<?php

/**

 * Zend Framework

 *

 * LICENSE

 *

 * This source file is subject to the new BSD license that is bundled

 * with this package in the file LICENSE.txt.

 * It is also available through the world-wide-web at this URL:

 * http://framework.zend.com/license/new-bsd

 * If you did not receive a copy of the license and are unable to

 * obtain it through the world-wide-web, please send an email

 * to license@zend.com so we can send you a copy immediately.

 *

 * @category   Zend

 * @package    Zend_InfoCard

 * @subpackage Zend_InfoCard_Cipher

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 * @version    $Id: Aes256cbc.php 20096 2010-01-06 02:05:09Z bkarwin $

 */

/**

 * Zend_InfoCard_Cipher_Symmetric_Adapter_Abstract

 */

require_once 'Zend/InfoCard/Cipher/Symmetric/Adapter/Abstract.php';

/**

 * Zend_InfoCard_Cipher_Symmetric_Aes256cbc_Interface

 */

require_once 'Zend/InfoCard/Cipher/Symmetric/Aes256cbc/Interface.php';

/**

 * Implements AES256 with CBC encryption implemented using the mCrypt extension

 *

 * @category   Zend

 * @package    Zend_InfoCard

 * @subpackage Zend_InfoCard_Cipher

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_InfoCard_Cipher_Symmetric_Adapter_Aes256cbc

    extends Zend_InfoCard_Cipher_Symmetric_Adapter_Abstract

    implements Zend_InfoCard_Cipher_Symmetric_Aes256cbc_Interface

{

    /**

     * The MCRYPT Cipher constant for this encryption

     */

    const MCRYPT_CIPHER = MCRYPT_RIJNDAEL_128;

    /**

     * The MCRYPT Mode constant for this encryption

     */

    const MCRYPT_MODE   = MCRYPT_MODE_CBC;

    /**

     * The default length of the IV to use

     */

    const IV_LENGTH     = 16;

    /**

     * The object constructor

     *

     * @throws Zend_InfoCard_Cipher_Exception

     */

    public function __construct()

    {

        // Can't test for this

        // @codeCoverageIgnoreStart

        if(!extension_loaded('mcrypt')) {

            require_once 'Zend/InfoCard/Cipher/Exception.php';

            throw new Zend_InfoCard_Cipher_Exception("Use of the AES256CBC Cipher requires the mcrypt extension");

        }

        // @codeCoveregIgnoreEnd

    }

    /**

     * Decrypts data using the AES Algorithm using the mCrypt extension

     *

     * @throws Zend_InfoCard_Cipher_Exception

     * @param string $encryptedData The encrypted data in binary format

     * @param string $decryptionKey The decryption key

     * @param integer $iv_length The IV length to use

     * @return string the decrypted data with any terminating nulls removed

     */

    public function decrypt($encryptedData, $decryptionKey, $iv_length = null)

    {

        $iv_length = ($iv_length === null) ? self::IV_LENGTH : $iv_length;

        $mcrypt_iv = null;

        if($iv_length > 0) {

             $mcrypt_iv = substr($encryptedData, 0, $iv_length);

            $encryptedData = substr($encryptedData, $iv_length);

        }

        $decrypted = mcrypt_decrypt(self::MCRYPT_CIPHER, $decryptionKey, $encryptedData, self::MCRYPT_MODE, $mcrypt_iv);

        if(!$decrypted) {

            require_once 'Zend/InfoCard/Cipher/Exception.php';

            throw new Zend_InfoCard_Cipher_Exception("Failed to decrypt data using AES256CBC Algorithm");

        }

        $decryptedLength = strlen($decrypted);

        $paddingLength = substr($decrypted, $decryptedLength -1, 1);

        $decrypted = substr($decrypted, 0, $decryptedLength - ord($paddingLength));

        return rtrim($decrypted, "\0");

    }

}