decrypting a string cripted in php

hello all!
I have an external site developed in php that send me a string cripted with this php function:
const SALT = "chiave";
     public static function myEncrypt($text)
    {
        return rawurlencode(base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, self::SALT, $text, MCRYPT_MODE_ECB, mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB), MCRYPT_RAND))));
    }


and then I need to decrypt this in asp.net.
How can I do?
please...
the php function for decrypting is:
    public static function myDecrypt($text)
    {
        return mcrypt_decrypt(MCRYPT_RIJNDAEL_256, self::SALT, base64_decode(rawurldecode($text)), MCRYPT_MODE_ECB, mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB), MCRYPT_RAND));< ...