[eluser]Unknown[/eluser]
i have answer.
$name = $_FILES['userfile']['name']; // get file name from form
$fileNameParts = explode( ".", $name ); // explode file name to two part
$fileExtension = end( $fileNameParts ); // give extension
$fileExtension = strtolower( $fileExtension ); // convert to lower case
$encripted_pic_name = md5($name).".".$fileExtension; // new file name
$config['file_name'] = $encripted_pic_name; //set file name
thanks..

mashuri.web.id