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<?php
/**
* Pure-PHP implementation of Triple DES.
*
* Uses mcrypt, if available, and an internal implementation, otherwise. Operates in the EDE3 mode (encrypt-decrypt-encrypt).
*
* PHP version 5
*
* Here's a short example of how to use this library:
* <code>
* <?php
* include 'phpseclib/autoload.php';
*
* $des = new \phpseclib\Crypt\TripleDES();
*
* $des->setKey('abcdefghijklmnopqrstuvwx');
*
* $size = 10 * 1024;
* $plaintext = '';
* for ($i = 0; $i < $size; $i++) {
* $plaintext.= 'a';
* }
*
* echo $des->decrypt($des->encrypt($plaintext));
* ?>
* </code>
*
* @category Crypt
* @package TripleDES
* @author Jim Wigginton <[email protected]>
* @copyright 2007 Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
*/
namespace phpseclib\Crypt;
/**
* Pure-PHP implementation of Triple DES.
*
* @package TripleDES
* @author Jim Wigginton <[email protected]>
* @access public
*/
class TripleDES extends DES
{
/**
* Encrypt / decrypt using inner chaining
*
* Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (self::MODE_CBC3).
*/
const MODE_3CBC = -2;
/**
* Encrypt / decrypt using outer chaining
*
* Outer chaining is used by SSH-2 and when the mode is set to \phpseclib\Crypt\Base::MODE_CBC.
*/
const MODE_CBC3 = Base::MODE_CBC;
/**
* Key Length (in bytes)
*
* @see \phpseclib\Crypt\TripleDES::setKeyLength()
* @var int
* @access private
*/
var $key_length = 24;
/**
* The default salt used by setPassword()
*
* @see \phpseclib\Crypt\Base::password_default_salt
* @see \phpseclib\Crypt\Base::setPassword()
* @var string
* @access private
*/
var $password_default_salt = 'phpseclib';
/**
* The mcrypt specific name of the cipher
*
* @see \phpseclib\Crypt\DES::cipher_name_mcrypt
* @see \phpseclib\Crypt\Base::cipher_name_mcrypt
* @var string
* @access private
*/
var $cipher_name_mcrypt = 'tripledes';
/**
* Optimizing value while CFB-encrypting
*
* @see \phpseclib\Crypt\Base::cfb_init_len
* @var int
* @access private
*/
var $cfb_init_len = 750;
/**
* max possible size of $key
*
* @see self::setKey()
* @see \phpseclib\Crypt\DES::setKey()
* @var string
* @access private
*/
var $key_length_max = 24;
/**
* Internal flag whether using self::MODE_3CBC or not
*
* @var bool
* @access private
*/
var $mode_3cbc;
/**
* The \phpseclib\Crypt\DES objects
*
* Used only if $mode_3cbc === true
*
* @var array
* @access private
*/
var $des;
/**
* Default Constructor.
*
* Determines whether or not the mcrypt extension should be used.
*
* $mode could be:
*
* - \phpseclib\Crypt\Base::MODE_ECB
*
* - \phpseclib\Crypt\Base::MODE_CBC
*
* - \phpseclib\Crypt\Base::MODE_CTR
*
* - \phpseclib\Crypt\Base::MODE_CFB
*
* - \phpseclib\Crypt\Base::MODE_OFB
*
* - \phpseclib\Crypt\TripleDES::MODE_3CBC
*
* If not explicitly set, \phpseclib\Crypt\Base::MODE_CBC will be used.
*
* @see \phpseclib\Crypt\DES::__construct()
* @see \phpseclib\Crypt\Base::__construct()
* @param int $mode
* @access public
*/
function __construct($mode = Base::MODE_CBC)
{
switch ($mode) {
// In case of self::MODE_3CBC, we init as CRYPT_DES_MODE_CBC
// and additional flag us internally as 3CBC
case self::MODE_3CBC:
parent::__construct(Base::MODE_CBC);
$this->mode_3cbc = true;
// This three $des'es will do the 3CBC work (if $key > 64bits)
$this->des = array(
new DES(Base::MODE_CBC),
new DES(Base::MODE_CBC),
new DES(Base::MODE_CBC),
);
// we're going to be doing the padding, ourselves, so disable it in the \phpseclib\Crypt\DES objects
$this->des[0]->disablePadding();
$this->des[1]->disablePadding();
$this->des[2]->disablePadding();
break;
// If not 3CBC, we init as usual
default:
parent::__construct($mode);
}
}
/**
* Test for engine validity
*
* This is mainly just a wrapper to set things up for \phpseclib\Crypt\Base::isValidEngine()
*
* @see \phpseclib\Crypt\Base::__construct()
* @param int $engine
* @access public
* @return bool
*/
function isValidEngine($engine)
{
if ($engine == self::ENGINE_OPENSSL) {
$this->cipher_name_openssl_ecb = 'des-ede3';
$mode = $this->_openssl_translate_mode();
$this->cipher_name_openssl = $mode == 'ecb' ? 'des-ede3' : 'des-ede3-' . $mode;
}
return parent::isValidEngine($engine);
}
/**
* Sets the initialization vector. (optional)
*
* SetIV is not required when \phpseclib\Crypt\Base::MODE_ECB is being used. If not explicitly set, it'll be assumed
* to be all zero's.
