- gmdate: documentation ( source)
- md5: documentation ( source)
<?php
$apikey = '2w6a9c39hb7hnxvsvnb9rzgr';
$secret = 'KaEvDVeF86HjAEV4ppZk5Xaa';
$timestamp = gmdate('U', 1200603038); //
$sig = md5($apikey . $secret . $timestamp);
echo "$sig\n";