<?php

/**

 * Crypt_RSA allows to do following operations:

 *     - key pair generation

 *     - encryption and decryption

 *     - signing and sign validation

 *

 * PHP versions 4 and 5

 *

 * LICENSE: This source file is subject to version 3.0 of the PHP license

 * that is available through the world-wide-web at the following URI:

 * http://www.php.net/license/3_0.txt.  If you did not receive a copy of

 * the PHP License and are unable to obtain it through the web, please

 * send a note to license@php.net so we can mail you a copy immediately.

 *

 * @category   Encryption

 * @package    Crypt_RSA

 * @author     Alexander Valyalkin <valyala@gmail.com>

 * @copyright  2005, 2006 Alexander Valyalkin

 * @license    http://www.php.net/license/3_0.txt  PHP License 3.0

 * @version    1.2.0b

 * @link       http://pear.php.net/package/Crypt_RSA

 */



/**

 * RSA error handling facilities

 */

require_once 'ErrorHandler.php';



/**

 * Crypt_RSA_MathLoader class.

 *

 * Provides static function:

 *  - loadWrapper($wrapper_name) - loads RSA math wrapper with name $wrapper_name

 *                                 or most suitable wrapper if $wrapper_name == 'default'

 *

 * Example usage:

 *    // load BigInt wrapper

 *    $big_int_wrapper = &Crypt_RSA_MathLoader::loadWrapper('BigInt');

 * 

 *    // load BCMath wrapper

 *    $bcmath_wrapper = &Crypt_RSA_MathLoader::loadWrapper('BCMath');

 * 

 *    // load the most suitable wrapper

 *    $bcmath_wrapper = &Crypt_RSA_MathLoader::loadWrapper();

 * 

 * @category   Encryption

 * @package    Crypt_RSA

 * @author     Alexander Valyalkin <valyala@gmail.com>

 * @copyright  2005, 2006 Alexander Valyalkin

 * @license    http://www.php.net/license/3_0.txt  PHP License 3.0

 * @link       http://pear.php.net/package/Crypt_RSA

 * @version    @package_version@

 * @access     public

 */

class Crypt_RSA_MathLoader

{

    /**

     * Loads RSA math wrapper with name $wrapper_name.

     * Implemented wrappers can be found at Crypt/RSA/Math folder.

     * Read docs/Crypt_RSA/docs/math_wrappers.txt for details

     *

     * This is a static function:

     *    // load BigInt wrapper

     *    $big_int_wrapper = &Crypt_RSA_MathLoader::loadWrapper('BigInt');

     *

     *    // load BCMath wrapper

     *    $bcmath_wrapper = &Crypt_RSA_MathLoader::loadWrapper('BCMath');

     *

     * @param string  $wrapper_name

     * @return object

     *         Reference to object of wrapper with name $wrapper_name on success

     *         or PEAR_Error object on error

     *

     * @access public

     */

    function &loadWrapper($wrapper_name = 'default')

    {

        static $math_objects = array();

        // ordered by performance. GMP is the fastest math library, BCMath - the slowest.

        static $math_wrappers = array('GMP', 'BigInt', 'BCMath',);



        if (isset($math_objects[$wrapper_name])) {

            /*

                wrapper with name $wrapper_name is already loaded and created.

                Return reference to existing copy of wrapper

            */

            return $math_objects[$wrapper_name];

        }



        $err_handler = &new Crypt_RSA_ErrorHandler;



        if ($wrapper_name === 'default') {

            // try to load the most suitable wrapper

            $n = sizeof($math_wrappers);

            for ($i = 0; $i < $n; $i++) {

                $obj = &Crypt_RSA_MathLoader::loadWrapper($math_wrappers[$i]);

                if (!$err_handler->isError($obj)) {

                    // wrapper for $math_wrappers[$i] successfully loaded

                    // register it as default wrapper and return reference to it

                    return $math_objects['default'] = &$obj;

                }

            }

            // can't load any wrapper

            $err_handler->pushError("can't load any wrapper for existing math libraries", CRYPT_RSA_ERROR_NO_WRAPPERS);

            return $err_handler->getLastError();

        }



        $class_name = 'Crypt_RSA_Math_' . $wrapper_name;

        $class_filename = dirname(__FILE__) . '/Math/' . $wrapper_name . '.php';



        if (!is_file($class_filename)) {

            $err_handler->pushError("can't find file [{$class_filename}] for RSA math wrapper [{$wrapper_name}]", CRYPT_RSA_ERROR_NO_FILE);

            return $err_handler->getLastError();

        }

        require_once($class_filename);

        if (!class_exists($class_name)) {

            $err_handler->pushError("can't find class [{$class_name}] in file [{$class_filename}]", CRYPT_RSA_ERROR_NO_CLASS);

            return $err_handler->getLastError();

        }



        // create and return wrapper object on success or PEAR_Error object on error

        $obj = &new $class_name;

        if ($obj->errstr) {

            // cannot load required extension for math wrapper

            $err_handler->pushError($obj->errstr, CRYPT_RSA_ERROR_NO_EXT);

            return $err_handler->getLastError();

        }

        return $math_objects[$wrapper_name] = &$obj;

    }

}



?>