- hash_hmac: documentation ( source)
<?php
$qs = 'city=York&zip=29745&amount=208.82&customfield1=41047948&exp=0419&action=sale&customfield2=FTML&state=SC&returnurl=http%253A%252F%252Fwwwdev.comporium.com%253A8181%252FuserAccount.asmx%252FtrustCommerceReturnURL&cc=1111&name=Domingo+Hilario&token=MzNlOGIyYzJjMTQ5NDZhZjc2NzcxNGFlODdmOGU3MDU%253D&address1=722+Erinbrook+CT&cvv=';
echo hash_hmac('sha1',$qs, 'c0mpTest19');
?>