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Файл: oc-includes/phpseclib/Crypt/Base.php
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<?php

/**
 * Base Class for all Crypt_* cipher classes
 *
 * PHP versions 4 and 5
 *
 * Internally for phpseclib developers:
 *  If you plan to add a new cipher class, please note following rules:
 *
 *  - The new Crypt_* cipher class should extend Crypt_Base
 *
 *  - Following methods are then required to be overridden/overloaded:
 *
 *    - _encryptBlock()
 *
 *    - _decryptBlock()
 *
 *    - _setupKey()
 *
 *  - All other methods are optional to be overridden/overloaded
 *
 *  - Look at the source code of the current ciphers how they extend Crypt_Base
 *    and take one of them as a start up for the new cipher class.
 *
 *  - Please read all the other comments/notes/hints here also for each class var/method
 *
 * 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_Base
 * @author    Jim Wigginton <terrafrost@php.net>
 * @author    Hans-Juergen Petrich <petrich@tronic-media.com>
 * @copyright 2007 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

/**#@+
 * @access public
 * @see Crypt_Base::encrypt()
 * @see Crypt_Base::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_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_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_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_MODE_CFB'3);
/**
 * Encrypt / decrypt using the Output Feedback mode.
 *
 * @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Output_feedback_.28OFB.29
 */
define('CRYPT_MODE_OFB'4);
/**
 * Encrypt / decrypt using streaming mode.
 */
define('CRYPT_MODE_STREAM'5);
/**#@-*/

/**#@+
 * @access private
 * @see Crypt_Base::Crypt_Base()
 * @internal These constants are for internal use only
 */
/**
 * Base value for the internal implementation $engine switch
 */
define('CRYPT_ENGINE_INTERNAL'1);
/**
 * Base value for the mcrypt implementation $engine switch
 */
define('CRYPT_ENGINE_MCRYPT'2);
/**
 * Base value for the OpenSSL implementation $engine switch
 */
define('CRYPT_ENGINE_OPENSSL'3);
/**#@-*/

/**
 * Base Class for all Crypt_* cipher classes
 *
 * @package Crypt_Base
 * @author  Jim Wigginton <terrafrost@php.net>
 * @author  Hans-Juergen Petrich <petrich@tronic-media.com>
 * @access  public
 */
class Crypt_Base
{
    
/**
     * The Encryption Mode
     *
     * @see Crypt_Base::Crypt_Base()
     * @var Integer
     * @access private
     */
    
var $mode;

    
/**
     * The Block Length of the block cipher
     *
     * @var Integer
     * @access private
     */
    
var $block_size 16;

    
/**
     * The Key
     *
     * @see Crypt_Base::setKey()
     * @var String
     * @access private
     */
    
var $key "";

    
/**
     * The Initialization Vector
     *
     * @see Crypt_Base::setIV()
     * @var String
     * @access private
     */
    
var $iv;

    
/**
     * A "sliding" Initialization Vector
     *
     * @see Crypt_Base::enableContinuousBuffer()
     * @see Crypt_Base::_clearBuffers()
     * @var String
     * @access private
     */
    
var $encryptIV;

    
/**
     * A "sliding" Initialization Vector
     *
     * @see Crypt_Base::enableContinuousBuffer()
     * @see Crypt_Base::_clearBuffers()
     * @var String
     * @access private
     */
    
var $decryptIV;

    
/**
     * Continuous Buffer status
     *
     * @see Crypt_Base::enableContinuousBuffer()
     * @var Boolean
     * @access private
     */
    
var $continuousBuffer false;

    
/**
     * Encryption buffer for CTR, OFB and CFB modes
     *
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::_clearBuffers()
     * @var Array
     * @access private
     */
    
var $enbuffer;

    
/**
     * Decryption buffer for CTR, OFB and CFB modes
     *
     * @see Crypt_Base::decrypt()
     * @see Crypt_Base::_clearBuffers()
     * @var Array
     * @access private
     */
    
var $debuffer;

    
/**
     * 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_Base::encrypt()
     * @var Resource
     * @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_Base::decrypt()
     * @var Resource
     * @access private
     */
    
var $demcrypt;

    
/**
     * Does the enmcrypt resource need to be (re)initialized?
     *
     * @see Crypt_Twofish::setKey()
     * @see Crypt_Twofish::setIV()
     * @var Boolean
     * @access private
     */
    
var $enchanged true;

    
/**
     * Does the demcrypt resource need to be (re)initialized?
     *
     * @see Crypt_Twofish::setKey()
     * @see Crypt_Twofish::setIV()
     * @var Boolean
     * @access private
     */
    
var $dechanged true;

    
/**
     * mcrypt resource for CFB mode
     *
     * mcrypt's CFB mode, in (and only in) buffered context,
     * is broken, so phpseclib implements the CFB mode by it self,
     * even when the mcrypt php extension is available.
     *
     * In order to do the CFB-mode work (fast) phpseclib
     * use a separate ECB-mode mcrypt resource.
     *
     * @link http://phpseclib.sourceforge.net/cfb-demo.phps
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::decrypt()
     * @see Crypt_Base::_setupMcrypt()
     * @var Resource
     * @access private
     */
    
var $ecb;

    
/**
     * Optimizing value while CFB-encrypting
     *
     * Only relevant if $continuousBuffer enabled
     * and $engine == CRYPT_ENGINE_MCRYPT
     *
     * It's faster to re-init $enmcrypt if
     * $buffer bytes > $cfb_init_len than
     * using the $ecb resource furthermore.
     *
     * This value depends of the chosen cipher
     * and the time it would be needed for it's
     * initialization [by mcrypt_generic_init()]
     * which, typically, depends on the complexity
     * on its internaly Key-expanding algorithm.
     *
     * @see Crypt_Base::encrypt()
     * @var Integer
     * @access private
     */
    
var $cfb_init_len 600;

    
/**
     * Does internal cipher state need to be (re)initialized?
     *
     * @see setKey()
     * @see setIV()
     * @see disableContinuousBuffer()
     * @var Boolean
     * @access private
     */
    
var $changed true;

    
/**
     * Padding status
     *
     * @see Crypt_Base::enablePadding()
     * @var Boolean
     * @access private
     */
    
var $padding true;

    
/**
     * Is the mode one that is paddable?
     *
     * @see Crypt_Base::Crypt_Base()
     * @var Boolean
     * @access private
     */
    
var $paddable false;

    
/**
     * Holds which crypt engine internaly should be use,
     * which will be determined automatically on __construct()
     *
     * Currently available $engines are:
     * - CRYPT_ENGINE_OPENSSL  (very fast, php-extension: openssl, extension_loaded('openssl') required)
     * - CRYPT_ENGINE_MCRYPT   (fast, php-extension: mcrypt, extension_loaded('mcrypt') required)
     * - CRYPT_ENGINE_INTERNAL (slower, pure php-engine, no php-extension required)
     *
     * @see Crypt_Base::_setEngine()
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::decrypt()
     * @var Integer
     * @access private
     */
    
var $engine;

    
/**
     * Holds the preferred crypt engine
     *
     * @see Crypt_Base::_setEngine()
     * @see Crypt_Base::setPreferredEngine()
     * @var Integer
     * @access private
     */
    
var $preferredEngine;

    
/**
     * The mcrypt specific name of the cipher
     *
     * Only used if $engine == CRYPT_ENGINE_MCRYPT
     *
     * @link http://www.php.net/mcrypt_module_open
     * @link http://www.php.net/mcrypt_list_algorithms
     * @see Crypt_Base::_setupMcrypt()
     * @var String
     * @access private
     */
    
var $cipher_name_mcrypt;

    
/**
     * The openssl specific name of the cipher
     *
     * Only used if $engine == CRYPT_ENGINE_OPENSSL
     *
     * @link http://www.php.net/openssl-get-cipher-methods
     * @var String
     * @access private
     */
    
var $cipher_name_openssl;

    
/**
     * The openssl specific name of the cipher in ECB mode
     *
     * If OpenSSL does not support the mode we're trying to use (CTR)
     * it can still be emulated with ECB mode.
     *
     * @link http://www.php.net/openssl-get-cipher-methods
     * @var String
     * @access private
     */
    
var $cipher_name_openssl_ecb;

    
/**
     * The default password key_size used by setPassword()
     *
     * @see Crypt_Base::setPassword()
     * @var Integer
     * @access private
     */
    
var $password_key_size 32;

    
/**
     * The default salt used by setPassword()
     *
     * @see Crypt_Base::setPassword()
     * @var String
     * @access private
     */
    
var $password_default_salt 'phpseclib/salt';

    
/**
     * The namespace used by the cipher for its constants.
     *
     * ie: AES.php is using CRYPT_AES_MODE_* for its constants
     *     so $const_namespace is AES
     *
     *     DES.php is using CRYPT_DES_MODE_* for its constants
     *     so $const_namespace is DES... and so on
     *
     * All CRYPT_<$const_namespace>_MODE_* are aliases of
     * the generic CRYPT_MODE_* constants, so both could be used
     * for each cipher.
     *
     * Example:
     * $aes = new Crypt_AES(CRYPT_AES_MODE_CFB); // $aes will operate in cfb mode
     * $aes = new Crypt_AES(CRYPT_MODE_CFB);     // identical
     *
     * @see Crypt_Base::Crypt_Base()
     * @var String
     * @access private
     */
    
var $const_namespace;

    
/**
     * The name of the performance-optimized callback function
     *
     * Used by encrypt() / decrypt()
     * only if $engine == CRYPT_ENGINE_INTERNAL
     *
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::decrypt()
     * @see Crypt_Base::_setupInlineCrypt()
     * @see Crypt_Base::$use_inline_crypt
     * @var Callback
     * @access private
     */
    
var $inline_crypt;

    
/**
     * Holds whether performance-optimized $inline_crypt() can/should be used.
     *
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::decrypt()
     * @see Crypt_Base::inline_crypt
     * @var mixed
     * @access private
     */
    
var $use_inline_crypt;

    
/**
     * If OpenSSL can be used in ECB but not in CTR we can emulate CTR
     *
     * @see Crypt_Base::_openssl_ctr_process()
     * @var Boolean
     * @access private
     */
    
var $openssl_emulate_ctr false;

