LDAPAccountManager/lam/lib/3rdParty/phpseclib/Crypt/Rijndael.php

<?php

/**
 * Pure-PHP implementation of Rijndael.
 *
 * Uses mcrypt, if available/possible, and an internal implementation, otherwise.
 *
 * PHP versions 4 and 5
 *
 * If {@link Crypt_Rijndael::setBlockLength() setBlockLength()} isn't called, it'll be assumed to be 128 bits.  If
 * {@link Crypt_Rijndael::setKeyLength() setKeyLength()} isn't called, it'll be calculated from
 * {@link Crypt_Rijndael::setKey() setKey()}.  ie. if the key is 128-bits, the key length will be 128-bits.  If it's
 * 136-bits it'll be null-padded to 192-bits and 192 bits will be the key length until
 * {@link Crypt_Rijndael::setKey() setKey()} is called, again, at which point, it'll be recalculated.
 *
 * Not all Rijndael implementations may support 160-bits or 224-bits as the block length / key length.  mcrypt, for example,
 * does not.  AES, itself, only supports block lengths of 128 and key lengths of 128, 192, and 256.
 * {@link http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=10 Rijndael-ammended.pdf#page=10} defines the
 * algorithm for block lengths of 192 and 256 but not for block lengths / key lengths of 160 and 224.  Indeed, 160 and 224
 * are first defined as valid key / block lengths in
 * {@link http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=44 Rijndael-ammended.pdf#page=44}:
 * Extensions: Other block and Cipher Key lengths.
 * Note: Use of 160/224-bit Keys must be explicitly set by setKeyLength(160) respectively setKeyLength(224).
 *
 * {@internal The variable names are the same as those in
 * {@link http://www.csrc.nist.gov/publications/fips/fips197/fips-197.pdf#page=10 fips-197.pdf#page=10}.}}
 *
 * Here's a short example of how to use this library:
 * <code>
 * <?php
 *    include 'Crypt/Rijndael.php';
 *
 *    $rijndael = new Crypt_Rijndael();
 *
 *    $rijndael->setKey('abcdefghijklmnop');
 *
 *    $size = 10 * 1024;
 *    $plaintext = '';
 *    for ($i = 0; $i < $size; $i++) {
 *        $plaintext.= 'a';
 *    }
 *
 *    echo $rijndael->decrypt($rijndael->encrypt($plaintext));
 * ?>
 * </code>
 *
 * 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_Rijndael
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2008 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

/**
 * Include Crypt_Base
 *
 * Base cipher class
 */
if (!class_exists('Crypt_Base')) {
    include_once 'Base.php';
}

/**#@+
 * @access public
 * @see Crypt_Rijndael::encrypt()
 * @see Crypt_Rijndael::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_RIJNDAEL_MODE_CTR', CRYPT_MODE_CTR);
/**
 * 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_RIJNDAEL_MODE_ECB', CRYPT_MODE_ECB);
/**
 * 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_RIJNDAEL_MODE_CBC', CRYPT_MODE_CBC);
/**
 * Encrypt / decrypt using the Cipher Feedback mode.
 *
 * @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Cipher_feedback_.28CFB.29
 */
define('CRYPT_RIJNDAEL_MODE_CFB', CRYPT_MODE_CFB);
/**
 * Encrypt / decrypt using the Cipher Feedback mode.
 *
 * @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Output_feedback_.28OFB.29
 */
define('CRYPT_RIJNDAEL_MODE_OFB', CRYPT_MODE_OFB);
/**#@-*/

/**
 * Pure-PHP implementation of Rijndael.
 *
 * @package Crypt_Rijndael
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class Crypt_Rijndael extends Crypt_Base
{
    /**
     * The default password key_size used by setPassword()
     *
     * @see Crypt_Base::password_key_size
     * @see Crypt_Base::setPassword()
     * @var Integer
     * @access private
     */
    var $password_key_size = 16;

    /**
     * The namespace used by the cipher for its constants.
     *
     * @see Crypt_Base::const_namespace
     * @var String
     * @access private
     */
    var $const_namespace = 'RIJNDAEL';

    /**
     * The mcrypt specific name of the cipher
     *
     * Mcrypt is useable for 128/192/256-bit $block_size/$key_size. For 160/224 not.
     * Crypt_Rijndael determines automatically whether mcrypt is useable
     * or not for the current $block_size/$key_size.
     * In case of, $cipher_name_mcrypt will be set dynamically at run time accordingly.
     *
     * @see Crypt_Base::cipher_name_mcrypt
     * @see Crypt_Base::engine
     * @see isValidEngine()
     * @var String
     * @access private
     */
    var $cipher_name_mcrypt = 'rijndael-128';

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

    /**
     * Has the key length explicitly been set or should it be derived from the key, itself?
     *
     * @see setKeyLength()
     * @var Boolean
     * @access private
     */
    var $explicit_key_length = false;

    /**
     * The Key Schedule
     *
     * @see _setup()
     * @var Array
     * @access private
     */
    var $w;

    /**
     * The Inverse Key Schedule
     *
     * @see _setup()
     * @var Array
     * @access private
     */
    var $dw;

    /**
     * The Block Length divided by 32
     *
     * @see setBlockLength()
     * @var Integer
     * @access private
     * @internal The max value is 256 / 32 = 8, the min value is 128 / 32 = 4.  Exists in conjunction with $block_size
     *    because the encryption / decryption / key schedule creation requires this number and not $block_size.  We could
     *    derive this from $block_size or vice versa, but that'd mean we'd have to do multiple shift operations, so in lieu
     *    of that, we'll just precompute it once.
     */
    var $Nb = 4;

    /**
     * The Key Length
     *
     * @see setKeyLength()
     * @var Integer
     * @access private
     * @internal The max value is 256 / 8 = 32, the min value is 128 / 8 = 16.  Exists in conjunction with $Nk
     *    because the encryption / decryption / key schedule creation requires this number and not $key_size.  We could
     *    derive this from $key_size or vice versa, but that'd mean we'd have to do multiple shift operations, so in lieu
     *    of that, we'll just precompute it once.
     */
    var $key_size = 16;

