* Pure-PHP implementation of Triple DES.
* Uses mcrypt, if available, and an internal implementation, otherwise. Operates in the EDE3 mode (encrypt-decrypt-encrypt).
* Here's a short example of how to use this library:
* include 'Crypt/TripleDES.php';
* $des = new Crypt_TripleDES();
* $des->setKey('abcdefghijklmnopqrstuvwx');
* for ($i = 0; $i < $size; $i++) {
* echo $des->decrypt($des->encrypt($plaintext));
* 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
* @package Crypt_TripleDES
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVII Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
if (!class_exists('Crypt_DES')) {
require_once dirname(__FILE__).'/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', -2);
* 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.
* @package Crypt_TripleDES
* @author Jim Wigginton <terrafrost@php.net>
class Crypt_TripleDES extends Crypt_DES
* The default password key_size used by setPassword()
* @see Crypt_DES::password_key_size
* @see Crypt_Base::password_key_size
* @see Crypt_Base::setPassword()
public $password_key_size = 24;
* The default salt used by setPassword()
* @see Crypt_Base::password_default_salt
* @see Crypt_Base::setPassword()
public $password_default_salt = 'phpseclib';
* The namespace used by the cipher for its constants.
* @see Crypt_DES::const_namespace
* @see Crypt_Base::const_namespace
public $const_namespace = 'DES';
* The mcrypt specific name of the cipher
* @see Crypt_DES::cipher_name_mcrypt
* @see Crypt_Base::cipher_name_mcrypt
public $cipher_name_mcrypt = 'tripledes';
* Optimizing value while CFB-encrypting
* @see Crypt_Base::cfb_init_len
public $cfb_init_len = 750;
* max possible size of $key
* @see Crypt_TripleDES::setKey()
* @see Crypt_DES::setKey()
public $key_size_max = 24;
* Internal flag whether using CRYPT_DES_MODE_3CBC or not
* Used only if $mode_3cbc === true
* Determines whether or not the mcrypt extension should be used.
* If not explicitly set, CRYPT_DES_MODE_CBC will be used.
* @see Crypt_DES::Crypt_DES()
* @see Crypt_Base::Crypt_Base()
* @param optional Integer $mode
public function __construct($mode = CRYPT_DES_MODE_CBC)
// In case of CRYPT_DES_MODE_3CBC, we init as CRYPT_DES_MODE_CBC
// and additional flag us internally as 3CBC
case CRYPT_DES_MODE_3CBC:
parent::__construct(CRYPT_DES_MODE_CBC);
// This three $des'es will do the 3CBC work (if $key > 64bits)
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();
$this->des[2]->disablePadding();
// If not 3CBC, we init as usual
parent::__construct($mode);
* Sets the initialization vector. (optional)
* SetIV is not required when CRYPT_DES_MODE_ECB is being used. If not explicitly set, it'll be assumed
* @see Crypt_Base::setIV()
public function setIV($iv)
$this->des[0]->setIV($iv);
$this->des[1]->setIV($iv);
$this->des[2]->setIV($iv);
* 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 $key as appropriate.
* DES also requires that every eighth bit be a parity bit, however, we'll ignore that.
* If the key is not explicitly set, it'll be assumed to be all null bytes.
* @see Crypt_DES::setKey()
* @see Crypt_Base::setKey()
public function setKey($key)
$key = str_pad(substr($key, 0, 24), 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);
$key = str_pad($key, 8, chr(0));
// And in case of CRYPT_DES_MODE_3CBC:
// if key <= 64bits we not need the 3 $des to work,
// because we will then act as regular DES-CBC with just a <= 64bit key.
// So only if the key > 64bits (> 8 bytes) we will call setKey() for the 3 $des.
if ($this->mode_3cbc && $length > 8) {
$this->des[0]->setKey(substr($key, 0, 8));
$this->des[1]->setKey(substr($key, 8, 8));
$this->des[2]->setKey(substr($key, 16, 8));
* @see Crypt_Base::encrypt()
* @param String $plaintext
* @return String $cipertext
public function encrypt($plaintext)
// parent::en/decrypt() is able to do all the work for all modes and keylengths,
// except for: CRYPT_DES_MODE_3CBC (inner chaining CBC) with a key > 64bits
// if the key is smaller then 8, do what we'd normally do
if ($this->mode_3cbc && strlen($this->key) > 8) {
return $this->des[2]->encrypt(
return parent::encrypt($plaintext);
* @see Crypt_Base::decrypt()
* @param String $ciphertext
* @return String $plaintext
public function decrypt($ciphertext)
if ($this->mode_3cbc && strlen($this->key) > 8) {
str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, "\0")
return parent::decrypt($ciphertext);
* 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:
* echo $des->encrypt(substr($plaintext, 0, 8));
* echo $des->encrypt(substr($plaintext, 8, 8));
* echo $des->encrypt($plaintext);
* The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates
* another, as demonstrated with the following:
* $des->encrypt(substr($plaintext, 0, 8));
* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
* 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_Base::enableContinuousBuffer()
* @see Crypt_TripleDES::disableContinuousBuffer()
public function enableContinuousBuffer()
parent::enableContinuousBuffer();
$this->des[0]->enableContinuousBuffer();
$this->des[1]->enableContinuousBuffer();
$this->des[2]->enableContinuousBuffer();
* Treat consecutive packets as if they are a discontinuous buffer.
* @see Crypt_Base::disableContinuousBuffer()
* @see Crypt_TripleDES::enableContinuousBuffer()
public function disableContinuousBuffer()
parent::disableContinuousBuffer();
$this->des[0]->disableContinuousBuffer();
$this->des[1]->disableContinuousBuffer();
$this->des[2]->disableContinuousBuffer();
* Creates the key schedule
* @see Crypt_DES::_setupKey()
* @see Crypt_Base::_setupKey()
public function _setupKey()
// if $key <= 64bits we configure our internal pure-php cipher engine
// to act as regular [1]DES, not as 3DES. mcrypt.so::tripledes does the same.
case strlen($this->key) <= 8:
// otherwise, if $key > 64bits, we configure our engine to work as 3DES.
// (only) if 3CBC is used we have, of course, to setup the $des[0-2] keys also separately.
$this->des[0]->_setupKey();
$this->des[1]->_setupKey();
$this->des[2]->_setupKey();
// because $des[0-2] will, now, do all the work we can return here
// not need unnecessary stress parent::_setupKey() with our, now unused, $key.
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