    
/**
     * Determines what options are passed to openssl_encrypt/decrypt
     *
     * @see Crypt_Base::isValidEngine()
     * @var mixed
     * @access private
     */
    
var $openssl_options;

    
/**
     * Default Constructor.
     *
     * Determines whether or not the mcrypt extension should be used.
     *
     * $mode could be:
     *
     * - CRYPT_MODE_ECB
     *
     * - CRYPT_MODE_CBC
     *
     * - CRYPT_MODE_CTR
     *
     * - CRYPT_MODE_CFB
     *
     * - CRYPT_MODE_OFB
     *
     * (or the alias constants of the chosen cipher, for example for AES: CRYPT_AES_MODE_ECB or CRYPT_AES_MODE_CBC ...)
     *
     * If not explicitly set, CRYPT_MODE_CBC will be used.
     *
     * @param optional Integer $mode
     * @access public
     */
    
function Crypt_Base($mode CRYPT_MODE_CBC)
    {
        
// $mode dependent settings
        
switch ($mode) {
            case 
CRYPT_MODE_ECB:
                
$this->paddable true;
                
$this->mode CRYPT_MODE_ECB;
                break;
            case 
CRYPT_MODE_CTR:
            case 
CRYPT_MODE_CFB:
            case 
CRYPT_MODE_OFB:
            case 
CRYPT_MODE_STREAM:
                
$this->mode $mode;
                break;
            case 
CRYPT_MODE_CBC:
            default:
                
$this->paddable true;
                
$this->mode CRYPT_MODE_CBC;
        }

        
$this->_setEngine();

        
// Determining whether inline crypting can be used by the cipher
        
if ($this->use_inline_crypt !== false && function_exists('create_function')) {
            
$this->use_inline_crypt true;
        }
    }

    
/**
     * Sets the initialization vector. (optional)
     *
     * SetIV is not required when CRYPT_MODE_ECB (or ie for AES: CRYPT_AES_MODE_ECB) is being used.  If not explicitly set, it'll be assumed
     * to be all zero's.
     *
     * @access public
     * @param String $iv
     * @internal Can be overwritten by a sub class, but does not have to be
     */
    
function setIV($iv)
    {
        if (
$this->mode == CRYPT_MODE_ECB) {
            return;
        }

        
$this->iv $iv;
        
$this->changed true;
    }

    
/**
     * Sets the key.
     *
     * The min/max length(s) of the key depends on the cipher which is used.
     * If the key not fits the length(s) of the cipher it will paded with null bytes
     * up to the closest valid key length.  If the key is more than max length,
     * we trim the excess bits.
     *
     * If the key is not explicitly set, it'll be assumed to be all null bytes.
     *
     * @access public
     * @param String $key
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function setKey($key)
    {
        
$this->key $key;
        
$this->changed true;
        
$this->_setEngine();
    }

    
/**
     * Sets the password.
     *
     * Depending on what $method is set to, setPassword()'s (optional) parameters are as follows:
     *     {@link http://en.wikipedia.org/wiki/PBKDF2 pbkdf2} or pbkdf1:
     *         $hash, $salt, $count, $dkLen
     *
     *         Where $hash (default = sha1) currently supports the following hashes: see: Crypt/Hash.php
     *
     * @see Crypt/Hash.php
     * @param String $password
     * @param optional String $method
     * @return Boolean
     * @access public
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function setPassword($password$method 'pbkdf2')
    {
        
$key '';

        switch (
$method) {
            default: 
// 'pbkdf2' or 'pbkdf1'
                
$func_args func_get_args();

                
// Hash function
                
$hash = isset($func_args[2]) ? $func_args[2] : 'sha1';

                
// WPA and WPA2 use the SSID as the salt
                
$salt = isset($func_args[3]) ? $func_args[3] : $this->password_default_salt;

                
// RFC2898#section-4.2 uses 1,000 iterations by default
                // WPA and WPA2 use 4,096.
                
$count = isset($func_args[4]) ? $func_args[4] : 1000;

                
// Keylength
                
if (isset($func_args[5])) {
                    
$dkLen $func_args[5];
                } else {
                    
$dkLen $method == 'pbkdf1' $this->password_key_size $this->password_key_size;
                }

                switch (
true) {
                    case 
$method == 'pbkdf1':
                        if (!
class_exists('Crypt_Hash')) {
                            include_once 
'Crypt/Hash.php';
                        }
                        
$hashObj = new Crypt_Hash();
                        
$hashObj->setHash($hash);
                        if (
$dkLen $hashObj->getLength()) {
                            
user_error('Derived key too long');
                            return 
false;
                        }
                        
$t $password $salt;
                        for (
$i 0$i $count; ++$i) {
                            
$t $hashObj->hash($t);
                        }
                        
$key substr($t0$dkLen);

                        
$this->setKey(substr($key0$dkLen >> 1));
                        
$this->setIV(substr($key$dkLen >> 1));

                        return 
true;
                    
// Determining if php[>=5.5.0]'s hash_pbkdf2() function avail- and useable
                    
case !function_exists('hash_pbkdf2'):
                    case !
function_exists('hash_algos'):
                    case !
in_array($hashhash_algos()):
                        if (!
class_exists('Crypt_Hash')) {
                            include_once 
'Crypt/Hash.php';
                        }
                        
$i 1;
                        while (
strlen($key) < $dkLen) {
                            
$hmac = new Crypt_Hash();
                            
$hmac->setHash($hash);
                            
$hmac->setKey($password);
                            
$f $u $hmac->hash($salt pack('N'$i++));
                            for (
$j 2$j <= $count; ++$j) {
                                
$u $hmac->hash($u);
                                
$f^= $u;
                            }
                            
$key.= $f;
                        }
                        
$key substr($key0$dkLen);
                        break;
                    default:
                        
$key hash_pbkdf2($hash$password$salt$count$dkLentrue);
                }
        }

        
$this->setKey($key);

        return 
true;
    }

    
/**
     * Encrypts a message.
     *
     * $plaintext will be padded with additional bytes such that it's length is a multiple of the block size. Other cipher
     * implementations may or may not pad in the same manner.  Other common approaches to padding and the reasons why it's
     * necessary are discussed in the following
     * URL:
     *
     * {@link http://www.di-mgt.com.au/cryptopad.html http://www.di-mgt.com.au/cryptopad.html}
     *
     * An alternative to padding is to, separately, send the length of the file.  This is what SSH, in fact, does.
     * strlen($plaintext) will still need to be a multiple of the block size, however, arbitrary values can be added to make it that
     * length.
     *
     * @see Crypt_Base::decrypt()
     * @access public
     * @param String $plaintext
     * @return String $ciphertext
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function encrypt($plaintext)
    {
        if (
$this->paddable) {
            
$plaintext $this->_pad($plaintext);
        }

        if (
$this->engine === CRYPT_ENGINE_OPENSSL) {
            if (
$this->changed) {
                
$this->_clearBuffers();
                
$this->changed false;
            }
            switch (
$this->mode) {
                case 
CRYPT_MODE_STREAM:
                    return 
openssl_encrypt($plaintext$this->cipher_name_openssl$this->key$this->openssl_options);
                case 
CRYPT_MODE_ECB:
                    
$result openssl_encrypt($plaintext$this->cipher_name_openssl$this->key$this->openssl_options);
                    return !
defined('OPENSSL_RAW_DATA') ? substr($result0, -$this->block_size) : $result;
                case 
CRYPT_MODE_CBC:
                    
$result openssl_encrypt($plaintext$this->cipher_name_openssl$this->key$this->openssl_options$this->encryptIV);
                    if (
$this->continuousBuffer) {
                        
$this->encryptIV substr($result, -$this->block_size);
                    }
                    return !
defined('OPENSSL_RAW_DATA') ? substr($result0, -$this->block_size) : $result;
                case 
CRYPT_MODE_CTR:
                    return 
$this->_openssl_ctr_process($plaintext$this->encryptIV$this->enbuffer);
                case 
CRYPT_MODE_CFB:
                    
// cfb loosely routines inspired by openssl's:
                    // {@link http://cvs.openssl.org/fileview?f=openssl/crypto/modes/cfb128.c&v=1.3.2.2.2.1}
                    
$ciphertext '';
                    if (
$this->continuousBuffer) {
                        
$iv = &$this->encryptIV;
                        
$pos = &$this->enbuffer['pos'];
                    } else {
                        
$iv $this->encryptIV;
                        
$pos 0;
                    }
                    
$len strlen($plaintext);
                    
$i 0;
                    if (
$pos) {
                        
$orig_pos $pos;
                        
$max $this->block_size $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
                        
$ciphertext substr($iv$orig_pos) ^ $plaintext;
                        
$iv substr_replace($iv$ciphertext$orig_pos$i);
                        
$plaintext substr($plaintext$i);
                    }

                    
$overflow $len $this->block_size;

                    if (
$overflow) {
                        
$ciphertext.= openssl_encrypt(substr($plaintext0, -$overflow) . str_repeat(""$this->block_size), $this->cipher_name_openssl$this->key$this->openssl_options$iv);
                        
$iv $this->_string_pop($ciphertext$this->block_size);

                        
$size $len $overflow;
                        
$block $iv substr($plaintext, -$overflow);
                        
$iv substr_replace($iv$block0$overflow);
                        
$ciphertext.= $block;
                        
$pos $overflow;
                    } elseif (
$len) {
                        
$ciphertext openssl_encrypt($plaintext$this->cipher_name_openssl$this->key$this->openssl_options$iv);
                        
$iv substr($ciphertext, -$this->block_size);
                    }

                    return 
$ciphertext;
                case 
CRYPT_MODE_OFB:
                    return 
$this->_openssl_ofb_process($plaintext$this->encryptIV$this->enbuffer);
            }
        }

        if (
$this->engine === CRYPT_ENGINE_MCRYPT) {
            if (
$this->changed) {
                
$this->_setupMcrypt();
                
$this->changed false;
            }
            if (
$this->enchanged) {
                
mcrypt_generic_init($this->enmcrypt$this->key$this->encryptIV);
                