    /**
     * The Key Length divided by 32
     *
     * @see setKeyLength()
     * @var Integer
     * @access private
     * @internal The max value is 256 / 32 = 8, the min value is 128 / 32 = 4
     */
    var $Nk = 4;

    /**
     * The Number of Rounds
     *
     * @var Integer
     * @access private
     * @internal The max value is 14, the min value is 10.
     */
    var $Nr;

    /**
     * Shift offsets
     *
     * @var Array
     * @access private
     */
    var $c;

    /**
     * Holds the last used key- and block_size information
     *
     * @var Array
     * @access private
     */
    var $kl;

    /**
     * Default Constructor.
     *
     * Determines whether or not the mcrypt extension should be used.
     *
     * $mode could be:
     *
     * - CRYPT_RIJNDAEL_MODE_ECB
     *
     * - CRYPT_RIJNDAEL_MODE_CBC
     *
     * - CRYPT_RIJNDAEL_MODE_CTR
     *
     * - CRYPT_RIJNDAEL_MODE_CFB
     *
     * - CRYPT_RIJNDAEL_MODE_OFB
     *
     * If not explictly set, CRYPT_RIJNDAEL_MODE_CBC will be used.
     *
     * @see Crypt_Base::Crypt_Base()
     * @param optional Integer $mode
     * @access public
     */
    function Crypt_Rijndael($mode = CRYPT_RIJNDAEL_MODE_CBC)
    {
        parent::Crypt_Base($mode);
    }

    /**
     * Sets the key.
     *
     * Keys can be of any length.  Rijndael, itself, requires the use of a key that's between 128-bits and 256-bits long and
     * whose length is a multiple of 32.  If the key is less than 256-bits and the key length isn't set, we round the length
     * up to the closest valid key length, padding $key with null bytes.  If the key is more than 256-bits, we trim the
     * excess bits.
     *
     * If the key is not explicitly set, it'll be assumed to be all null bytes.
     *
     * Note: 160/224-bit keys must explicitly set by setKeyLength(), otherwise they will be round/pad up to 192/256 bits.
     *
     * @see Crypt_Base:setKey()
     * @see setKeyLength()
     * @access public
     * @param String $key
     */
    function setKey($key)
    {
        if (!$this->explicit_key_length) {
            $length = strlen($key);
            switch (true) {
                case $length <= 16:
                    $this->key_size = 16;
                    break;
                case $length <= 20:
                    $this->key_size = 20;
                    break;
                case $length <= 24:
                    $this->key_size = 24;
                    break;
                case $length <= 28:
                    $this->key_size = 28;
                    break;
                default:
                    $this->key_size = 32;
            }
        }
        parent::setKey($key);
    }

    /**
     * Sets the key length
     *
     * Valid key lengths are 128, 160, 192, 224, and 256.  If the length is less than 128, it will be rounded up to
     * 128.  If the length is greater than 128 and invalid, it will be rounded down to the closest valid amount.
     *
     * Note: phpseclib extends Rijndael (and AES) for using 160- and 224-bit keys but they are officially not defined
     *       and the most (if not all) implementations are not able using 160/224-bit keys but round/pad them up to
     *       192/256 bits as, for example, mcrypt will do.
     *
     *       That said, if you want be compatible with other Rijndael and AES implementations,
     *       you should not setKeyLength(160) or setKeyLength(224).
     *
     * Additional: In case of 160- and 224-bit keys, phpseclib will/can, for that reason, not use
     *             the mcrypt php extension, even if available.
     *             This results then in slower encryption.
     *
     * @access public
     * @param Integer $length
     */
    function setKeyLength($length)
    {
        switch (true) {
            case $length == 160:
                $this->key_size = 20;
                break;
            case $length == 224:
                $this->key_size = 28;
                break;
            case $length <= 128:
                $this->key_size = 16;
                break;
            case $length <= 192:
                $this->key_size = 24;
                break;
            default:
                $this->key_size = 32;
        }

        $this->explicit_key_length = true;
        $this->changed = true;
        $this->_setEngine();
    }

    /**
     * Sets the block length
     *
     * Valid block lengths are 128, 160, 192, 224, and 256.  If the length is less than 128, it will be rounded up to
     * 128.  If the length is greater than 128 and invalid, it will be rounded down to the closest valid amount.
     *
     * @access public
     * @param Integer $length
     */
    function setBlockLength($length)
    {
        $length >>= 5;
        if ($length > 8) {
            $length = 8;
        } elseif ($length < 4) {
            $length = 4;
        }
        $this->Nb = $length;
        $this->block_size = $length << 2;
        $this->changed = true;
        $this->_setEngine();
    }

    /**
     * Test for engine validity
     *
     * This is mainly just a wrapper to set things up for Crypt_Base::isValidEngine()
     *
     * @see Crypt_Base::Crypt_Base()
     * @param Integer $engine
     * @access public
     * @return Boolean
     */
    function isValidEngine($engine)
    {
        switch ($engine) {
            case CRYPT_ENGINE_OPENSSL:
                if ($this->block_size != 16) {
                    return false;
                }
                $this->cipher_name_openssl_ecb = 'aes-' . ($this->key_size << 3) . '-ecb';
                $this->cipher_name_openssl = 'aes-' . ($this->key_size << 3) . '-' . $this->_openssl_translate_mode();
                break;
            case CRYPT_ENGINE_MCRYPT:
                $this->cipher_name_mcrypt = 'rijndael-' . ($this->block_size << 3);
                if ($this->key_size % 8) { // is it a 160/224-bit key?
                    // mcrypt is not usable for them, only for 128/192/256-bit keys
                    return false;
                }
        }

        return parent::isValidEngine($engine);
    }

    /**
     * Setup the CRYPT_ENGINE_MCRYPT $engine
     *
     * @see Crypt_Base::_setupMcrypt()
     * @access private
     */
    function _setupMcrypt()
    {
        $this->key = str_pad(substr($this->key, 0, $this->key_size), $this->key_size, "\0");
        parent::_setupMcrypt();
    }

