<?php
$post = $_POST;
$merchant_key = '------';
$merchant_salt = '-----';
$hash = base64_encode( hash_hmac('sha256', $post['merchant_oid'].$merchant_salt.$post['status'].$post['total_amount'], $merchant_key, true) );
$dr = $post['status'];
if($dr == 'success'){
echo "OK";
}
?>kendi key ve saltınızı güncelleyip deneyin.