$this->enchanged false;
            }

            
// re: {@link 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 == CRYPT_MODE_CFB && $this->continuousBuffer) {
                
$block_size $this->block_size;
                
$iv = &$this->encryptIV;
                
$pos = &$this->enbuffer['pos'];
                
$len strlen($plaintext);
                
$ciphertext '';
                
$i 0;
                if (
$pos) {
                    
$orig_pos $pos;
                    
$max $block_size $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 >= $block_size) {
                    if (
$this->enbuffer['enmcrypt_init'] === false || $len $this->cfb_init_len) {
                        if (
$this->enbuffer['enmcrypt_init'] === true) {
                            
mcrypt_generic_init($this->enmcrypt$this->key$iv);
                            
$this->enbuffer['enmcrypt_init'] = false;
                        }
                        
$ciphertext.= mcrypt_generic($this->enmcryptsubstr($plaintext$i$len $len $block_size));
                        
$iv substr($ciphertext, -$block_size);
                        
$len%= $block_size;
                    } else {
                        while (
$len >= $block_size) {
                            
$iv mcrypt_generic($this->ecb$iv) ^ substr($plaintext$i$block_size);
                            
$ciphertext.= $iv;
                            
$len-= $block_size;
                            
$i+= $block_size;
                        }
                    }
                }

                if (
$len) {
                    
$iv mcrypt_generic($this->ecb$iv);
                    
$block $iv substr($plaintext, -$len);
                    
$iv substr_replace($iv$block0$len);
                    
$ciphertext.= $block;
                    
$pos $len;
                }

                return 
$ciphertext;
            }

            
$ciphertext mcrypt_generic($this->enmcrypt$plaintext);

            if (!
$this->continuousBuffer) {
                
mcrypt_generic_init($this->enmcrypt$this->key$this->encryptIV);
            }

            return 
$ciphertext;
        }

        if (
$this->changed) {
            
$this->_setup();
            
$this->changed false;
        }
        if (
$this->use_inline_crypt) {
            
$inline $this->inline_crypt;
            return 
$inline('encrypt'$this$plaintext);
        }

        
$buffer = &$this->enbuffer;
        
$block_size $this->block_size;
        
$ciphertext '';
        switch (
$this->mode) {
            case 
CRYPT_MODE_ECB:
                for (
$i 0$i strlen($plaintext); $i+=$block_size) {
                    
$ciphertext.= $this->_encryptBlock(substr($plaintext$i$block_size));
                }
                break;
            case 
CRYPT_MODE_CBC:
                
$xor $this->encryptIV;
                for (
$i 0$i strlen($plaintext); $i+=$block_size) {
                    
$block substr($plaintext$i$block_size);
                    
$block $this->_encryptBlock($block $xor);
                    
$xor $block;
                    
$ciphertext.= $block;
                }
                if (
$this->continuousBuffer) {
                    
$this->encryptIV $xor;
                }
                break;
            case 
CRYPT_MODE_CTR:
                
$xor $this->encryptIV;
                if (
strlen($buffer['ciphertext'])) {
                    for (
$i 0$i strlen($plaintext); $i+=$block_size) {
                        
$block substr($plaintext$i$block_size);
                        if (
strlen($block) > strlen($buffer['ciphertext'])) {
                            
$buffer['ciphertext'].= $this->_encryptBlock($xor);
                        }
                        
$this->_increment_str($xor);
                        
$key $this->_string_shift($buffer['ciphertext'], $block_size);
                        
$ciphertext.= $block $key;
                    }
                } else {
                    for (
$i 0$i strlen($plaintext); $i+=$block_size) {
                        
$block substr($plaintext$i$block_size);
                        
$key $this->_encryptBlock($xor);
                        
$this->_increment_str($xor);
                        
$ciphertext.= $block $key;
                    }
                }
                if (
$this->continuousBuffer) {
                    
$this->encryptIV $xor;
                    if (
$start strlen($plaintext) % $block_size) {
                        
$buffer['ciphertext'] = substr($key$start) . $buffer['ciphertext'];
                    }
                }
                break;
            case 
CRYPT_MODE_CFB:
                
// cfb loosely routines inspired by openssl's:
                // {@link http://cvs.openssl.org/fileview?f=openssl/crypto/modes/cfb128.c&v=1.3.2.2.2.1}
                
if ($this->continuousBuffer) {
                    
$iv = &$this->encryptIV;
                    
$pos = &$buffer['pos'];
                } else {
                    
$iv $this->encryptIV;
                    
$pos 0;
                }
                
$len strlen($plaintext);
                
$i 0;
                if (
$pos) {
                    
$orig_pos $pos;
                    
$max $block_size $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
                    
$ciphertext substr($iv$orig_pos) ^ $plaintext;
                    
$iv substr_replace($iv$ciphertext$orig_pos$i);
                }
                while (
$len >= $block_size) {
                    
$iv $this->_encryptBlock($iv) ^ substr($plaintext$i$block_size);
                    
$ciphertext.= $iv;
                    
$len-= $block_size;
                    
$i+= $block_size;
                }
                if (
$len) {
                    
$iv $this->_encryptBlock($iv);
                    
$block $iv substr($plaintext$i);
                    
$iv substr_replace($iv$block0$len);
                    
$ciphertext.= $block;
                    
$pos $len;
                }
                break;
            case 
CRYPT_MODE_OFB:
                
$xor $this->encryptIV;
                if (
strlen($buffer['xor'])) {
                    for (
$i 0$i strlen($plaintext); $i+=$block_size) {
                        
$block substr($plaintext$i$block_size);
                        if (
strlen($block) > strlen($buffer['xor'])) {
                            
$xor $this->_encryptBlock($xor);
                            
$buffer['xor'].= $xor;
                        }
                        
$key $this->_string_shift($buffer['xor'], $block_size);
                        
$ciphertext.= $block $key;
                    }
                } else {
                    for (
$i 0$i strlen($plaintext); $i+=$block_size) {
                        
$xor $this->_encryptBlock($xor);
                        
$ciphertext.= substr($plaintext$i$block_size) ^ $xor;
                    }
                    
$key $xor;
                }
                if (
$this->continuousBuffer) {
                    
$this->encryptIV $xor;
                    if (
$start strlen($plaintext) % $block_size) {
                         
$buffer['xor'] = substr($key$start) . $buffer['xor'];
                    }
                }
                break;
            case 
CRYPT_MODE_STREAM:
                
$ciphertext $this->_encryptBlock($plaintext);
                break;
        }

        return 
$ciphertext;
    }

    
/**
     * Decrypts a message.
     *
     * If strlen($ciphertext) is not a multiple of the block size, null bytes will be added to the end of the string until
     * it is.
     *
     * @see Crypt_Base::encrypt()
     * @access public
     * @param String $ciphertext
     * @return String $plaintext
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function decrypt($ciphertext)
    {
        if (
$this->paddable) {
            
// we pad with chr(0) since that's what mcrypt_generic does.  to quote from {@link http://www.php.net/function.mcrypt-generic}:
            // "The data is padded with "" to make sure the length of the data is n * blocksize."
            
$ciphertext str_pad($ciphertextstrlen($ciphertext) + ($this->block_size strlen($ciphertext) % $this->block_size) % $this->block_sizechr(0));
        }

        if (
$this->engine === CRYPT_ENGINE_OPENSSL) {
            if (
$this->changed) {
                
$this->_clearBuffers();
                
$this->changed false;
            }
            switch (
$this->mode) {
                case 
CRYPT_MODE_STREAM:
                    
$plaintext openssl_decrypt($ciphertext$this->cipher_name_openssl$this->key$this->openssl_options);
                    break;
                case 
CRYPT_MODE_ECB:
                    if (!
defined('OPENSSL_RAW_DATA')) {
                        
$ciphetext.= openssl_encrypt(''$this->cipher_name_openssl_ecb$this->keytrue);
                    }
                    
$plaintext openssl_decrypt($ciphertext$this->cipher_name_openssl$this->key$this->openssl_options);
                    break;
                case 
CRYPT_MODE_CBC:
                    if (!
defined('OPENSSL_RAW_DATA')) {
                        
$padding str_repeat(chr($this->block_size), $this->block_size) ^ substr($ciphertext, -$this->block_size);
                        
$ciphertext.= substr(openssl_encrypt($padding$this->cipher_name_openssl_ecb$this->keytrue), 0$this->block_size);
                    }
                    
$plaintext openssl_decrypt($ciphertext$this->cipher_name_openssl$this->key$this->openssl_options$this->decryptIV);
                    if (
$this->continuousBuffer) {
                        
$this->decryptIV substr($ciphertext, -$this->block_size);
                    }
                    break;
                case 
CRYPT_MODE_CTR:
                    
$plaintext $this->_openssl_ctr_process($ciphertext$this->decryptIV$this->debuffer);
                    break;
                case 
CRYPT_MODE_CFB:
                    
// cfb loosely routines inspired by openssl's:
                    // {@link http://cvs.openssl.org/fileview?f=openssl/crypto/modes/cfb128.c&v=1.3.2.2.2.1}
                    
$plaintext '';
                    if (
$this->continuousBuffer) {
                        
$iv = &$this->decryptIV;
                        
$pos = &$this->buffer['pos'];
                    } else {
                        
$iv $this->decryptIV;
                        
$pos 0;
                    }
                    
$len strlen($ciphertext);
                    
$i 0;
                    if (
$pos) {
                        
$orig_pos $pos;
                        
$max $this->block_size $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%= $this->blocksize
                        
$plaintext substr($iv$orig_pos) ^ $ciphertext;
                        
$iv substr_replace($ivsubstr($ciphertext0$i), $orig_pos$i);
                        
$ciphertext substr($ciphertext$i);
                    }
                    
$overflow $len $this->block_size;
                    if (
$overflow) {
                        
$plaintext.= openssl_decrypt(substr($ciphertext0, -$overflow), $this->cipher_name_openssl$this->key$this->openssl_options$iv);
                        if (
$len $overflow) {
                            
$iv substr($ciphertext, -$overflow $this->block_size, -$overflow);
                        }
                        
$iv openssl_encrypt(str_repeat(""$this->block_size), $this->cipher_name_openssl$this->key$this->openssl_options$iv);
                        