    /**
     * Encrypts a block
     *
     * @access private
     * @param String $in
     * @return String
     */
    function _encryptBlock($in)
    {
        static $tables;
        if (empty($tables)) {
            $tables = &$this->_getTables();
        }
        $t0   = $tables[0];
        $t1   = $tables[1];
        $t2   = $tables[2];
        $t3   = $tables[3];
        $sbox = $tables[4];

        $state = array();
        $words = unpack('N*', $in);

        $c = $this->c;
        $w = $this->w;
        $Nb = $this->Nb;
        $Nr = $this->Nr;

        // addRoundKey
        $wc = $Nb - 1;
        foreach ($words as $word) {
            $state[] = $word ^ $w[++$wc];
        }

        // fips-197.pdf#page=19, "Figure 5. Pseudo Code for the Cipher", states that this loop has four components -
        // subBytes, shiftRows, mixColumns, and addRoundKey. fips-197.pdf#page=30, "Implementation Suggestions Regarding
        // Various Platforms" suggests that performs enhanced implementations are described in Rijndael-ammended.pdf.
        // Rijndael-ammended.pdf#page=20, "Implementation aspects / 32-bit processor", discusses such an optimization.
        // Unfortunately, the description given there is not quite correct.  Per aes.spec.v316.pdf#page=19 [1],
        // equation (7.4.7) is supposed to use addition instead of subtraction, so we'll do that here, as well.

        // [1] http://fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.v316.pdf
        $temp = array();
        for ($round = 1; $round < $Nr; ++$round) {
            $i = 0; // $c[0] == 0
            $j = $c[1];
            $k = $c[2];
            $l = $c[3];

            while ($i < $Nb) {
                $temp[$i] = $t0[$state[$i] >> 24 & 0x000000FF] ^
                            $t1[$state[$j] >> 16 & 0x000000FF] ^
                            $t2[$state[$k] >>  8 & 0x000000FF] ^
                            $t3[$state[$l]       & 0x000000FF] ^
                            $w[++$wc];
                ++$i;
                $j = ($j + 1) % $Nb;
                $k = ($k + 1) % $Nb;
                $l = ($l + 1) % $Nb;
            }
            $state = $temp;
        }

        // subWord
        for ($i = 0; $i < $Nb; ++$i) {
            $state[$i] =   $sbox[$state[$i]       & 0x000000FF]        |
                          ($sbox[$state[$i] >>  8 & 0x000000FF] <<  8) |
                          ($sbox[$state[$i] >> 16 & 0x000000FF] << 16) |
                          ($sbox[$state[$i] >> 24 & 0x000000FF] << 24);
        }

        // shiftRows + addRoundKey
        $i = 0; // $c[0] == 0
        $j = $c[1];
        $k = $c[2];
        $l = $c[3];
        while ($i < $Nb) {
            $temp[$i] = ($state[$i] & 0xFF000000) ^
                        ($state[$j] & 0x00FF0000) ^
                        ($state[$k] & 0x0000FF00) ^
                        ($state[$l] & 0x000000FF) ^
                         $w[$i];
            ++$i;
            $j = ($j + 1) % $Nb;
            $k = ($k + 1) % $Nb;
            $l = ($l + 1) % $Nb;
        }

        switch ($Nb) {
            case 8:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5], $temp[6], $temp[7]);
            case 7:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5], $temp[6]);
            case 6:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5]);
            case 5:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4]);
            default:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3]);
        }
    }

    /**
     * Decrypts a block
     *
     * @access private
     * @param String $in
     * @return String
     */
    function _decryptBlock($in)
    {
        static $invtables;
        if (empty($invtables)) {
            $invtables = &$this->_getInvTables();
        }
        $dt0   = $invtables[0];
        $dt1   = $invtables[1];
        $dt2   = $invtables[2];
        $dt3   = $invtables[3];
        $isbox = $invtables[4];

        $state = array();
        $words = unpack('N*', $in);

        $c  = $this->c;
        $dw = $this->dw;
        $Nb = $this->Nb;
        $Nr = $this->Nr;

        // addRoundKey
        $wc = $Nb - 1;
        foreach ($words as $word) {
            $state[] = $word ^ $dw[++$wc];
        }

        $temp = array();
        for ($round = $Nr - 1; $round > 0; --$round) {
            $i = 0; // $c[0] == 0
            $j = $Nb - $c[1];
            $k = $Nb - $c[2];
            $l = $Nb - $c[3];

            while ($i < $Nb) {
                $temp[$i] = $dt0[$state[$i] >> 24 & 0x000000FF] ^
                            $dt1[$state[$j] >> 16 & 0x000000FF] ^
                            $dt2[$state[$k] >>  8 & 0x000000FF] ^
                            $dt3[$state[$l]       & 0x000000FF] ^
                            $dw[++$wc];
                ++$i;
                $j = ($j + 1) % $Nb;
                $k = ($k + 1) % $Nb;
                $l = ($l + 1) % $Nb;
            }
            $state = $temp;
        }

        // invShiftRows + invSubWord + addRoundKey
        $i = 0; // $c[0] == 0
        $j = $Nb - $c[1];
        $k = $Nb - $c[2];
        $l = $Nb - $c[3];

        while ($i < $Nb) {
            $word = ($state[$i] & 0xFF000000) |
                    ($state[$j] & 0x00FF0000) |
                    ($state[$k] & 0x0000FF00) |
                    ($state[$l] & 0x000000FF);

