputs:
*
* <code>
* echo $des->encrypt(substr($plaintext, 0, 8));
* echo $des->encrypt(substr($plaintext, 8, 8));
* </code>
* <code>
* echo $des->encrypt($plaintext);
* </code>
*
* The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates
* another, as demonstrated with the following:
*
* <code>
* $des->encrypt(substr($plaintext, 0, 8));
* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
* </code>
* <code>
* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
* </code>
*
* With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different
* outputs. The reason is due to the fact that the initialization vector's change after every encryption /
* decryption round when the continuous buffer is enabled. When it's disabled, they remain constant.
*
* Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each
* encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that
* continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them),
* however, they are also less intuitive and more likely to cause you problems.
*
* @see Crypt_TripleDES::disableContinuousBuffer()
* @access public
*/
function enableContinuousBuffer()
{
$this->continuousBuffer = true;
if ($this->mode == CRYPT_DES_MODE_3CBC) {
$this->des[0]->enableContinuousBuffer();
$this->des[1]->enableContinuousBuffer();
$this->des[2]->enableContinuousBuffer();
}
}
/**
* Treat consecutive packets as if they are a discontinuous buffer.
*
* The default behavior.
*
* @see Crypt_TripleDES::enableContinuousBuffer()
* @access public
*/
function disableContinuousBuffer()
{
$this->continuousBuffer = false;
$this->encryptIV = $this->iv;
$this->decryptIV = $this->iv;
if ($this->mode == CRYPT_DES_MODE_3CBC) {
$this->des[0]->disableContinuousBuffer();
$this->des[1]->disableContinuousBuffer();
$this->des[2]->disableContinuousBuffer();
}
}
/**
* Pad "packets".
*
* DES works by encrypting eight bytes at a time. If you ever need to encrypt or decrypt something that's not
* a multiple of eight, it becomes necessary to pad the input so that it's length is a multiple of eight.
*
* Padding is enabled by default. Sometimes, however, it is undesirable to pad strings. Such is the case in SSH1,
* where "packets" are padded with random bytes before being encrypted. Unpad these packets and you risk stripping
* away characters that shouldn't be stripped away. (SSH knows how many bytes are added because the length is
* transmitted separately)
*
* @see Crypt_TripleDES::disablePadding()
* @access public
*/
function enablePadding()
{
$this->padding = true;
}
/**
* Do not pad packets.
*
* @see Crypt_TripleDES::enablePadding()
* @access public
*/
function disablePadding()
{
$this->padding = false;
}
/**
* Pads a string
*
* Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize (8).
* 8 - (strlen($text) & 7) bytes are added, each of which is equal to chr(8 - (strlen($text) & 7)
*
* If padding is disabled and $text is not a multiple of the blocksize, the string will be padded regardless
* and padding will, hence forth, be enabled.
*
* @see Crypt_TripleDES::_unpad()
* @access private
*/
function _pad($text)
{
$length = strlen($text);
if (!$this->padding) {
if (($length & 7) == 0) {
return $text;
} else {
user_error("The plaintext's length ($length) is not a multiple of the block size (8)", E_USER_NOTICE);
$this->padding = true;
}
}
$pad = 8 - ($length & 7);
return str_pad($text, $length + $pad, chr($pad));
}
/**
* Unpads a string
*
* If padding is enabled and the reported padding length is invalid the encryption key will be assumed to be wrong
* and false will be returned.
*
* @see Crypt_TripleDES::_pad()
* @access private
*/
function _unpad($text)
{
if (!$this->padding) {
return $text;
}
$length = ord($text[strlen($text) - 1]);
if (!$length || $length > 8) {
return false;
}
return substr($text, 0, -$length);
}
}
// vim: ts=4:sw=4:et:
// vim6: fdl=1: