461 lines
14 KiB
PHP
461 lines
14 KiB
PHP
<?php
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/**
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* Pure-PHP implementation of Triple DES.
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*
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* Uses mcrypt, if available, and an internal implementation, otherwise. Operates in the EDE3 mode (encrypt-decrypt-encrypt).
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*
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* PHP version 5
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*
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* Here's a short example of how to use this library:
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* <code>
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* <?php
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* include 'vendor/autoload.php';
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*
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* $des = new \phpseclib\Crypt\TripleDES();
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*
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* $des->setKey('abcdefghijklmnopqrstuvwx');
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*
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* $size = 10 * 1024;
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* $plaintext = '';
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* for ($i = 0; $i < $size; $i++) {
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* $plaintext.= 'a';
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* }
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*
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* echo $des->decrypt($des->encrypt($plaintext));
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* ?>
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* </code>
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*
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* @category Crypt
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* @package TripleDES
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* @author Jim Wigginton <terrafrost@php.net>
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* @copyright 2007 Jim Wigginton
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* @license http://www.opensource.org/licenses/mit-license.html MIT License
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* @link http://phpseclib.sourceforge.net
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*/
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namespace phpseclib\Crypt;
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/**
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* Pure-PHP implementation of Triple DES.
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*
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* @package TripleDES
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* @author Jim Wigginton <terrafrost@php.net>
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* @access public
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*/
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class TripleDES extends DES
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{
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/**
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* Encrypt / decrypt using inner chaining
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*
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* Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (self::MODE_CBC3).
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*/
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const MODE_3CBC = -2;
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/**
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* Encrypt / decrypt using outer chaining
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*
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* Outer chaining is used by SSH-2 and when the mode is set to \phpseclib\Crypt\Base::MODE_CBC.
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*/
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const MODE_CBC3 = Base::MODE_CBC;
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/**
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* Key Length (in bytes)
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*
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* @see \phpseclib\Crypt\TripleDES::setKeyLength()
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* @var int
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* @access private
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*/
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var $key_length = 24;
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/**
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* The default salt used by setPassword()
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*
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* @see \phpseclib\Crypt\Base::password_default_salt
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* @see \phpseclib\Crypt\Base::setPassword()
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* @var string
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* @access private
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*/
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var $password_default_salt = 'phpseclib';
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/**
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* The mcrypt specific name of the cipher
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*
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* @see \phpseclib\Crypt\DES::cipher_name_mcrypt
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* @see \phpseclib\Crypt\Base::cipher_name_mcrypt
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* @var string
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* @access private
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*/
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var $cipher_name_mcrypt = 'tripledes';
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/**
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* Optimizing value while CFB-encrypting
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*
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* @see \phpseclib\Crypt\Base::cfb_init_len
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* @var int
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* @access private
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*/
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var $cfb_init_len = 750;
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/**
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* max possible size of $key
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*
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* @see self::setKey()
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* @see \phpseclib\Crypt\DES::setKey()
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* @var string
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* @access private
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*/
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var $key_length_max = 24;
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/**
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* Internal flag whether using self::MODE_3CBC or not
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*
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* @var bool
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* @access private
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*/
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var $mode_3cbc;
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/**
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* The \phpseclib\Crypt\DES objects
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*
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* Used only if $mode_3cbc === true
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*
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* @var array
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* @access private
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*/
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var $des;
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/**
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* Default Constructor.
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*
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* Determines whether or not the mcrypt extension should be used.
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*
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* $mode could be:
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*
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* - \phpseclib\Crypt\Base::MODE_ECB
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*
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* - \phpseclib\Crypt\Base::MODE_CBC
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*
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* - \phpseclib\Crypt\Base::MODE_CTR
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*
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* - \phpseclib\Crypt\Base::MODE_CFB
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*
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* - \phpseclib\Crypt\Base::MODE_OFB
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*
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* - \phpseclib\Crypt\TripleDES::MODE_3CBC
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*
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* If not explicitly set, \phpseclib\Crypt\Base::MODE_CBC will be used.
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*
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* @see \phpseclib\Crypt\DES::__construct()
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* @see \phpseclib\Crypt\Base::__construct()
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* @param int $mode
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* @access public
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*/
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function __construct($mode = Base::MODE_CBC)
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{
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switch ($mode) {
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// In case of self::MODE_3CBC, we init as CRYPT_DES_MODE_CBC
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// and additional flag us internally as 3CBC
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case self::MODE_3CBC:
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parent::__construct(Base::MODE_CBC);
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$this->mode_3cbc = true;
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// This three $des'es will do the 3CBC work (if $key > 64bits)
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$this->des = array(
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new DES(Base::MODE_CBC),
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new DES(Base::MODE_CBC),
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new DES(Base::MODE_CBC),
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);
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// we're going to be doing the padding, ourselves, so disable it in the \phpseclib\Crypt\DES objects
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$this->des[0]->disablePadding();
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$this->des[1]->disablePadding();
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$this->des[2]->disablePadding();
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break;
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// If not 3CBC, we init as usual
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default:
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parent::__construct($mode);
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}
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}
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/**
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* Test for engine validity
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*
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* This is mainly just a wrapper to set things up for \phpseclib\Crypt\Base::isValidEngine()
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*
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* @see \phpseclib\Crypt\Base::__construct()
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* @param int $engine
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* @access public
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* @return bool
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*/
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function isValidEngine($engine)
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{
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if ($engine == self::ENGINE_OPENSSL) {
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$this->cipher_name_openssl_ecb = 'des-ede3';
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$mode = $this->_openssl_translate_mode();
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$this->cipher_name_openssl = $mode == 'ecb' ? 'des-ede3' : 'des-ede3-' . $mode;
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}
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return parent::isValidEngine($engine);
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}
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/**
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* Sets the initialization vector. (optional)
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*
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* SetIV is not required when \phpseclib\Crypt\Base::MODE_ECB is being used. If not explicitly set, it'll be assumed
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* to be all zero's.
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*
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* @see \phpseclib\Crypt\Base::setIV()
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* @access public
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* @param string $iv
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*/
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function setIV($iv)
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{
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parent::setIV($iv);
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if ($this->mode_3cbc) {
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$this->des[0]->setIV($iv);
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$this->des[1]->setIV($iv);
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$this->des[2]->setIV($iv);
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}
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}
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/**
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* Sets the key length.
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*
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* Valid key lengths are 64, 128 and 192
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*
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* @see \phpseclib\Crypt\Base:setKeyLength()
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* @access public
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* @param int $length
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*/
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function setKeyLength($length)
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{
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$length >>= 3;
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switch (true) {
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case $length <= 8:
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$this->key_length = 8;
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break;
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case $length <= 16:
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$this->key_length = 16;
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break;
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default:
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$this->key_length = 24;
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}
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parent::setKeyLength($length);
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}
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/**
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* Sets the key.
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*
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* Keys can be of any length. Triple DES, itself, can use 128-bit (eg. strlen($key) == 16) or
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* 192-bit (eg. strlen($key) == 24) keys. This function pads and truncates $key as appropriate.
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*
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* DES also requires that every eighth bit be a parity bit, however, we'll ignore that.
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*
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* If the key is not explicitly set, it'll be assumed to be all null bytes.
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*
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* @access public
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* @see \phpseclib\Crypt\DES::setKey()
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* @see \phpseclib\Crypt\Base::setKey()
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* @param string $key
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*/
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function setKey($key)
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{
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$length = $this->explicit_key_length ? $this->key_length : strlen($key);
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if ($length > 8) {
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$key = str_pad(substr($key, 0, 24), 24, chr(0));
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// if $key is between 64 and 128-bits, use the first 64-bits as the last, per this:
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// http://php.net/function.mcrypt-encrypt#47973
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$key = $length <= 16 ? substr_replace($key, substr($key, 0, 8), 16) : substr($key, 0, 24);
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} else {
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$key = str_pad($key, 8, chr(0));
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}
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parent::setKey($key);
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// And in case of self::MODE_3CBC:
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// if key <= 64bits we not need the 3 $des to work,
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// because we will then act as regular DES-CBC with just a <= 64bit key.
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// So only if the key > 64bits (> 8 bytes) we will call setKey() for the 3 $des.
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if ($this->mode_3cbc && $length > 8) {
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$this->des[0]->setKey(substr($key, 0, 8));
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$this->des[1]->setKey(substr($key, 8, 8));
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$this->des[2]->setKey(substr($key, 16, 8));
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}
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}
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/**
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* Encrypts a message.
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*
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* @see \phpseclib\Crypt\Base::encrypt()
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* @access public
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* @param string $plaintext
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* @return string $cipertext
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*/
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function encrypt($plaintext)
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{
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// parent::en/decrypt() is able to do all the work for all modes and keylengths,
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// except for: self::MODE_3CBC (inner chaining CBC) with a key > 64bits
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// if the key is smaller then 8, do what we'd normally do
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if ($this->mode_3cbc && strlen($this->key) > 8) {
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return $this->des[2]->encrypt(
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$this->des[1]->decrypt(
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$this->des[0]->encrypt(
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$this->_pad($plaintext)
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)
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)
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);
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}
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return parent::encrypt($plaintext);
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}
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/**
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* Decrypts a message.
