protected function genNonce() {
		$chars = '1234567890abcdefghijklmnopqrstuvwxyz';
		$rnd_string = '';
		$num_chars = strlen($chars);
		$size = mt_rand(41, 59);
		for($i=0; $i<$size; $i++) {
			$rnd_string .= $chars[mt_rand(0, $num_chars - 1)];
		}
		return $rnd_string;
	}