*
* @see \phpseclib\Crypt\Base::setIV()
* @access public
* @param string $iv
*/
function setIV($iv)
{
parent::setIV($iv);
if ($this->mode_3cbc) {
$this->des[0]->setIV($iv);
$this->des[1]->setIV($iv);
$this->des[2]->setIV($iv);
}
}
/**
* Sets the key length.
*
* Valid key lengths are 64, 128 and 192
*
* @see \phpseclib\Crypt\Base:setKeyLength()
* @access public
* @param int $length
*/
function setKeyLength($length)
{
$length >>= 3;
switch (true) {
case $length <= 8:
$this->key_length = 8;
break;
case $length <= 16:
$this->key_length = 16;
break;
default:
$this->key_length = 24;
}
parent::setKeyLength($length);
}
/**
* 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 null bytes.
*
* @access public
* @see \phpseclib\Crypt\DES::setKey()
* @see \phpseclib\Crypt\Base::setKey()
* @param string $key
*/
function setKey($key)
{
$length = $this->explicit_key_length ? $this->key_length : strlen($key);
if ($length > 8) {
$key = str_pad(substr($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);
} else {
$key = str_pad($key, 8, chr(0));
}
parent::setKey($key);
// And in case of self::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));
}
}
/**
* Encrypts a message.
*
* @see \phpseclib\Crypt\Base::encrypt()
* @access public
* @param string $plaintext
* @return string $cipertext
*/
function encrypt($plaintext)
{
// parent::en/decrypt() is able to do all the work for all modes and keylengths,
// except for: self::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(
$this->des[1]->decrypt(
$this->des[0]->encrypt(
$this->_pad($plaintext)
)
)
);
}
return parent::encrypt($plaintext);
}
/**
* Decrypts a message.
*
* @see \phpseclib\Crypt\Base::decrypt()
* @access public
* @param string $ciphertext
* @return string $plaintext
*/
function decrypt($ciphertext)
{
if ($this->mode_3cbc && strlen($this->key) > 8) {
return $this->_unpad(
$this->des[0]->decrypt(
$this->des[1]->encrypt(
$this->des[2]->decrypt(
str_pad($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:
*
* <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($plaintext, 8, 8)));
* </code>
*
* With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different
* outputs. The reason is due to the fact that the initialization vector's change after every encryption /
* decryption round when the continuous buffer is enabled. When it's disabled, they remain constant.
*
* Put another way, when the continuous buffer is enabled, the state of the \phpseclib\Crypt\DES() object changes after each
* encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that
* continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them),
* however, they are also less intuitive and more likely to cause you problems.
*
* @see \phpseclib\Crypt\Base::enableContinuousBuffer()
* @see self::disableContinuousBuffer()
* @access public
*/
function enableContinuousBuffer()
{
parent::enableContinuousBuffer();
if ($this->mode_3cbc) {
$this->des[0]->enableContinuousBuffer();
$this->des[1]->enableContinuousBuffer();
$this->des[2]->enableContinuousBuffer();
}
}
/**
* Treat consecutive packets as if they are a discontinuous buffer.
*
* The default behavior.
*
* @see \phpseclib\Crypt\Base::disableContinuousBuffer()
* @see self::enableContinuousBuffer()
* @access public
*/
function disableContinuousBuffer()
{
parent::disableContinuousBuffer();
if ($this->mode_3cbc) {
$this->des[0]->disableContinuousBuffer();
$this->des[1]->disableContinuousBuffer();
$this->des[2]->disableContinuousBuffer();
}
}
/**
* Creates the key schedule
*
* @see \phpseclib\Crypt\DES::_setupKey()
* @see \phpseclib\Crypt\Base::_setupKey()
* @access private
*/
function _setupKey()
{
switch (true) {
// 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:
$this->des_rounds = 1;
break;
// otherwise, if $key > 64bits, we configure our engine to work as 3DES.
default:
$this->des_rounds = 3;
// (only) if 3CBC is used we have, of course, to setup the $des[0-2] keys also separately.
if ($this->mode_3cbc) {
$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.
return;
}
}
// setup our key
parent::_setupKey();
}
/**
* Sets the internal crypt engine
*
* @see \phpseclib\Crypt\Base::__construct()
* @see \phpseclib\Crypt\Base::setPreferredEngine()
* @param int $engine
* @access public
* @return int
*/
function setPreferredEngine($engine)
{
if ($this->mode_3cbc) {
$this->des[0]->setPreferredEngine($engine);
$this->des[1]->setPreferredEngine($engine);
$this->des[2]->setPreferredEngine($engine);
}
return parent::setPreferredEngine($engine);
}
}
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