$plaintext.= $iv substr($ciphertext, -$overflow);
                        
$iv substr_replace($ivsubstr($ciphertext, -$overflow), 0$overflow);
                        
$pos $overflow;
                    } elseif (
$len) {
                        
$plaintext.= openssl_decrypt($ciphertext$this->cipher_name_openssl$this->key$this->openssl_options$iv);
                        
$iv substr($ciphertext, -$this->block_size);
                    }
                    break;
                case 
CRYPT_MODE_OFB:
                    
$plaintext $this->_openssl_ofb_process($ciphertext$this->decryptIV$this->debuffer);
            }

            return 
$this->paddable $this->_unpad($plaintext) : $plaintext;
        }

        if (
$this->engine === CRYPT_ENGINE_MCRYPT) {
            
$block_size $this->block_size;
            if (
$this->changed) {
                
$this->_setupMcrypt();
                
$this->changed false;
            }
            if (
$this->dechanged) {
                
mcrypt_generic_init($this->demcrypt$this->key$this->decryptIV);
                
$this->dechanged false;
            }

            if (
$this->mode == CRYPT_MODE_CFB && $this->continuousBuffer) {
                
$iv = &$this->decryptIV;
                
$pos = &$this->debuffer['pos'];
                
$len strlen($ciphertext);
                
$plaintext '';
                
$i 0;
                if (
$pos) {
                    
$orig_pos $pos;
                    
$max $block_size $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;
                    
$iv substr_replace($ivsubstr($ciphertext0$i), $orig_pos$i);
                }
                if (
$len >= $block_size) {
                    
$cb substr($ciphertext$i$len $len $block_size);
                    
$plaintext.= mcrypt_generic($this->ecb$iv $cb) ^ $cb;
                    
$iv substr($cb, -$block_size);
                    
$len%= $block_size;
                }
                if (
$len) {
                    
$iv mcrypt_generic($this->ecb$iv);
                    
$plaintext.= $iv substr($ciphertext, -$len);
                    
$iv substr_replace($ivsubstr($ciphertext, -$len), 0$len);
                    
$pos $len;
                }

                return 
$plaintext;
            }

            
$plaintext mdecrypt_generic($this->demcrypt$ciphertext);

            if (!
$this->continuousBuffer) {
                
mcrypt_generic_init($this->demcrypt$this->key$this->decryptIV);
            }

            return 
$this->paddable $this->_unpad($plaintext) : $plaintext;
        }

        if (
$this->changed) {
            
$this->_setup();
            
$this->changed false;
        }
        if (
$this->use_inline_crypt) {
            
$inline $this->inline_crypt;
            return 
$inline('decrypt'$this$ciphertext);
        }

        
$block_size $this->block_size;

        
$buffer = &$this->debuffer;
        
$plaintext '';
        switch (
$this->mode) {
            case 
CRYPT_MODE_ECB:
                for (
$i 0$i strlen($ciphertext); $i+=$block_size) {
                    
$plaintext.= $this->_decryptBlock(substr($ciphertext$i$block_size));
                }
                break;
            case 
CRYPT_MODE_CBC:
                
$xor $this->decryptIV;
                for (
$i 0$i strlen($ciphertext); $i+=$block_size) {
                    
$block substr($ciphertext$i$block_size);
                    
$plaintext.= $this->_decryptBlock($block) ^ $xor;
                    
$xor $block;
                }
                if (
$this->continuousBuffer) {
                    
$this->decryptIV $xor;
                }
                break;
            case 
CRYPT_MODE_CTR:
                
$xor $this->decryptIV;
                if (
strlen($buffer['ciphertext'])) {
                    for (
$i 0$i strlen($ciphertext); $i+=$block_size) {
                        
$block substr($ciphertext$i$block_size);
                        if (
strlen($block) > strlen($buffer['ciphertext'])) {
                            
$buffer['ciphertext'].= $this->_encryptBlock($xor);
                            
$this->_increment_str($xor);
                        }
                        
$key $this->_string_shift($buffer['ciphertext'], $block_size);
                        
$plaintext.= $block $key;
                    }
                } else {
                    for (
$i 0$i strlen($ciphertext); $i+=$block_size) {
                        
$block substr($ciphertext$i$block_size);
                        
$key $this->_encryptBlock($xor);
                        
$this->_increment_str($xor);
                        
$plaintext.= $block $key;
                    }
                }
                if (
$this->continuousBuffer) {
                    
$this->decryptIV $xor;
                    if (
$start strlen($ciphertext) % $block_size) {
                        
$buffer['ciphertext'] = substr($key$start) . $buffer['ciphertext'];
                    }
                }
                break;
            case 
CRYPT_MODE_CFB:
                if (
$this->continuousBuffer) {
                    
$iv = &$this->decryptIV;
                    
$pos = &$buffer['pos'];
                } else {
                    
$iv $this->decryptIV;
                    
$pos 0;
                }
                
$len strlen($ciphertext);
                
$i 0;
                if (
$pos) {
                    
$orig_pos $pos;
                    
$max $block_size $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;
                    
$iv substr_replace($ivsubstr($ciphertext0$i), $orig_pos$i);
                }
                while (
$len >= $block_size) {
                    
$iv $this->_encryptBlock($iv);
                    
$cb substr($ciphertext$i$block_size);
                    
$plaintext.= $iv $cb;
                    
$iv $cb;
                    
$len-= $block_size;
                    
$i+= $block_size;
                }
                if (
$len) {
                    
$iv $this->_encryptBlock($iv);
                    
$plaintext.= $iv substr($ciphertext$i);
                    
$iv substr_replace($ivsubstr($ciphertext$i), 0$len);
                    
$pos $len;
                }
                break;
            case 
CRYPT_MODE_OFB:
                
$xor $this->decryptIV;
                if (
strlen($buffer['xor'])) {
                    for (
$i 0$i strlen($ciphertext); $i+=$block_size) {
                        
$block substr($ciphertext$i$block_size);
                        if (
strlen($block) > strlen($buffer['xor'])) {
                            
$xor $this->_encryptBlock($xor);
                            
$buffer['xor'].= $xor;
                        }
                        
$key $this->_string_shift($buffer['xor'], $block_size);
                        
$plaintext.= $block $key;
                    }
                } else {
                    for (
$i 0$i strlen($ciphertext); $i+=$block_size) {
                        
$xor $this->_encryptBlock($xor);
                        
$plaintext.= substr($ciphertext$i$block_size) ^ $xor;
                    }
                    
$key $xor;
                }
                if (
$this->continuousBuffer) {
                    
$this->decryptIV $xor;
                    if (
$start strlen($ciphertext) % $block_size) {
                         
$buffer['xor'] = substr($key$start) . $buffer['xor'];
                    }
                }
                break;
            case 
CRYPT_MODE_STREAM:
                
$plaintext $this->_decryptBlock($ciphertext);
                break;
        }
        return 
$this->paddable $this->_unpad($plaintext) : $plaintext;
    }

    
/**
     * OpenSSL CTR Processor
     *
     * PHP's OpenSSL bindings do not operate in continuous mode so we'll wrap around it. Since the keystream
     * for CTR is the same for both encrypting and decrypting this function is re-used by both Crypt_Base::encrypt()
     * and Crypt_Base::decrypt(). Also, OpenSSL doesn't implement CTR for all of it's symmetric ciphers so this
     * function will emulate CTR with ECB when necesary.
     *
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::decrypt()
     * @param String $plaintext
     * @param String $encryptIV
     * @param Array $buffer
     * @return String
     * @access private
     */
    
function _openssl_ctr_process($plaintext, &$encryptIV, &$buffer)
    {
        
$ciphertext '';

        
$block_size $this->block_size;
        
$key $this->key;

        if (
$this->openssl_emulate_ctr) {
            
$xor $encryptIV;
            if (
strlen($buffer['ciphertext'])) {
                for (
$i 0$i strlen($plaintext); $i+=$block_size) {
                    
$block substr($plaintext$i$block_size);
                    if (
strlen($block) > strlen($buffer['ciphertext'])) {
                        
$result openssl_encrypt($xor$this->cipher_name_openssl_ecb$key$this->openssl_options);
                        
$result = !defined('OPENSSL_RAW_DATA') ? substr($result0, -$this->block_size) : $result;
                        
$buffer['ciphertext'].= $result;
                    }
                    
$this->_increment_str($xor);
                    
$otp $this->_string_shift($buffer['ciphertext'], $block_size);
                    
$ciphertext.= $block $otp;
                }
            } else {
                for (
$i 0$i strlen($plaintext); $i+=$block_size) {
                    
$block substr($plaintext$i$block_size);
                    
$otp openssl_encrypt($xor$this->cipher_name_openssl_ecb$key$this->openssl_options);
                    
$otp = !defined('OPENSSL_RAW_DATA') ? substr($otp0, -$this->block_size) : $otp;
                    
$this->_increment_str($xor);
                    
$ciphertext.= $block $otp;
                }
            }
            if (
$this->continuousBuffer) {
                
$encryptIV $xor;
                if (
$start strlen($plaintext) % $block_size) {
                    
$buffer['ciphertext'] = substr($key$start) . $buffer['ciphertext'];
                }
            }

            return 
$ciphertext;
        }

        if (
strlen($buffer['ciphertext'])) {
            
$ciphertext $plaintext $this->_string_shift($buffer['ciphertext'], strlen($plaintext));
            
$plaintext substr($plaintextstrlen($ciphertext));

            if (!
strlen($plaintext)) {
                return 
$ciphertext;
            }
        }

        
$overflow strlen($plaintext) % $block_size;
        if (
$overflow) {
            
$plaintext2 $this->_string_pop($plaintext$overflow); // ie. trim $plaintext to a multiple of $block_size and put rest of $plaintext in $plaintext2
            
$encrypted openssl_encrypt($plaintext str_repeat(""$block_size), $this->cipher_name_openssl$key$this->openssl_options$encryptIV);
            
$temp $this->_string_pop($encrypted$block_size);
            
$ciphertext.= $encrypted . ($plaintext2 $temp);
            if (
$this->continuousBuffer) {
                
