this is how simple of code that could be used to put in place
<?php
$client_seed = '769325dfae4b68c5ad8f97b1690e5a1d';
$server_seed = 'e6a69fe81fded079b1d9cfc479db40f1410c72ea12754d12dc1dad4461dfb608';
$result_seed = hash_hmac('sha512', $server_seed, $client_seed);
$result_number = hexdec(substr($result_seed,0,10));
$rolled_number = abs($result_number % 100);
echo $rolled_number;
?>then if they want to check it they can go to
http://phptester.net/