$paytmConfig['MID'], "ORDER_ID" => $orderId, "CUST_ID" => $customerId, "TXN_AMOUNT" => $txnAmount, "CHANNEL_ID" => $paytmConfig['CHANNEL_ID'], "INDUSTRY_TYPE_ID" => $paytmConfig['INDUSTRY_TYPE'], "WEBSITE" => $paytmConfig['WEBSITE'], "CALLBACK_URL" => $paytmConfig['CALLBACK_URL'] ); // Generate checksum $checkSum = PaytmChecksum::generateSignature($paytmParams, $paytmConfig['KEY']); // Add checksum to the Paytm parameters $paytmParams["CHECKSUMHASH"] = $checkSum; ?>