$buffer['ciphertext'] = substr($temp$overflow);
                
$encryptIV $temp;
            }
        } elseif (!
strlen($buffer['ciphertext'])) {
            
$ciphertext.= openssl_encrypt($plaintext str_repeat(""$block_size), $this->cipher_name_openssl$key$this->openssl_options$encryptIV);
            
$temp $this->_string_pop($ciphertext$block_size);
            if (
$this->continuousBuffer) {
                
$encryptIV $temp;
            }
        }
        if (
$this->continuousBuffer) {
            if (!
defined('OPENSSL_RAW_DATA')) {
                
$encryptIV.= openssl_encrypt(''$this->cipher_name_openssl_ecb$key$this->openssl_options);
            }
            
$encryptIV openssl_decrypt($encryptIV$this->cipher_name_openssl_ecb$key$this->openssl_options);
            if (
$overflow) {
                
$this->_increment_str($encryptIV);
            }
        }

        return 
$ciphertext;
    }

    
/**
     * OpenSSL OFB Processor
     *
     * PHP's OpenSSL bindings do not operate in continuous mode so we'll wrap around it. Since the keystream
     * for OFB is the same for both encrypting and decrypting this function is re-used by both Crypt_Base::encrypt()
     * and Crypt_Base::decrypt().
     *
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::decrypt()
     * @param String $plaintext
     * @param String $encryptIV
     * @param Array $buffer
     * @return String
     * @access private
     */
    
function _openssl_ofb_process($plaintext, &$encryptIV, &$buffer)
    {
        if (
strlen($buffer['xor'])) {
            
$ciphertext $plaintext $buffer['xor'];
            
$buffer['xor'] = substr($buffer['xor'], strlen($ciphertext));
            
$plaintext substr($plaintextstrlen($ciphertext));
        } else {
            
$ciphertext '';
        }

        
$block_size $this->block_size;

        
$len strlen($plaintext);
        
$key $this->key;
        
$overflow $len $block_size;

        if (
strlen($plaintext)) {
            if (
$overflow) {
                
$ciphertext.= openssl_encrypt(substr($plaintext0, -$overflow) . str_repeat(""$block_size), $this->cipher_name_openssl$key$this->openssl_options$encryptIV);
                
$xor $this->_string_pop($ciphertext$block_size);
                if (
$this->continuousBuffer) {
                    
$encryptIV $xor;
                }
                
$ciphertext.= $this->_string_shift($xor$overflow) ^ substr($plaintext, -$overflow);
                if (
$this->continuousBuffer) {
                    
$buffer['xor'] = $xor;
                }
            } else {
                
$ciphertext openssl_encrypt($plaintext$this->cipher_name_openssl$key$this->openssl_options$encryptIV);
                if (
$this->continuousBuffer) {
                    
$encryptIV substr($ciphertext, -$block_size) ^ substr($plaintext, -$block_size);
                }
            }
        }

        return 
$ciphertext;
    }

    
/**
     * phpseclib <-> OpenSSL Mode Mapper
     *
     * May need to be overwritten by classes extending this one in some cases
     *
     * @return Integer
     * @access private
     */
    
function _openssl_translate_mode()
    {
        switch (
$this->mode) {
            case 
CRYPT_MODE_ECB:
                return 
'ecb';
            case 
CRYPT_MODE_CBC:
                return 
'cbc';
            case 
CRYPT_MODE_CTR:
                return 
'ctr';
            case 
CRYPT_MODE_CFB:
                return 
'cfb';
            case 
CRYPT_MODE_OFB:
                return 
'ofb';
        }
    }

    
/**
     * Pad "packets".
     *
     * Block ciphers working by encrypting between their specified [$this->]block_size at a time
     * If you ever need to encrypt or decrypt something that isn't of the proper length, it becomes necessary to
     * pad the input so that it is of the proper length.
     *
     * Padding is enabled by default.  Sometimes, however, it is undesirable to pad strings.  Such is the case in SSH,
     * 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_Base::disablePadding()
     * @access public
     */
    
function enablePadding()
    {
        
$this->padding true;
    }

    
/**
     * Do not pad packets.
     *
     * @see Crypt_Base::enablePadding()
     * @access public
     */
    
function disablePadding()
    {
        
$this->padding false;
    }

    
/**
     * Treat consecutive "packets" as if they are a continuous buffer.
     *
     * Say you have a 32-byte plaintext $plaintext.  Using the default behavior, the two following code snippets
     * will yield different outputs:
     *
     * <code>
     *    echo $rijndael->encrypt(substr($plaintext,  0, 16));
     *    echo $rijndael->encrypt(substr($plaintext, 16, 16));
     * </code>
     * <code>
     *    echo $rijndael->encrypt($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>
     *    $rijndael->encrypt(substr($plaintext, 0, 16));
     *    echo $rijndael->decrypt($rijndael->encrypt(substr($plaintext, 16, 16)));
     * </code>
     * <code>
     *    echo $rijndael->decrypt($rijndael->encrypt(substr($plaintext, 16, 16)));
     * </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_*() 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::disableContinuousBuffer()
     * @access public
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function enableContinuousBuffer()
    {
        if (
$this->mode == CRYPT_MODE_ECB) {
            return;
        }

        
$this->continuousBuffer true;

        
$this->_setEngine();
    }

    
/**
     * Treat consecutive packets as if they are a discontinuous buffer.
     *
     * The default behavior.
     *
     * @see Crypt_Base::enableContinuousBuffer()
     * @access public
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function disableContinuousBuffer()
    {
        if (
$this->mode == CRYPT_MODE_ECB) {
            return;
        }
        if (!
$this->continuousBuffer) {
            return;
        }

        
$this->continuousBuffer false;
        
$this->changed true;

        
$this->_setEngine();
    }

    
/**
     * Test for engine validity
     *
     * @see Crypt_Base::Crypt_Base()
     * @param Integer $engine
     * @access public
     * @return Boolean
     */
    
function isValidEngine($engine)
    {
        switch (
$engine) {
            case 
CRYPT_ENGINE_OPENSSL:
                if (
$this->mode == CRYPT_MODE_STREAM && $this->continuousBuffer) {
                    return 
false;
                }
                
$this->openssl_emulate_ctr false;
                
$result $this->cipher_name_openssl &&
                          
extension_loaded('openssl') &&
                          
// PHP 5.3.0 - 5.3.2 did not let you set IV's
                          
version_compare(PHP_VERSION'5.3.3''>=');
                if (!
$result) {
                    return 
false;
                }

                
// prior to PHP 5.4.0 OPENSSL_RAW_DATA and OPENSSL_ZERO_PADDING were not defined. instead of expecting an integer
                // $options openssl_encrypt expected a boolean $raw_data.
                
if (!defined('OPENSSL_RAW_DATA')) {
                    
$this->openssl_options true;
                } else {
                    
$this->openssl_options OPENSSL_RAW_DATA OPENSSL_ZERO_PADDING;
                }

                
$methods openssl_get_cipher_methods();
                if (
in_array($this->cipher_name_openssl$methods)) {
                    return 
true;
                }
                
// not all of openssl's symmetric cipher's support ctr. for those
                // that don't we'll emulate it
                
switch ($this->mode) {
                    case 
CRYPT_MODE_CTR:
                        if (
in_array($this->cipher_name_openssl_ecb$methods)) {
                            
$this->openssl_emulate_ctr true;
                            return 
true;
                        }
                }
                return 
false;
            case 
CRYPT_ENGINE_MCRYPT:
                return 
$this->cipher_name_mcrypt &&
                       
extension_loaded('mcrypt') &&
                       
in_array($this->cipher_name_mcryptmcrypt_list_algorithms());
            case 
CRYPT_ENGINE_INTERNAL:
                return 
true;
        }

        return 
false;
    }

    
/**
     * Sets the preferred crypt engine
     *
     * Currently, $engine could be:
     *
     * - CRYPT_ENGINE_OPENSSL  [very fast]
     *
     * - CRYPT_ENGINE_MCRYPT   [fast]
     *
     * - CRYPT_ENGINE_INTERNAL [slow]
     *
     * If the preferred crypt engine is not available the fastest available one will be used
     *
     * @see Crypt_Base::Crypt_Base()
     * @param Integer $engine
     * @access public
     */
    
function setPreferredEngine($engine)
    {
        switch (
$engine) {
            
//case CRYPT_ENGINE_OPENSSL:
            
case CRYPT_ENGINE_MCRYPT:
            case 
CRYPT_ENGINE_INTERNAL:
                
$this->preferredEngine $engine;
                break;
            default:
                
$this->preferredEngine CRYPT_ENGINE_OPENSSL;
        }

        
$this->_setEngine();
    }

    
/**
     * Returns the engine currently being utilized
     *
     * @see Crypt_Base::_setEngine()
     * @access public
     */
    
function getEngine()
    {
        return 
$this->engine;
    }

    
/**
     * Sets the engine as appropriate
     *
     * @see Crypt_Base::Crypt_Base()
     * @access private
     */
    
function _setEngine()
    {
        
$this->engine null;

        
$candidateEngines = array(
            
$this->preferredEngine,
            
CRYPT_ENGINE_OPENSSL,
            
CRYPT_ENGINE_MCRYPT
        
);
        foreach (
$candidateEngines as $engine) {
            if (
$this->isValidEngine($engine)) {
                
$this->engine $engine;
                break;
            }
        }
        if (!
$this->engine) {
            
$this->engine CRYPT_ENGINE_INTERNAL;
        }

        if (
$this->engine != CRYPT_ENGINE_MCRYPT && $this->enmcrypt) {
            
// Closing the current mcrypt resource(s). _mcryptSetup() will, if needed,
            // (re)open them with the module named in $this->cipher_name_mcrypt
            
mcrypt_module_close($this->enmcrypt);
            
mcrypt_module_close($this->demcrypt);
            
$this->enmcrypt null;
            
$this->demcrypt null;

            if (
$this->ecb) {
                
mcrypt_module_close($this->ecb);
                
