$challenge = defaults($_GET, 'challenge' , '');
$sec = defaults($_GET, 'sec' , '');
$dfrn_version = (float) defaults($_GET, 'dfrn_version' , 2.0);
$challenge = defaults($_GET, 'challenge' , '');
$sec = defaults($_GET, 'sec' , '');
$dfrn_version = (float) defaults($_GET, 'dfrn_version' , 2.0);