            $temp[$i] = $dw[$i] ^ ($isbox[$word       & 0x000000FF]        |
                                  ($isbox[$word >>  8 & 0x000000FF] <<  8) |
                                  ($isbox[$word >> 16 & 0x000000FF] << 16) |
                                  ($isbox[$word >> 24 & 0x000000FF] << 24));
            ++$i;
            $j = ($j + 1) % $Nb;
            $k = ($k + 1) % $Nb;
            $l = ($l + 1) % $Nb;
        }

        switch ($Nb) {
            case 8:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5], $temp[6], $temp[7]);
            case 7:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5], $temp[6]);
            case 6:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5]);
            case 5:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4]);
            default:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3]);
        }
    }

    /**
     * Setup the key (expansion)
     *
     * @see Crypt_Base::_setupKey()
     * @access private
     */
    function _setupKey()
    {
        // Each number in $rcon is equal to the previous number multiplied by two in Rijndael's finite field.
        // See http://en.wikipedia.org/wiki/Finite_field_arithmetic#Multiplicative_inverse
        static $rcon = array(0,
            0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000,
            0x20000000, 0x40000000, 0x80000000, 0x1B000000, 0x36000000,
            0x6C000000, 0xD8000000, 0xAB000000, 0x4D000000, 0x9A000000,
            0x2F000000, 0x5E000000, 0xBC000000, 0x63000000, 0xC6000000,
            0x97000000, 0x35000000, 0x6A000000, 0xD4000000, 0xB3000000,
            0x7D000000, 0xFA000000, 0xEF000000, 0xC5000000, 0x91000000
        );

        $this->key = str_pad(substr($this->key, 0, $this->key_size), $this->key_size, "\0");

        if (isset($this->kl['key']) && $this->key === $this->kl['key'] && $this->key_size === $this->kl['key_size'] && $this->block_size === $this->kl['block_size']) {
            // already expanded
            return;
        }
        $this->kl = array('key' => $this->key, 'key_size' => $this->key_size, 'block_size' => $this->block_size);

        $this->Nk = $this->key_size >> 2;
        // see Rijndael-ammended.pdf#page=44
        $this->Nr = max($this->Nk, $this->Nb) + 6;

        // shift offsets for Nb = 5, 7 are defined in Rijndael-ammended.pdf#page=44,
        //     "Table 8: Shift offsets in Shiftrow for the alternative block lengths"
        // shift offsets for Nb = 4, 6, 8 are defined in Rijndael-ammended.pdf#page=14,
        //     "Table 2: Shift offsets for different block lengths"
        switch ($this->Nb) {
            case 4:
            case 5:
            case 6:
                $this->c = array(0, 1, 2, 3);
                break;
            case 7:
                $this->c = array(0, 1, 2, 4);
                break;
            case 8:
                $this->c = array(0, 1, 3, 4);
        }

        $w = array_values(unpack('N*words', $this->key));

        $length = $this->Nb * ($this->Nr + 1);
        for ($i = $this->Nk; $i < $length; $i++) {
            $temp = $w[$i - 1];
            if ($i % $this->Nk == 0) {
                // according to <http://php.net/language.types.integer>, "the size of an integer is platform-dependent".
                // on a 32-bit machine, it's 32-bits, and on a 64-bit machine, it's 64-bits. on a 32-bit machine,
                // 0xFFFFFFFF << 8 == 0xFFFFFF00, but on a 64-bit machine, it equals 0xFFFFFFFF00. as such, doing 'and'
                // with 0xFFFFFFFF (or 0xFFFFFF00) on a 32-bit machine is unnecessary, but on a 64-bit machine, it is.
                $temp = (($temp << 8) & 0xFFFFFF00) | (($temp >> 24) & 0x000000FF); // rotWord
                $temp = $this->_subWord($temp) ^ $rcon[$i / $this->Nk];
            } elseif ($this->Nk > 6 && $i % $this->Nk == 4) {
                $temp = $this->_subWord($temp);
            }
            $w[$i] = $w[$i - $this->Nk] ^ $temp;
        }

        // convert the key schedule from a vector of $Nb * ($Nr + 1) length to a matrix with $Nr + 1 rows and $Nb columns
        // and generate the inverse key schedule.  more specifically,
        // according to <http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=23> (section 5.3.3),
        // "The key expansion for the Inverse Cipher is defined as follows:
        //        1. Apply the Key Expansion.
        //        2. Apply InvMixColumn to all Round Keys except the first and the last one."
        // also, see fips-197.pdf#page=27, "5.3.5 Equivalent Inverse Cipher"
        list($dt0, $dt1, $dt2, $dt3) = $this->_getInvTables();
        $temp = $this->w = $this->dw = array();
        for ($i = $row = $col = 0; $i < $length; $i++, $col++) {
            if ($col == $this->Nb) {
                if ($row == 0) {
                    $this->dw[0] = $this->w[0];
                } else {
                    // subWord + invMixColumn + invSubWord = invMixColumn
                    $j = 0;
                    while ($j < $this->Nb) {
                        $dw = $this->_subWord($this->w[$row][$j]);
                        $temp[$j] = $dt0[$dw >> 24 & 0x000000FF] ^
                                    $dt1[$dw >> 16 & 0x000000FF] ^
                                    $dt2[$dw >>  8 & 0x000000FF] ^
                                    $dt3[$dw       & 0x000000FF];
                        $j++;
                    }
                    $this->dw[$row] = $temp;
                }

                $col = 0;
                $row++;
            }
            $this->w[$row][$col] = $w[$i];
        }

        $this->dw[$row] = $this->w[$row];

        // Converting to 1-dim key arrays (both ascending)
        $this->dw = array_reverse($this->dw);
        $w  = array_pop($this->w);
        $dw = array_pop($this->dw);
        foreach ($this->w as $r => $wr) {
            foreach ($wr as $c => $wc) {
                $w[]  = $wc;
                $dw[] = $this->dw[$r][$c];
            }
        }
        $this->w  = $w;
        $this->dw = $dw;
    }