$this->ecb null;
            }
        }

        
$this->changed true;
    }

    
/**
     * Encrypts a block
     *
     * @access private
     * @param String $in
     * @return String
     * @internal Must be extended by the child Crypt_* class
     */
    
function _encryptBlock($in)
    {
        
user_error((version_compare(PHP_VERSION'5.0.0''>=')  ? __METHOD__ __FUNCTION__)  . '() must extend by class ' get_class($this), E_USER_ERROR);
    }

    
/**
     * Decrypts a block
     *
     * @access private
     * @param String $in
     * @return String
     * @internal Must be extended by the child Crypt_* class
     */
    
function _decryptBlock($in)
    {
        
user_error((version_compare(PHP_VERSION'5.0.0''>=')  ? __METHOD__ __FUNCTION__)  . '() must extend by class ' get_class($this), E_USER_ERROR);
    }

    
/**
     * Setup the key (expansion)
     *
     * Only used if $engine == CRYPT_ENGINE_INTERNAL
     *
     * @see Crypt_Base::_setup()
     * @access private
     * @internal Must be extended by the child Crypt_* class
     */
    
function _setupKey()
    {
        
user_error((version_compare(PHP_VERSION'5.0.0''>=')  ? __METHOD__ __FUNCTION__)  . '() must extend by class ' get_class($this), E_USER_ERROR);
    }

    
/**
     * Setup the CRYPT_ENGINE_INTERNAL $engine
     *
     * (re)init, if necessary, the internal cipher $engine and flush all $buffers
     * Used (only) if $engine == CRYPT_ENGINE_INTERNAL
     *
     * _setup() will be called each time if $changed === true
     * typically this happens when using one or more of following public methods:
     *
     * - setKey()
     *
     * - setIV()
     *
     * - disableContinuousBuffer()
     *
     * - First run of encrypt() / decrypt() with no init-settings
     *
     * @see setKey()
     * @see setIV()
     * @see disableContinuousBuffer()
     * @access private
     * @internal _setup() is always called before en/decryption.
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function _setup()
    {
        
$this->_clearBuffers();
        
$this->_setupKey();

        if (
$this->use_inline_crypt) {
            
$this->_setupInlineCrypt();
        }
    }

    
/**
     * Setup the CRYPT_ENGINE_MCRYPT $engine
     *
     * (re)init, if necessary, the (ext)mcrypt resources and flush all $buffers
     * Used (only) if $engine = CRYPT_ENGINE_MCRYPT
     *
     * _setupMcrypt() will be called each time if $changed === true
     * typically this happens when using one or more of following public methods:
     *
     * - setKey()
     *
     * - setIV()
     *
     * - disableContinuousBuffer()
     *
     * - First run of encrypt() / decrypt()
     *
     * @see setKey()
     * @see setIV()
     * @see disableContinuousBuffer()
     * @access private
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function _setupMcrypt()
    {
        
$this->_clearBuffers();
        
$this->enchanged $this->dechanged true;

        if (!isset(
$this->enmcrypt)) {
            static 
$mcrypt_modes = array(
                
CRYPT_MODE_CTR    => 'ctr',
                
CRYPT_MODE_ECB    => MCRYPT_MODE_ECB,
                
CRYPT_MODE_CBC    => MCRYPT_MODE_CBC,
                
CRYPT_MODE_CFB    => 'ncfb',
                
CRYPT_MODE_OFB    => MCRYPT_MODE_NOFB,
                
CRYPT_MODE_STREAM => MCRYPT_MODE_STREAM,
            );

            
$this->demcrypt mcrypt_module_open($this->cipher_name_mcrypt''$mcrypt_modes[$this->mode], '');
            
$this->enmcrypt mcrypt_module_open($this->cipher_name_mcrypt''$mcrypt_modes[$this->mode], '');

            
// we need the $ecb mcrypt resource (only) in MODE_CFB with enableContinuousBuffer()
            // to workaround mcrypt's broken ncfb implementation in buffered mode
            // see: {@link http://phpseclib.sourceforge.net/cfb-demo.phps}
            
if ($this->mode == CRYPT_MODE_CFB) {
                
$this->ecb mcrypt_module_open($this->cipher_name_mcrypt''MCRYPT_MODE_ECB'');
            }

        } 
// else should mcrypt_generic_deinit be called?

        
if ($this->mode == CRYPT_MODE_CFB) {
            
mcrypt_generic_init($this->ecb$this->keystr_repeat(""$this->block_size));
        }
    }

    
/**
     * Pads a string
     *
     * Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize.
     * $this->block_size - (strlen($text) % $this->block_size) bytes are added, each of which is equal to
     * chr($this->block_size - (strlen($text) % $this->block_size)
     *
     * 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_Base::_unpad()
     * @param String $text
     * @access private
     * @return String
     */
    
function _pad($text)
    {
        
$length strlen($text);

        if (!
$this->padding) {
            if (
$length $this->block_size == 0) {
                return 
$text;
            } else {
                
user_error("The plaintext's length ($length) is not a multiple of the block size ({$this->block_size})");
                
$this->padding true;
            }
        }

        
$pad $this->block_size - ($length $this->block_size);

        return 
str_pad($text$length $padchr($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_Base::_pad()
     * @param String $text
     * @access private
     * @return String
     */
    
function _unpad($text)
    {
        if (!
$this->padding) {
            return 
$text;
        }

        
$length ord($text[strlen($text) - 1]);

        if (!
$length || $length $this->block_size) {
            return 
false;
        }

        return 
substr($text0, -$length);
    }

    
/**
     * Clears internal buffers
     *
     * Clearing/resetting the internal buffers is done everytime
     * after disableContinuousBuffer() or on cipher $engine (re)init
     * ie after setKey() or setIV()
     *
     * @access public
     * @internal Could, but not must, extend by the child Crypt_* class
     */
    
function _clearBuffers()
    {
        
$this->enbuffer $this->debuffer = array('ciphertext' => '''xor' => '''pos' => 0'enmcrypt_init' => true);

        
// mcrypt's handling of invalid's $iv:
        // $this->encryptIV = $this->decryptIV = strlen($this->iv) == $this->block_size ? $this->iv : str_repeat("", $this->block_size);
        
$this->encryptIV $this->decryptIV str_pad(substr($this->iv0$this->block_size), $this->block_size"");
    }

    
/**
     * String Shift
     *
     * Inspired by array_shift
     *
     * @param String $string
     * @param optional Integer $index
     * @access private
     * @return String
     */
    
function _string_shift(&$string$index 1)
    {
        
$substr substr($string0$index);
        
$string substr($string$index);
        return 
$substr;
    }

    
/**
     * String Pop
     *
     * Inspired by array_pop
     *
     * @param String $string
     * @param optional Integer $index
     * @access private
     * @return String
     */
    
function _string_pop(&$string$index 1)
    {
        
$substr substr($string, -$index);
        
$string substr($string0, -$index);
        return 
$substr;
    }

    
/**
     * Increment the current string
     *
     * @see Crypt_Base::decrypt()
     * @see Crypt_Base::encrypt()
     * @param String $var
     * @access private
     */
    
function _increment_str(&$var)
    {
        for (
$i 4$i <= strlen($var); $i+= 4) {
            
$temp substr($var, -$i4);
            switch (
$temp) {
                case 
"xFFxFFxFFxFF":
                    
$var substr_replace($var"x00x00x00x00", -$i4);
                    break;
                case 
"x7FxFFxFFxFF":
                    
$var substr_replace($var"x80x00x00x00", -$i4);
                    return;
                default:
                    
$temp unpack('Nnum'$temp);
                    
$var substr_replace($varpack('N'$temp['num'] + 1), -$i4);
                    return;
            }
        }

        
$remainder strlen($var) % 4;

        if (
$remainder == 0) {
            return;
        }

        
$temp unpack('Nnum'str_pad(substr($var0$remainder), 4""STR_PAD_LEFT));
        
$temp substr(pack('N'$temp['num'] + 1), -$remainder);
        
$var substr_replace($var$temp0$remainder);
    }

    
/**
     * Setup the performance-optimized function for de/encrypt()
     *
     * Stores the created (or existing) callback function-name
     * in $this->inline_crypt
     *
     * Internally for phpseclib developers:
     *
     *     _setupInlineCrypt() would be called only if:
     *
     *     - $engine == CRYPT_ENGINE_INTERNAL and
     *
     *     - $use_inline_crypt === true
     *
     *     - each time on _setup(), after(!) _setupKey()
     *
     *
     *     This ensures that _setupInlineCrypt() has always a
     *     full ready2go initializated internal cipher $engine state
     *     where, for example, the keys allready expanded,
     *     keys/block_size calculated and such.
     *
     *     It is, each time if called, the responsibility of _setupInlineCrypt():
     *
     *     - to set $this->inline_crypt to a valid and fully working callback function
     *       as a (faster) replacement for encrypt() / decrypt()
     *
     *     - NOT to create unlimited callback functions (for memory reasons!)
     *       no matter how often _setupInlineCrypt() would be called. At some
     *       point of amount they must be generic re-useable.
     *
     *     - the code of _setupInlineCrypt() it self,
     *       and the generated callback code,
     *       must be, in following order:
     *       - 100% safe
     *       - 100% compatible to encrypt()/decrypt()
     *       - using only php5+ features/lang-constructs/php-extensions if
     *         compatibility (down to php4) or fallback is provided
     *       - readable/maintainable/understandable/commented and... not-cryptic-styled-code :-)
     *       - >= 10% faster than encrypt()/decrypt() [which is, by the way,
     *         the reason for the existence of _setupInlineCrypt() :-)]
     *       - memory-nice
     *       - short (as good as possible)
     *
     * Note: - _setupInlineCrypt() is using _createInlineCryptFunction() to create the full callback function code.
     *       - In case of using inline crypting, _setupInlineCrypt() must extend by the child Crypt_* class.
     *       - The following variable names are reserved:
     *         - $_*  (all variable names prefixed with an underscore)
     *         - $self (object reference to it self. Do not use $this, but $self instead)
     *         - $in (the content of $in has to en/decrypt by the generated code)
     *       - The callback function should not use the 'return' statement, but en/decrypt'ing the content of $in only
     *
     *
     * @see Crypt_Base::_setup()
     * @see Crypt_Base::_createInlineCryptFunction()
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::decrypt()
     * @access private
     * @internal If a Crypt_* class providing inline crypting it must extend _setupInlineCrypt()
     */
    
function _setupInlineCrypt()
    {
        
// If, for any reason, an extending Crypt_Base() Crypt_* class
        // not using inline crypting then it must be ensured that: $this->use_inline_crypt = false
        // ie in the class var declaration of $use_inline_crypt in general for the Crypt_* class,
        // in the constructor at object instance-time
        // or, if it's runtime-specific, at runtime

