AES.php

<?php

/**
 * Pure-PHP implementation of AES.
 *
 * Uses mcrypt, if available/possible, and an internal implementation, otherwise.
 *
 * PHP versions 4 and 5
 *
 * NOTE: Since AES.php is (for compatibility and phpseclib-historical reasons) virtually
 * just a wrapper to Rijndael.php you may consider using Rijndael.php instead of
 * to save one include_once().
 *
 * If {@link self::setKeyLength() setKeyLength()} isn't called, it'll be calculated from
 * {@link self::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 self::setKey() setKey()}
 * is called, again, at which point, it'll be recalculated.
 *
 * Since Crypt_AES extends Crypt_Rijndael, some functions are available to be called that, in the context of AES, don't
 * make a whole lot of sense.  {@link self::setBlockLength() setBlockLength()}, for instance.  Calling that function,
 * however possible, won't do anything (AES has a fixed block length whereas Rijndael has a variable one).
 *
 * Here's a short example of how to use this library:
 * <code>
 * <?php
 *    include 'Crypt/AES.php';
 *
 *    $aes = new Crypt_AES();
 *
 *    $aes->setKey('abcdefghijklmnop');
 *
 *    $size = 10 * 1024;
 *    $plaintext = '';
 *    for ($i = 0; $i < $size; $i++) {
 *        $plaintext.= 'a';
 *    }
 *
 *    echo $aes->decrypt($aes->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_AES
 * @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_Rijndael
 */
if (!class_exists('Crypt_Rijndael')) {
    include_once 'Rijndael.php';
}

/**#@+
 * @access public
 * @see self::encrypt()
 * @see self::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_AES_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_AES_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_AES_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_AES_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_AES_MODE_OFB', CRYPT_MODE_OFB);
/**#@-*/

/**
 * Pure-PHP implementation of AES.
 *
 * @package Crypt_AES
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class Crypt_AES extends Crypt_Rijndael
{
    /**
     * The namespace used by the cipher for its constants.
     *
     * @see Crypt_Base::const_namespace
     * @var string
     * @access private
     */
    var $const_namespace = 'AES';

    /**
     * Dummy function
     *
     * Since Crypt_AES extends Crypt_Rijndael, this function is, technically, available, but it doesn't do anything.
     *
     * @see Crypt_Rijndael::setBlockLength()
     * @access public
     * @param int $length
     */
    function setBlockLength($length)
    {
        return;
    }

    /**
     * Sets the key length
     *
     * Valid key lengths are 128, 192, 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.
     *
     * @see Crypt_Rijndael:setKeyLength()
     * @access public
     * @param int $length
     */
    function setKeyLength($length)
    {
        switch ($length) {
            case 160:
                $length = 192;
                break;
            case 224:
                $length = 256;
        }
        parent::setKeyLength($length);
    }

    /**
     * Sets the key.
     *
     * Rijndael supports five different key lengths, AES only supports three.
     *
     * @see Crypt_Rijndael:setKey()
     * @see setKeyLength()
     * @access public
     * @param string $key
     */
    function setKey($key)
    {
        parent::setKey($key);

        if (!$this->explicit_key_length) {
            $length = strlen($key);
            switch (true) {
                case $length <= 16:
                    $this->key_length = 16;
                    break;
                case $length <= 24:
                    $this->key_length = 24;
                    break;
                default:
                    $this->key_length = 32;
            }
            $this->_setEngine();
        }
    }
}