    /**
     * Performs S-Box substitutions
     *
     * @access private
     * @param Integer $word
     */
    function _subWord($word)
    {
        static $sbox;
        if (empty($sbox)) {
            list(,,,, $sbox) = $this->_getTables();
        }

        return  $sbox[$word       & 0x000000FF]        |
               ($sbox[$word >>  8 & 0x000000FF] <<  8) |
               ($sbox[$word >> 16 & 0x000000FF] << 16) |
               ($sbox[$word >> 24 & 0x000000FF] << 24);
    }

    /**
     * Provides the mixColumns and sboxes tables
     *
     * @see Crypt_Rijndael:_encryptBlock()
     * @see Crypt_Rijndael:_setupInlineCrypt()
     * @see Crypt_Rijndael:_subWord()
     * @access private
     * @return Array &$tables
     */
    function &_getTables()
    {
        static $tables;
        if (empty($tables)) {
            // according to <http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=19> (section 5.2.1),
            // precomputed tables can be used in the mixColumns phase. in that example, they're assigned t0...t3, so
            // those are the names we'll use.
            $t3 = array_map('intval', array(
                // with array_map('intval', ...) we ensure we have only int's and not
                // some slower floats converted by php automatically on high values
                0x6363A5C6, 0x7C7C84F8, 0x777799EE, 0x7B7B8DF6, 0xF2F20DFF, 0x6B6BBDD6, 0x6F6FB1DE, 0xC5C55491,
                0x30305060, 0x01010302, 0x6767A9CE, 0x2B2B7D56, 0xFEFE19E7, 0xD7D762B5, 0xABABE64D, 0x76769AEC,
                0xCACA458F, 0x82829D1F, 0xC9C94089, 0x7D7D87FA, 0xFAFA15EF, 0x5959EBB2, 0x4747C98E, 0xF0F00BFB,
                0xADADEC41, 0xD4D467B3, 0xA2A2FD5F, 0xAFAFEA45, 0x9C9CBF23, 0xA4A4F753, 0x727296E4, 0xC0C05B9B,
                0xB7B7C275, 0xFDFD1CE1, 0x9393AE3D, 0x26266A4C, 0x36365A6C, 0x3F3F417E, 0xF7F702F5, 0xCCCC4F83,
                0x34345C68, 0xA5A5F451, 0xE5E534D1, 0xF1F108F9, 0x717193E2, 0xD8D873AB, 0x31315362, 0x15153F2A,
                0x04040C08, 0xC7C75295, 0x23236546, 0xC3C35E9D, 0x18182830, 0x9696A137, 0x05050F0A, 0x9A9AB52F,
                0x0707090E, 0x12123624, 0x80809B1B, 0xE2E23DDF, 0xEBEB26CD, 0x2727694E, 0xB2B2CD7F, 0x75759FEA,
                0x09091B12, 0x83839E1D, 0x2C2C7458, 0x1A1A2E34, 0x1B1B2D36, 0x6E6EB2DC, 0x5A5AEEB4, 0xA0A0FB5B,
                0x5252F6A4, 0x3B3B4D76, 0xD6D661B7, 0xB3B3CE7D, 0x29297B52, 0xE3E33EDD, 0x2F2F715E, 0x84849713,
                0x5353F5A6, 0xD1D168B9, 0x00000000, 0xEDED2CC1, 0x20206040, 0xFCFC1FE3, 0xB1B1C879, 0x5B5BEDB6,
                0x6A6ABED4, 0xCBCB468D, 0xBEBED967, 0x39394B72, 0x4A4ADE94, 0x4C4CD498, 0x5858E8B0, 0xCFCF4A85,
                0xD0D06BBB, 0xEFEF2AC5, 0xAAAAE54F, 0xFBFB16ED, 0x4343C586, 0x4D4DD79A, 0x33335566, 0x85859411,
                0x4545CF8A, 0xF9F910E9, 0x02020604, 0x7F7F81FE, 0x5050F0A0, 0x3C3C4478, 0x9F9FBA25, 0xA8A8E34B,
                0x5151F3A2, 0xA3A3FE5D, 0x4040C080, 0x8F8F8A05, 0x9292AD3F, 0x9D9DBC21, 0x38384870, 0xF5F504F1,
                0xBCBCDF63, 0xB6B6C177, 0xDADA75AF, 0x21216342, 0x10103020, 0xFFFF1AE5, 0xF3F30EFD, 0xD2D26DBF,
                0xCDCD4C81, 0x0C0C1418, 0x13133526, 0xECEC2FC3, 0x5F5FE1BE, 0x9797A235, 0x4444CC88, 0x1717392E,
                0xC4C45793, 0xA7A7F255, 0x7E7E82FC, 0x3D3D477A, 0x6464ACC8, 0x5D5DE7BA, 0x19192B32, 0x737395E6,
                0x6060A0C0, 0x81819819, 0x4F4FD19E, 0xDCDC7FA3, 0x22226644, 0x2A2A7E54, 0x9090AB3B, 0x8888830B,
                0x4646CA8C, 0xEEEE29C7, 0xB8B8D36B, 0x14143C28, 0xDEDE79A7, 0x5E5EE2BC, 0x0B0B1D16, 0xDBDB76AD,
                0xE0E03BDB, 0x32325664, 0x3A3A4E74, 0x0A0A1E14, 0x4949DB92, 0x06060A0C, 0x24246C48, 0x5C5CE4B8,
                0xC2C25D9F, 0xD3D36EBD, 0xACACEF43, 0x6262A6C4, 0x9191A839, 0x9595A431, 0xE4E437D3, 0x79798BF2,
                0xE7E732D5, 0xC8C8438B, 0x3737596E, 0x6D6DB7DA, 0x8D8D8C01, 0xD5D564B1, 0x4E4ED29C, 0xA9A9E049,
                0x6C6CB4D8, 0x5656FAAC, 0xF4F407F3, 0xEAEA25CF, 0x6565AFCA, 0x7A7A8EF4, 0xAEAEE947, 0x08081810,
                0xBABAD56F, 0x787888F0, 0x25256F4A, 0x2E2E725C, 0x1C1C2438, 0xA6A6F157, 0xB4B4C773, 0xC6C65197,
                0xE8E823CB, 0xDDDD7CA1, 0x74749CE8, 0x1F1F213E, 0x4B4BDD96, 0xBDBDDC61, 0x8B8B860D, 0x8A8A850F,
                0x707090E0, 0x3E3E427C, 0xB5B5C471, 0x6666AACC, 0x4848D890, 0x03030506, 0xF6F601F7, 0x0E0E121C,
                0x6161A3C2, 0x35355F6A, 0x5757F9AE, 0xB9B9D069, 0x86869117, 0xC1C15899, 0x1D1D273A, 0x9E9EB927,
                0xE1E138D9, 0xF8F813EB, 0x9898B32B, 0x11113322, 0x6969BBD2, 0xD9D970A9, 0x8E8E8907, 0x9494A733,
                0x9B9BB62D, 0x1E1E223C, 0x87879215, 0xE9E920C9, 0xCECE4987, 0x5555FFAA, 0x28287850, 0xDFDF7AA5,
                0x8C8C8F03, 0xA1A1F859, 0x89898009, 0x0D0D171A, 0xBFBFDA65, 0xE6E631D7, 0x4242C684, 0x6868B8D0,
                0x4141C382, 0x9999B029, 0x2D2D775A, 0x0F0F111E, 0xB0B0CB7B, 0x5454FCA8, 0xBBBBD66D, 0x16163A2C
            ));