        
$this->use_inline_crypt false;
    }

    
/**
     * Creates the performance-optimized function for en/decrypt()
     *
     * Internally for phpseclib developers:
     *
     *    _createInlineCryptFunction():
     *
     *    - merge the $cipher_code [setup'ed by _setupInlineCrypt()]
     *      with the current [$this->]mode of operation code
     *
     *    - create the $inline function, which called by encrypt() / decrypt()
     *      as its replacement to speed up the en/decryption operations.
     *
     *    - return the name of the created $inline callback function
     *
     *    - used to speed up en/decryption
     *
     *
     *
     *    The main reason why can speed up things [up to 50%] this way are:
     *
     *    - using variables more effective then regular.
     *      (ie no use of expensive arrays but integers $k_0, $k_1 ...
     *      or even, for example, the pure $key[] values hardcoded)
     *
     *    - avoiding 1000's of function calls of ie _encryptBlock()
     *      but inlining the crypt operations.
     *      in the mode of operation for() loop.
     *
     *    - full loop unroll the (sometimes key-dependent) rounds
     *      avoiding this way ++$i counters and runtime-if's etc...
     *
     *    The basic code architectur of the generated $inline en/decrypt()
     *    lambda function, in pseudo php, is:
     *
     *    <code>
     *    +----------------------------------------------------------------------------------------------+
     *    | callback $inline = create_function:                                                          |
     *    | lambda_function_0001_crypt_ECB($action, $text)                                               |
     *    | {                                                                                            |
     *    |     INSERT PHP CODE OF:                                                                      |
     *    |     $cipher_code['init_crypt'];                  // general init code.                       |
     *    |                                                  // ie: $sbox'es declarations used for       |
     *    |                                                  //     encrypt and decrypt'ing.             |
     *    |                                                                                              |
     *    |     switch ($action) {                                                                       |
     *    |         case 'encrypt':                                                                      |
     *    |             INSERT PHP CODE OF:                                                              |
     *    |             $cipher_code['init_encrypt'];       // encrypt sepcific init code.               |
     *    |                                                    ie: specified $key or $box                |
     *    |                                                        declarations for encrypt'ing.         |
     *    |                                                                                              |
     *    |             foreach ($ciphertext) {                                                          |
     *    |                 $in = $block_size of $ciphertext;                                            |
     *    |                                                                                              |
     *    |                 INSERT PHP CODE OF:                                                          |
     *    |                 $cipher_code['encrypt_block'];  // encrypt's (string) $in, which is always:  |
     *    |                                                 // strlen($in) == $this->block_size          |
     *    |                                                 // here comes the cipher algorithm in action |
     *    |                                                 // for encryption.                           |
     *    |                                                 // $cipher_code['encrypt_block'] has to      |
     *    |                                                 // encrypt the content of the $in variable   |
     *    |                                                                                              |
     *    |                 $plaintext .= $in;                                                           |
     *    |             }                                                                                |
     *    |             return $plaintext;                                                               |
     *    |                                                                                              |
     *    |         case 'decrypt':                                                                      |
     *    |             INSERT PHP CODE OF:                                                              |
     *    |             $cipher_code['init_decrypt'];       // decrypt sepcific init code                |
     *    |                                                    ie: specified $key or $box                |
     *    |                                                        declarations for decrypt'ing.         |
     *    |             foreach ($plaintext) {                                                           |
     *    |                 $in = $block_size of $plaintext;                                             |
     *    |                                                                                              |
     *    |                 INSERT PHP CODE OF:                                                          |
     *    |                 $cipher_code['decrypt_block'];  // decrypt's (string) $in, which is always   |
     *    |                                                 // strlen($in) == $this->block_size          |
     *    |                                                 // here comes the cipher algorithm in action |
     *    |                                                 // for decryption.                           |
     *    |                                                 // $cipher_code['decrypt_block'] has to      |
     *    |                                                 // decrypt the content of the $in variable   |
     *    |                 $ciphertext .= $in;                                                          |
     *    |             }                                                                                |
     *    |             return $ciphertext;                                                              |
     *    |     }                                                                                        |
     *    | }                                                                                            |
     *    +----------------------------------------------------------------------------------------------+
     *    </code>
     *
     *    See also the Crypt_*::_setupInlineCrypt()'s for
     *    productive inline $cipher_code's how they works.
     *
     *    Structure of:
     *    <code>
     *    $cipher_code = array(
     *        'init_crypt'    => (string) '', // optional
     *        'init_encrypt'  => (string) '', // optional
     *        'init_decrypt'  => (string) '', // optional
     *        'encrypt_block' => (string) '', // required
     *        'decrypt_block' => (string) ''  // required
     *    );
     *    </code>
     *
     * @see Crypt_Base::_setupInlineCrypt()
     * @see Crypt_Base::encrypt()
     * @see Crypt_Base::decrypt()
     * @param Array $cipher_code
     * @access private
     * @return String (the name of the created callback function)
     */
    
function _createInlineCryptFunction($cipher_code)
    {
        
$block_size $this->block_size;

        
// optional
        
$init_crypt    = isset($cipher_code['init_crypt'])    ? $cipher_code['init_crypt']    : '';
        
$init_encrypt  = isset($cipher_code['init_encrypt'])  ? $cipher_code['init_encrypt']  : '';
        
$init_decrypt  = isset($cipher_code['init_decrypt'])  ? $cipher_code['init_decrypt']  : '';
        
// required
        
$encrypt_block $cipher_code['encrypt_block'];
        
$decrypt_block $cipher_code['decrypt_block'];

        
// Generating mode of operation inline code,
        // merged with the $cipher_code algorithm
        // for encrypt- and decryption.
        
switch ($this->mode) {
            case 
CRYPT_MODE_ECB:
                
$encrypt $init_encrypt '
                    $_ciphertext = "";
                    $_plaintext_len = strlen($_text);

                    for ($_i = 0; $_i < $_plaintext_len; $_i+= '
.$block_size.') {
                        $in = substr($_text, $_i, '
.$block_size.');
                        '
.$encrypt_block.'
                        $_ciphertext.= $in;
                    }

                    return $_ciphertext;
                    '
;

                
$decrypt $init_decrypt '
                    $_plaintext = "";
                    $_text = str_pad($_text, strlen($_text) + ('
.$block_size.' - strlen($_text) % '.$block_size.') % '.$block_size.', chr(0));
                    $_ciphertext_len = strlen($_text);

                    for ($_i = 0; $_i < $_ciphertext_len; $_i+= '
.$block_size.') {
                        $in = substr($_text, $_i, '
.$block_size.');
                        '
.$decrypt_block.'
                        $_plaintext.= $in;
                    }

                    return $self->_unpad($_plaintext);
                    '
;
                break;
            case 
CRYPT_MODE_CTR:
                
$encrypt $init_encrypt '
                    $_ciphertext = "";
                    $_plaintext_len = strlen($_text);
                    $_xor = $self->encryptIV;
                    $_buffer = &$self->enbuffer;
                    if (strlen($_buffer["ciphertext"])) {
                        for ($_i = 0; $_i < $_plaintext_len; $_i+= '
.$block_size.') {
                            $_block = substr($_text, $_i, '
.$block_size.');
                            if (strlen($_block) > strlen($_buffer["ciphertext"])) {
                                $in = $_xor;
                                '
.$encrypt_block.'
                                $self->_increment_str($_xor);
                                $_buffer["ciphertext"].= $in;
                            }
                            $_key = $self->_string_shift($_buffer["ciphertext"], '
.$block_size.');
                            $_ciphertext.= $_block ^ $_key;
                        }
                    } else {
                        for ($_i = 0; $_i < $_plaintext_len; $_i+= '
.$block_size.') {
                            $_block = substr($_text, $_i, '
.$block_size.');
                            $in = $_xor;
                            '
.$encrypt_block.'
                            $self->_increment_str($_xor);
                            $_key = $in;
                            $_ciphertext.= $_block ^ $_key;
                        }
                    }
                    if ($self->continuousBuffer) {
                        $self->encryptIV = $_xor;
                        if ($_start = $_plaintext_len % '
.$block_size.') {
                            $_buffer["ciphertext"] = substr($_key, $_start) . $_buffer["ciphertext"];
                        }
                    }

                    return $_ciphertext;
                '
;

                
$decrypt $init_encrypt '
                    $_plaintext = "";
                    $_ciphertext_len = strlen($_text);
                    $_xor = $self->decryptIV;
                    $_buffer = &$self->debuffer;

                    if (strlen($_buffer["ciphertext"])) {
                        for ($_i = 0; $_i < $_ciphertext_len; $_i+= '
.$block_size.') {
                            $_block = substr($_text, $_i, '
.$block_size.');
                            if (strlen($_block) > strlen($_buffer["ciphertext"])) {
                                $in = $_xor;
                                '
.$encrypt_block.'
                                $self->_increment_str($_xor);
                                $_buffer["ciphertext"].= $in;
                            }
                            $_key = $self->_string_shift($_buffer["ciphertext"], '
.$block_size.');
                            $_plaintext.= $_block ^ $_key;
                        }
                    } else {
                        for ($_i = 0; $_i < $_ciphertext_len; $_i+= '
.$block_size.') {
                            $_block = substr($_text, $_i, '
.$block_size.');
                            $in = $_xor;
                            '
.$encrypt_block.'
                            $self->_increment_str($_xor);
                            $_key = $in;
                            $_plaintext.= $_block ^ $_key;
                        }
                    }
                    if ($self->continuousBuffer) {
                        $self->decryptIV = $_xor;
                        if ($_start = $_ciphertext_len % '
.$block_size.') {
                            $_buffer["ciphertext"] = substr($_key, $_start) . $_buffer["ciphertext"];
                        }
                    }

                    return $_plaintext;
                    '
;
                break;
            case 
CRYPT_MODE_CFB:
                