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*
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* @see \phpseclib\Crypt\Base::decrypt()
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* @access public
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* @param string $ciphertext
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* @return string $plaintext
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*/
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function decrypt($ciphertext)
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{
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if ($this->mode_3cbc && strlen($this->key) > 8) {
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return $this->_unpad(
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$this->des[0]->decrypt(
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$this->des[1]->encrypt(
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$this->des[2]->decrypt(
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str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, "\0")
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)
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)
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)
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);
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}
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return parent::decrypt($ciphertext);
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}
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/**
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* Treat consecutive "packets" as if they are a continuous buffer.
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*
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* Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets
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* will yield different outputs:
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*
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* <code>
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* echo $des->encrypt(substr($plaintext, 0, 8));
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* echo $des->encrypt(substr($plaintext, 8, 8));
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* </code>
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* <code>
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* echo $des->encrypt($plaintext);
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* </code>
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*
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* The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates
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* another, as demonstrated with the following:
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*
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* <code>
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* $des->encrypt(substr($plaintext, 0, 8));
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* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
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* </code>
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* <code>
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* echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
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* </code>
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*
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* With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different
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* outputs. The reason is due to the fact that the initialization vector's change after every encryption /
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* decryption round when the continuous buffer is enabled. When it's disabled, they remain constant.
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*
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* Put another way, when the continuous buffer is enabled, the state of the \phpseclib\Crypt\DES() object changes after each
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* encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that
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* continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them),
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* however, they are also less intuitive and more likely to cause you problems.
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*
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* @see \phpseclib\Crypt\Base::enableContinuousBuffer()
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* @see self::disableContinuousBuffer()
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* @access public
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*/
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function enableContinuousBuffer()
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{
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parent::enableContinuousBuffer();
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if ($this->mode_3cbc) {
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$this->des[0]->enableContinuousBuffer();
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$this->des[1]->enableContinuousBuffer();
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$this->des[2]->enableContinuousBuffer();
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}
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}
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/**
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* Treat consecutive packets as if they are a discontinuous buffer.
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*
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* The default behavior.
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*
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* @see \phpseclib\Crypt\Base::disableContinuousBuffer()
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* @see self::enableContinuousBuffer()
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* @access public
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*/
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function disableContinuousBuffer()
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{
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parent::disableContinuousBuffer();
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if ($this->mode_3cbc) {
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$this->des[0]->disableContinuousBuffer();
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$this->des[1]->disableContinuousBuffer();
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$this->des[2]->disableContinuousBuffer();
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}
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}
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/**
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* Creates the key schedule
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*
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* @see \phpseclib\Crypt\DES::_setupKey()
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* @see \phpseclib\Crypt\Base::_setupKey()
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* @access private
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*/
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function _setupKey()
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{
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switch (true) {
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// if $key <= 64bits we configure our internal pure-php cipher engine
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// to act as regular [1]DES, not as 3DES. mcrypt.so::tripledes does the same.
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case strlen($this->key) <= 8:
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$this->des_rounds = 1;
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break;
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// otherwise, if $key > 64bits, we configure our engine to work as 3DES.
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default:
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$this->des_rounds = 3;
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// (only) if 3CBC is used we have, of course, to setup the $des[0-2] keys also separately.
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if ($this->mode_3cbc) {
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$this->des[0]->_setupKey();
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$this->des[1]->_setupKey();
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$this->des[2]->_setupKey();
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// because $des[0-2] will, now, do all the work we can return here
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// not need unnecessary stress parent::_setupKey() with our, now unused, $key.
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return;
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}
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}
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// setup our key
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parent::_setupKey();
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}
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/**
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* Sets the internal crypt engine
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*
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* @see \phpseclib\Crypt\Base::__construct()
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* @see \phpseclib\Crypt\Base::setPreferredEngine()
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* @param int $engine
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* @access public
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* @return int
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*/
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function setPreferredEngine($engine)
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{
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if ($this->mode_3cbc) {
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$this->des[0]->setPreferredEngine($engine);
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$this->des[1]->setPreferredEngine($engine);
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$this->des[2]->setPreferredEngine($engine);
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}
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return parent::setPreferredEngine($engine);
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}
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}
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