            foreach ($t3 as $t3i) {
                $t0[] = (($t3i << 24) & 0xFF000000) | (($t3i >>  8) & 0x00FFFFFF);
                $t1[] = (($t3i << 16) & 0xFFFF0000) | (($t3i >> 16) & 0x0000FFFF);
                $t2[] = (($t3i <<  8) & 0xFFFFFF00) | (($t3i >> 24) & 0x000000FF);
            }

            $tables = array(
                // The Precomputed mixColumns tables t0 - t3
                $t0,
                $t1,
                $t2,
                $t3,
                // The SubByte S-Box
                array(
                    0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
                    0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
                    0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
                    0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
                    0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
                    0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
                    0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
                    0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
                    0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
                    0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
                    0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
                    0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
                    0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
                    0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
                    0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
                    0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
                )
            );
        }
        return $tables;
    }

    /**
     * Provides the inverse mixColumns and inverse sboxes tables
     *
     * @see Crypt_Rijndael:_decryptBlock()
     * @see Crypt_Rijndael:_setupInlineCrypt()
     * @see Crypt_Rijndael:_setupKey()
     * @access private
     * @return Array &$tables
     */
    function &_getInvTables()
    {
        static $tables;
        if (empty($tables)) {
            $dt3 = array_map('intval', array(
                0xF4A75051, 0x4165537E, 0x17A4C31A, 0x275E963A, 0xAB6BCB3B, 0x9D45F11F, 0xFA58ABAC, 0xE303934B,
                0x30FA5520, 0x766DF6AD, 0xCC769188, 0x024C25F5, 0xE5D7FC4F, 0x2ACBD7C5, 0x35448026, 0x62A38FB5,
                0xB15A49DE, 0xBA1B6725, 0xEA0E9845, 0xFEC0E15D, 0x2F7502C3, 0x4CF01281, 0x4697A38D, 0xD3F9C66B,
                0x8F5FE703, 0x929C9515, 0x6D7AEBBF, 0x5259DA95, 0xBE832DD4, 0x7421D358, 0xE0692949, 0xC9C8448E,
                0xC2896A75, 0x8E7978F4, 0x583E6B99, 0xB971DD27, 0xE14FB6BE, 0x88AD17F0, 0x20AC66C9, 0xCE3AB47D,
                0xDF4A1863, 0x1A3182E5, 0x51336097, 0x537F4562, 0x6477E0B1, 0x6BAE84BB, 0x81A01CFE, 0x082B94F9,
                0x48685870, 0x45FD198F, 0xDE6C8794, 0x7BF8B752, 0x73D323AB, 0x4B02E272, 0x1F8F57E3, 0x55AB2A66,
                0xEB2807B2, 0xB5C2032F, 0xC57B9A86, 0x3708A5D3, 0x2887F230, 0xBFA5B223, 0x036ABA02, 0x16825CED,
                0xCF1C2B8A, 0x79B492A7, 0x07F2F0F3, 0x69E2A14E, 0xDAF4CD65, 0x05BED506, 0x34621FD1, 0xA6FE8AC4,
                0x2E539D34, 0xF355A0A2, 0x8AE13205, 0xF6EB75A4, 0x83EC390B, 0x60EFAA40, 0x719F065E, 0x6E1051BD,
                0x218AF93E, 0xDD063D96, 0x3E05AEDD, 0xE6BD464D, 0x548DB591, 0xC45D0571, 0x06D46F04, 0x5015FF60,
                0x98FB2419, 0xBDE997D6, 0x4043CC89, 0xD99E7767, 0xE842BDB0, 0x898B8807, 0x195B38E7, 0xC8EEDB79,
                0x7C0A47A1, 0x420FE97C, 0x841EC9F8, 0x00000000, 0x80868309, 0x2BED4832, 0x1170AC1E, 0x5A724E6C,
                0x0EFFFBFD, 0x8538560F, 0xAED51E3D, 0x2D392736, 0x0FD9640A, 0x5CA62168, 0x5B54D19B, 0x362E3A24,
                0x0A67B10C, 0x57E70F93, 0xEE96D2B4, 0x9B919E1B, 0xC0C54F80, 0xDC20A261, 0x774B695A, 0x121A161C,
                0x93BA0AE2, 0xA02AE5C0, 0x22E0433C, 0x1B171D12, 0x090D0B0E, 0x8BC7ADF2, 0xB6A8B92D, 0x1EA9C814,
                0xF1198557, 0x75074CAF, 0x99DDBBEE, 0x7F60FDA3, 0x01269FF7, 0x72F5BC5C, 0x663BC544, 0xFB7E345B,
                0x4329768B, 0x23C6DCCB, 0xEDFC68B6, 0xE4F163B8, 0x31DCCAD7, 0x63851042, 0x97224013, 0xC6112084,
                0x4A247D85, 0xBB3DF8D2, 0xF93211AE, 0x29A16DC7, 0x9E2F4B1D, 0xB230F3DC, 0x8652EC0D, 0xC1E3D077,
                0xB3166C2B, 0x70B999A9, 0x9448FA11, 0xE9642247, 0xFC8CC4A8, 0xF03F1AA0, 0x7D2CD856, 0x3390EF22,
                0x494EC787, 0x38D1C1D9, 0xCAA2FE8C, 0xD40B3698, 0xF581CFA6, 0x7ADE28A5, 0xB78E26DA, 0xADBFA43F,
                0x3A9DE42C, 0x78920D50, 0x5FCC9B6A, 0x7E466254, 0x8D13C2F6, 0xD8B8E890, 0x39F75E2E, 0xC3AFF582,
                0x5D80BE9F, 0xD0937C69, 0xD52DA96F, 0x2512B3CF, 0xAC993BC8, 0x187DA710, 0x9C636EE8, 0x3BBB7BDB,
                0x267809CD, 0x5918F46E, 0x9AB701EC, 0x4F9AA883, 0x956E65E6, 0xFFE67EAA, 0xBCCF0821, 0x15E8E6EF,
                0xE79BD9BA, 0x6F36CE4A, 0x9F09D4EA, 0xB07CD629, 0xA4B2AF31, 0x3F23312A, 0xA59430C6, 0xA266C035,
                0x4EBC3774, 0x82CAA6FC, 0x90D0B0E0, 0xA7D81533, 0x04984AF1, 0xECDAF741, 0xCD500E7F, 0x91F62F17,
                0x4DD68D76, 0xEFB04D43, 0xAA4D54CC, 0x9604DFE4, 0xD1B5E39E, 0x6A881B4C, 0x2C1FB8C1, 0x65517F46,
                0x5EEA049D, 0x8C355D01, 0x877473FA, 0x0B412EFB, 0x671D5AB3, 0xDBD25292, 0x105633E9, 0xD647136D,
                0xD7618C9A, 0xA10C7A37, 0xF8148E59, 0x133C89EB, 0xA927EECE, 0x61C935B7, 0x1CE5EDE1, 0x47B13C7A,
                0xD2DF599C, 0xF2733F55, 0x14CE7918, 0xC737BF73, 0xF7CDEA53, 0xFDAA5B5F, 0x3D6F14DF, 0x44DB8678,
                0xAFF381CA, 0x68C43EB9, 0x24342C38, 0xA3405FC2, 0x1DC37216, 0xE2250CBC, 0x3C498B28, 0x0D9541FF,
                0xA8017139, 0x0CB3DE08, 0xB4E49CD8, 0x56C19064, 0xCB84617B, 0x32B670D5, 0x6C5C7448, 0xB85742D0
            ));

