<?php 

$transactionId = $_GET['transactionId'];
$userOrderId = $_GET['userOrderId'];
$amount = $_GET['amount'];
$currency = $_GET['currency'];
$status = $_GET['status'];
$orderCreatedAt = $_GET['orderCreatedAt'];
$orderCompleteAt = $_GET['orderCompleteAt'];
$refundedAmount = $_GET['refundedAmount'];
$hash = $_GET['hash']; // generated at payment process >> must be equal with $hash2use
$ApiSecret = "Ijh^5*VZut*XYKoPaLcP7Xn9IpO9fv9yOqtUm8+R_-yK4Wjfs6~zec%xBH@r*0ZK";

$hash2encode = $transactionId . $userOrderId . $amount . $ApiSecret;
$hash2use = hash('sha256', $hash2encode);

if($hash2use == $hash) {
	//VALID >> Add amount to user account
}else {
	//ERROR >> Add payment to payment with errors
}

?>