$encrypt $init_encrypt '
                    $_ciphertext = "";
                    $_buffer = &$self->enbuffer;

                    if ($self->continuousBuffer) {
                        $_iv = &$self->encryptIV;
                        $_pos = &$_buffer["pos"];
                    } else {
                        $_iv = $self->encryptIV;
                        $_pos = 0;
                    }
                    $_len = strlen($_text);
                    $_i = 0;
                    if ($_pos) {
                        $_orig_pos = $_pos;
                        $_max = '
.$block_size.' - $_pos;
                        if ($_len >= $_max) {
                            $_i = $_max;
                            $_len-= $_max;
                            $_pos = 0;
                        } else {
                            $_i = $_len;
                            $_pos+= $_len;
                            $_len = 0;
                        }
                        $_ciphertext = substr($_iv, $_orig_pos) ^ $_text;
                        $_iv = substr_replace($_iv, $_ciphertext, $_orig_pos, $_i);
                    }
                    while ($_len >= '
.$block_size.') {
                        $in = $_iv;
                        '
.$encrypt_block.';
                        $_iv = $in ^ substr($_text, $_i, '
.$block_size.');
                        $_ciphertext.= $_iv;
                        $_len-= '
.$block_size.';
                        $_i+= '
.$block_size.';
                    }
                    if ($_len) {
                        $in = $_iv;
                        '
.$encrypt_block.'
                        $_iv = $in;
                        $_block = $_iv ^ substr($_text, $_i);
                        $_iv = substr_replace($_iv, $_block, 0, $_len);
                        $_ciphertext.= $_block;
                        $_pos = $_len;
                    }
                    return $_ciphertext;
                '
;

                
$decrypt $init_encrypt '
                    $_plaintext = "";
                    $_buffer = &$self->debuffer;

                    if ($self->continuousBuffer) {
                        $_iv = &$self->decryptIV;
                        $_pos = &$_buffer["pos"];
                    } else {
                        $_iv = $self->decryptIV;
                        $_pos = 0;
                    }
                    $_len = strlen($_text);
                    $_i = 0;
                    if ($_pos) {
                        $_orig_pos = $_pos;
                        $_max = '
.$block_size.' - $_pos;
                        if ($_len >= $_max) {
                            $_i = $_max;
                            $_len-= $_max;
                            $_pos = 0;
                        } else {
                            $_i = $_len;
                            $_pos+= $_len;
                            $_len = 0;
                        }
                        $_plaintext = substr($_iv, $_orig_pos) ^ $_text;
                        $_iv = substr_replace($_iv, substr($_text, 0, $_i), $_orig_pos, $_i);
                    }
                    while ($_len >= '
.$block_size.') {
                        $in = $_iv;
                        '
.$encrypt_block.'
                        $_iv = $in;
                        $cb = substr($_text, $_i, '
.$block_size.');
                        $_plaintext.= $_iv ^ $cb;
                        $_iv = $cb;
                        $_len-= '
.$block_size.';
                        $_i+= '
.$block_size.';
                    }
                    if ($_len) {
                        $in = $_iv;
                        '
.$encrypt_block.'
                        $_iv = $in;
                        $_plaintext.= $_iv ^ substr($_text, $_i);
                        $_iv = substr_replace($_iv, substr($_text, $_i), 0, $_len);
                        $_pos = $_len;
                    }

                    return $_plaintext;
                    '
;
                break;
            case 
CRYPT_MODE_OFB:
                
$encrypt $init_encrypt '
                    $_ciphertext = "";
                    $_plaintext_len = strlen($_text);
                    $_xor = $self->encryptIV;
                    $_buffer = &$self->enbuffer;

                    if (strlen($_buffer["xor"])) {
                        for ($_i = 0; $_i < $_plaintext_len; $_i+= '
.$block_size.') {
                            $_block = substr($_text, $_i, '
.$block_size.');
                            if (strlen($_block) > strlen($_buffer["xor"])) {
                                $in = $_xor;
                                '
.$encrypt_block.'
                                $_xor = $in;
                                $_buffer["xor"].= $_xor;
                            }
                            $_key = $self->_string_shift($_buffer["xor"], '
.$block_size.');
                            $_ciphertext.= $_block ^ $_key;
                        }
                    } else {
                        for ($_i = 0; $_i < $_plaintext_len; $_i+= '
.$block_size.') {
                            $in = $_xor;
                            '
.$encrypt_block.'
                            $_xor = $in;
                            $_ciphertext.= substr($_text, $_i, '
.$block_size.') ^ $_xor;
                        }
                        $_key = $_xor;
                    }
                    if ($self->continuousBuffer) {
                        $self->encryptIV = $_xor;
                        if ($_start = $_plaintext_len % '
.$block_size.') {
                             $_buffer["xor"] = substr($_key, $_start) . $_buffer["xor"];
                        }
                    }
                    return $_ciphertext;
                    '
;

                
$decrypt $init_encrypt '
                    $_plaintext = "";
                    $_ciphertext_len = strlen($_text);
                    $_xor = $self->decryptIV;
                    $_buffer = &$self->debuffer;

                    if (strlen($_buffer["xor"])) {
                        for ($_i = 0; $_i < $_ciphertext_len; $_i+= '
.$block_size.') {
                            $_block = substr($_text, $_i, '
.$block_size.');
                            if (strlen($_block) > strlen($_buffer["xor"])) {
                                $in = $_xor;
                                '
.$encrypt_block.'
                                $_xor = $in;
                                $_buffer["xor"].= $_xor;
                            }
                            $_key = $self->_string_shift($_buffer["xor"], '
.$block_size.');
                            $_plaintext.= $_block ^ $_key;
                        }
                    } else {
                        for ($_i = 0; $_i < $_ciphertext_len; $_i+= '
.$block_size.') {
                            $in = $_xor;
                            '
.$encrypt_block.'
                            $_xor = $in;
                            $_plaintext.= substr($_text, $_i, '
.$block_size.') ^ $_xor;
                        }
                        $_key = $_xor;
                    }
                    if ($self->continuousBuffer) {
                        $self->decryptIV = $_xor;
                        if ($_start = $_ciphertext_len % '
.$block_size.') {
                             $_buffer["xor"] = substr($_key, $_start) . $_buffer["xor"];
                        }
                    }
                    return $_plaintext;
                    '
;
                break;
            case 
CRYPT_MODE_STREAM:
                
$encrypt $init_encrypt '
                    $_ciphertext = "";
                    '
.$encrypt_block.'
                    return $_ciphertext;
                    '
;
                
$decrypt $init_decrypt '
                    $_plaintext = "";
                    '
.$decrypt_block.'
                    return $_plaintext;
                    '
;
                break;
            
// case CRYPT_MODE_CBC:
            
default:
                
$encrypt $init_encrypt '
                    $_ciphertext = "";
                    $_plaintext_len = strlen($_text);

                    $in = $self->encryptIV;

                    for ($_i = 0; $_i < $_plaintext_len; $_i+= '
.$block_size.') {
                        $in = substr($_text, $_i, '
.$block_size.') ^ $in;
                        '
.$encrypt_block.'
                        $_ciphertext.= $in;
                    }

                    if ($self->continuousBuffer) {
                        $self->encryptIV = $in;
                    }

                    return $_ciphertext;
                    '
;

                
$decrypt $init_decrypt '
                    $_plaintext = "";
                    $_text = str_pad($_text, strlen($_text) + ('
.$block_size.' - strlen($_text) % '.$block_size.') % '.$block_size.', chr(0));
                    $_ciphertext_len = strlen($_text);

                    $_iv = $self->decryptIV;

                    for ($_i = 0; $_i < $_ciphertext_len; $_i+= '
.$block_size.') {
                        $in = $_block = substr($_text, $_i, '
.$block_size.');
                        '
.$decrypt_block.'
                        $_plaintext.= $in ^ $_iv;
                        $_iv = $_block;
                    }

                    if ($self->continuousBuffer) {
                        $self->decryptIV = $_iv;
                    }

                    return $self->_unpad($_plaintext);
                    '
;
                break;
        }

        
// Create the $inline function and return its name as string. Ready to run!
        
return create_function('$_action, &$self, $_text'$init_crypt 'if ($_action == "encrypt") { ' $encrypt ' } else { ' $decrypt ' }');
    }

    
/**
     * Holds the lambda_functions table (classwide)
     *
     * Each name of the lambda function, created from
     * _setupInlineCrypt() && _createInlineCryptFunction()
     * is stored, classwide (!), here for reusing.
     *
     * The string-based index of $function is a classwide
     * uniqe value representing, at least, the $mode of
     * operation (or more... depends of the optimizing level)
     * for which $mode the lambda function was created.
     *
     * @access private
     * @return Array &$functions
     */
    
function &_getLambdaFunctions()
    {
        static 
$functions = array();
        return 
$functions;
    }

    
/**
     * Generates a digest from $bytes
     *
     * @see _setupInlineCrypt()
     * @access private
     * @param $bytes
     * @return String
     */
    
function _hashInlineCryptFunction($bytes)
    {
        if (!
defined('CRYPT_BASE_WHIRLPOOL_AVAILABLE')) {
            
define('CRYPT_BASE_WHIRLPOOL_AVAILABLE', (bool)(extension_loaded('hash') && in_array('whirlpool'hash_algos())));
        }

        
$result '';
        
$hash $bytes;

        switch (
true) {
            case 
CRYPT_BASE_WHIRLPOOL_AVAILABLE:
                foreach (
str_split($bytes64) as $t) {
                    
$hash hash('whirlpool'$hashtrue);
                    
$result .= $t $hash;
                }
                return 
$result hash('whirlpool'$hashtrue);
            default:
                
$len strlen($bytes);
                for (
$i 0$i $len$i+=20) {
                    
$t substr($bytes$i20);
                    
$hash pack('H*'sha1($hash));
                    
$result .= $t $hash;
                }
                return 
$result pack('H*'sha1($hash));
        }
    }
}
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