            foreach ($dt3 as $dt3i) {
                $dt0[] = (($dt3i << 24) & 0xFF000000) | (($dt3i >>  8) & 0x00FFFFFF);
                $dt1[] = (($dt3i << 16) & 0xFFFF0000) | (($dt3i >> 16) & 0x0000FFFF);
                $dt2[] = (($dt3i <<  8) & 0xFFFFFF00) | (($dt3i >> 24) & 0x000000FF);
            };

            $tables = array(
                // The Precomputed inverse mixColumns tables dt0 - dt3
                $dt0,
                $dt1,
                $dt2,
                $dt3,
                // The inverse SubByte S-Box
                array(
                    0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
                    0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
                    0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
                    0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
                    0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
                    0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
                    0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
                    0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
                    0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
                    0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
                    0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
                    0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
                    0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
                    0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
                    0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
                    0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
                )
            );
        }
        return $tables;
    }

    /**
     * Setup the performance-optimized function for de/encrypt()
     *
     * @see Crypt_Base::_setupInlineCrypt()
     * @access private
     */
    function _setupInlineCrypt()
    {
        // Note: _setupInlineCrypt() will be called only if $this->changed === true
        // So here we are'nt under the same heavy timing-stress as we are in _de/encryptBlock() or de/encrypt().
        // However...the here generated function- $code, stored as php callback in $this->inline_crypt, must work as fast as even possible.

        $lambda_functions =& Crypt_Rijndael::_getLambdaFunctions();

        // We create max. 10 hi-optimized code for memory reason. Means: For each $key one ultra fast inline-crypt function.
        // (Currently, for Crypt_Rijndael/AES, one generated $lambda_function cost on php5.5@32bit ~80kb unfreeable mem and ~130kb on php5.5@64bit)
        // After that, we'll still create very fast optimized code but not the hi-ultimative code, for each $mode one.
        $gen_hi_opt_code = (bool)( count($lambda_functions) < 10 );

        // Generation of a uniqe hash for our generated code
        $code_hash = "Crypt_Rijndael, {$this->mode}, {$this->Nr}, {$this->Nb}";
        if ($gen_hi_opt_code) {
            $code_hash = str_pad($code_hash, 32) . $this->_hashInlineCryptFunction($this->key);
        }

        if (!isset($lambda_functions[$code_hash])) {
            switch (true) {
                case $gen_hi_opt_code:
                    // The hi-optimized $lambda_functions will use the key-words hardcoded for better performance.
                    $w  = $this->w;
                    $dw = $this->dw;
                    $init_encrypt = '';
                    $init_decrypt = '';
                    break;
                default:
                    for ($i = 0, $cw = count($this->w); $i < $cw; ++$i) {
                        $w[]  = '$w['  . $i . ']';
                        $dw[] = '$dw[' . $i . ']';
                    }
                    $init_encrypt = '$w  = $self->w;';
                    $init_decrypt = '$dw = $self->dw;';
            }

