public function initContent()
 {
     parent::initContent();
     $cart = $this->context->cart;
     $obj = new Paytm();
     $obj->execPayment($cart);
     $this->context->smarty->assign(array('nbProducts' => $cart->nbProducts(), 'cust_currency' => $cart->id_currency, 'total' => $cart->getOrderTotal(true, Cart::BOTH), 'isoCode' => $this->context->language->iso_code, 'this_path' => $this->module->getPathUri(), 'this_path_ssl' => Tools::getShopDomainSsl(true, true) . __PS_BASE_URI__ . 'modules/' . $this->module->name . '/'));
     $this->setTemplate('payment_execution.tpl');
 }
<?php

include dirname(__FILE__) . '/../../config/config.inc.php';
include dirname(__FILE__) . '/../../header.php';
include dirname(__FILE__) . '/paytm.php';
$paytm = new Paytm();
if (isset($_POST) && isset($_POST['CHECKSUMHASH'])) {
    $paytm->processPayment();
}
include_once dirname(__FILE__) . '/../../footer.php';
?>
 
 public function postProcess()
 {
     $order_id = $_POST['ORDERID'];
     $res_code = $_POST['RESPCODE'];
     $res_desc = $_POST['RESPMSG'];
     $checksum_recv = $_POST['CHECKSUMHASH'];
     $paramList = $_POST;
     //var_dump($paramList);
     $secret_key = Configuration::get('PayTM_SECRET_KEY');
     $order_amount = $_POST['TXNAMOUNT'];
     $bool = "FALSE";
     $bool = verifychecksum_e($paramList, $secret_key, $checksum_recv);
     /*if(isset($DR)){
     			$DR = preg_replace("/\s/","+",$DR);
     			$rc4 = new Crypt_RC4($secret_key);
     			$QueryString = base64_decode($DR);
     			$rc4->decrypt($QueryString);
     			$QueryString = explode('&',$QueryString);
     			$response = array();
     			foreach($QueryString as $param){
     				$param = explode('=',$param);
     				$response[$param[0]] = urldecode($param[1]);
     				array(8) { ["RESPCODE"]=> string(3) "141" ["RESPMSG"]=> string(26) "Cancel Request by Customer" ["STATUS"]=> string(11) "TXN_FAILURE" ["MID"]=> string(20) "pebble49164290093828" ["TXNAMOUNT"]=> string(3) "199" ["ORDERID"]=> string(4) "1105" ["TXNID"]=> string(4) "9051" ["CHECKSUMHASH"]=> string(108) "8JTqSis+Uqe2iVMo/vWLgjFQkay2pZQkoN/uUVaBbkZrwkYEZMXIKfKy9NfYd2Fk9JaHiemzwNVpfRJrqiWzyeDWxZSJBhCi5NBEaTdbcZA=" } 
     			}
     		}*/
     $cartID = $order_id;
     $extras = array();
     $extras['transaction_id'] = $_POST['TXNID'];
     $cart = new Cart(intval($cartID));
     $amount = $cart->getOrderTotal(true, Cart::BOTH);
     $responseMsg = $_POST['RESPMSG'];
     if ($bool == "TRUE") {
         if ($res_code == "01") {
             $status_code = "Ok";
             $message = "Transaction Successful";
             // $status = "15" ;
             $status = Configuration::get('Paytm_ID_ORDER_SUCCESS');
         } else {
             if ($res_code == "141") {
                 $responseMsg = "Transaction Cancelled. ";
                 $message = "Transaction Cancelled";
                 $status = "6";
             } else {
                 $responseMsg = "Transaction Failed. ";
                 $message = "Transaction Failed";
                 $status = Configuration::get('Paytm_ID_ORDER_FAILED');
             }
         }
     } else {
         $status_code = "Failed";
         $responseMsg = "Security Error ..!";
         $status = Configuration::get('Paytm_ID_ORDER_FAILED');
     }
     $history_message = $responseMsg . '. Paytm Payment ID: ' . $_POST['TXNID'];
     $obj = new Paytm();
     $obj->validateOrder(intval($cart->id), $status, $order_amount, $obj->displayName, $history_message, $extras, '', false, $cart->secure_key);
     $this->context->smarty->assign(array('status' => $status_code, 'responseMsg' => $message, 'this_path' => $this->module->getPathUri(), 'this_path_ssl' => Tools::getShopDomainSsl(true, true) . __PS_BASE_URI__ . 'modules/' . $this->module->name . '/'));
     $cart_qties == 0;
     $cart->delete();
     $this->setTemplate('payment_response.tpl');
 }