微信开发之密文模式 mcrypt_module_open 走不过

$ciphertext_dec = base64_decode($encrypted);

            $module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, ‘‘, MCRYPT_MODE_CBC, ‘‘);

            $iv = substr($this->key, 0, 16);

            mcrypt_generic_init($module, $this->key, $iv);



//解密

            $decrypted = mdecrypt_generic($module, $ciphertext_dec);

            mcrypt_generic_deinit($module);

            mcrypt_module_close($module);