            $Nr = $this->Nr;
            $Nb = $this->Nb;
            $c  = $this->c;

            // Generating encrypt code:
            $init_encrypt.= '
                static $tables;
                if (empty($tables)) {
                    $tables = &$self->_getTables();
                }
                $t0   = $tables[0];
                $t1   = $tables[1];
                $t2   = $tables[2];
                $t3   = $tables[3];
                $sbox = $tables[4];
            ';

            $s  = 'e';
            $e  = 's';
            $wc = $Nb - 1;

            // Preround: addRoundKey
            $encrypt_block = '$in = unpack("N*", $in);'."\n";
            for ($i = 0; $i < $Nb; ++$i) {
                $encrypt_block .= '$s'.$i.' = $in['.($i + 1).'] ^ '.$w[++$wc].";\n";
            }

            // Mainrounds: shiftRows + subWord + mixColumns + addRoundKey
            for ($round = 1; $round < $Nr; ++$round) {
                list($s, $e) = array($e, $s);
                for ($i = 0; $i < $Nb; ++$i) {
                    $encrypt_block.=
                        '$'.$e.$i.' =
                        $t0[($'.$s.$i                  .' >> 24) & 0xff] ^
                        $t1[($'.$s.(($i + $c[1]) % $Nb).' >> 16) & 0xff] ^
                        $t2[($'.$s.(($i + $c[2]) % $Nb).' >>  8) & 0xff] ^
                        $t3[ $'.$s.(($i + $c[3]) % $Nb).'        & 0xff] ^
                        '.$w[++$wc].";\n";
                }
            }

            // Finalround: subWord + shiftRows + addRoundKey
            for ($i = 0; $i < $Nb; ++$i) {
                $encrypt_block.=
                    '$'.$e.$i.' =
                     $sbox[ $'.$e.$i.'        & 0xff]        |
                    ($sbox[($'.$e.$i.' >>  8) & 0xff] <<  8) |
                    ($sbox[($'.$e.$i.' >> 16) & 0xff] << 16) |
                    ($sbox[($'.$e.$i.' >> 24) & 0xff] << 24);'."\n";
            }
            $encrypt_block .= '$in = pack("N*"'."\n";
            for ($i = 0; $i < $Nb; ++$i) {
                $encrypt_block.= ',
                    ($'.$e.$i                  .' & '.((int)0xFF000000).') ^
                    ($'.$e.(($i + $c[1]) % $Nb).' &         0x00FF0000   ) ^
                    ($'.$e.(($i + $c[2]) % $Nb).' &         0x0000FF00   ) ^
                    ($'.$e.(($i + $c[3]) % $Nb).' &         0x000000FF   ) ^
                    '.$w[$i]."\n";
            }
            $encrypt_block .= ');';

            // Generating decrypt code:
            $init_decrypt.= '
                static $invtables;
                if (empty($invtables)) {
                    $invtables = &$self->_getInvTables();
                }
                $dt0   = $invtables[0];
                $dt1   = $invtables[1];
                $dt2   = $invtables[2];
                $dt3   = $invtables[3];
                $isbox = $invtables[4];
            ';

            $s  = 'e';
            $e  = 's';
            $wc = $Nb - 1;

            // Preround: addRoundKey
            $decrypt_block = '$in = unpack("N*", $in);'."\n";
            for ($i = 0; $i < $Nb; ++$i) {
                $decrypt_block .= '$s'.$i.' = $in['.($i + 1).'] ^ '.$dw[++$wc].';'."\n";
            }

            // Mainrounds: shiftRows + subWord + mixColumns + addRoundKey
            for ($round = 1; $round < $Nr; ++$round) {
                list($s, $e) = array($e, $s);
                for ($i = 0; $i < $Nb; ++$i) {
                    $decrypt_block.=
                        '$'.$e.$i.' =
                        $dt0[($'.$s.$i                        .' >> 24) & 0xff] ^
                        $dt1[($'.$s.(($Nb + $i - $c[1]) % $Nb).' >> 16) & 0xff] ^
                        $dt2[($'.$s.(($Nb + $i - $c[2]) % $Nb).' >>  8) & 0xff] ^
                        $dt3[ $'.$s.(($Nb + $i - $c[3]) % $Nb).'        & 0xff] ^
                        '.$dw[++$wc].";\n";
                }
            }

            // Finalround: subWord + shiftRows + addRoundKey
            for ($i = 0; $i < $Nb; ++$i) {
                $decrypt_block.=
                    '$'.$e.$i.' =
                     $isbox[ $'.$e.$i.'        & 0xff]        |
                    ($isbox[($'.$e.$i.' >>  8) & 0xff] <<  8) |
                    ($isbox[($'.$e.$i.' >> 16) & 0xff] << 16) |
                    ($isbox[($'.$e.$i.' >> 24) & 0xff] << 24);'."\n";
            }
            $decrypt_block .= '$in = pack("N*"'."\n";
            for ($i = 0; $i < $Nb; ++$i) {
                $decrypt_block.= ',
                    ($'.$e.$i.                        ' & '.((int)0xFF000000).') ^
                    ($'.$e.(($Nb + $i - $c[1]) % $Nb).' &         0x00FF0000   ) ^
                    ($'.$e.(($Nb + $i - $c[2]) % $Nb).' &         0x0000FF00   ) ^
                    ($'.$e.(($Nb + $i - $c[3]) % $Nb).' &         0x000000FF   ) ^
                    '.$dw[$i]."\n";
            }
            $decrypt_block .= ');';

            $lambda_functions[$code_hash] = $this->_createInlineCryptFunction(
                array(
                   'init_crypt'    => '',
                   'init_encrypt'  => $init_encrypt,
                   'init_decrypt'  => $init_decrypt,
                   'encrypt_block' => $encrypt_block,
                   'decrypt_block' => $decrypt_block
                )
            );
        }
        $this->inline_crypt = $lambda_functions[$code_hash];
    }
}