mask

<?php
$override = '******';
$override_length = strlen($override);
$override_middle = intdiv($override_length, 2);
$url = $website;
$url_length = strlen($url);
$middle = intdiv($url_length, 2);
$start_position = max(0, $middle - $override_middle);
$end_position = min($url_length, $middle - $override_length - $override_middle);
$new_url = substr_replace($url, $override, $start_position, $end_position);
echo $new_url;
?>