failure.php

<?php
$status=$_POST["status"];
$firstname=$_POST["firstname"];
$amount=$_POST["amount"];
$txnid=$_POST["txnid"];

$posted_hash=$_POST["hash"];
$key=$_POST["key"];
$productinfo=$_POST["productinfo"];
$email=$_POST["email"];
$salt="UkojH5TS";

// Salt should be same Post Request 

If (isset($_POST["additionalCharges"])) {
       $additionalCharges=$_POST["additionalCharges"];
        $retHashSeq = $additionalCharges.'|'.$salt.'|'.$status.'|||||||||||'.$email.'|'.$firstname.'|'.$productinfo.'|'.$amount.'|'.$txnid.'|'.$key;
  } else {
        $retHashSeq = $salt.'|'.$status.'|||||||||||'.$email.'|'.$firstname.'|'.$productinfo.'|'.$amount.'|'.$txnid.'|'.$key;
         }
		 $hash = hash("sha512", $retHashSeq);
  
       if ($hash != $posted_hash) {
	       echo "Invalid Transaction. Please try again";
		   } else {
         echo "<h3>Your order status is ". $status .".</h3>";
         echo "<h4>Your transaction id for this transaction is ".$txnid.". You may try making the payment by clicking the link below.</h4>";
		 } 
?>