Payment Gateway Integration using PayTM in CodeIgniter

PayTM Payment Gateway Integration in CodeIgniter

In this example, I am going to show you how to integrate PayTM Payment Gatway in the CodeIgniter framework PHP.

Here, we are using 5 files for Payment Gateway Integration file:

Controller:      Checkout.php    application\controllers\Checkout.php
Views:          checkout.php    application\views\checkout.php
Views:          redirect.php    application\views\redirect.php
Helpers:          encdec_paytm_helper.php    application\helpers\encdec_paytm_helper.php
Constants:      config_paytm.php    application\config\config_paytm.php

For Payment Gateway Sign up on Business with PayTM

PayTM Payment Gateway Integration in CodeIgniter

application\views\checkout.php

<form method="post" action="<?php echo base_url('pay'); ?>">
	<table border="1">
		<tbody>
			<tr>
				<th>S.No</th>
				<th>Label</th>
				<th>Value</th>
			</tr>
			<tr>
				<td>1</td>
				<td>
					<label>ORDER_ID::*</label>
				</td>
				<td>
					<input id="ORDER_ID" tabindex="1" maxlength="20" size="20" name="ORDER_ID" autocomplete="off" value="<?php echo  " ORDS " . rand(10000,99999999)?>">
				</td>
			</tr>
			<tr>
				<td>2</td>
				<td>
					<label>CUSTID ::*</label>
				</td>
				<td>
					<input id="CUST_ID" tabindex="2" maxlength="12" size="12" name="CUST_ID" autocomplete="off" value="CUST001">
				</td>
			</tr>
			<tr>
				<td>3</td>
				<td>
					<label>INDUSTRY_TYPE_ID ::*</label>
				</td>
				<td>
					<input id="INDUSTRY_TYPE_ID" tabindex="4" maxlength="12" size="12" name="INDUSTRY_TYPE_ID" autocomplete="off" value="Retail">
				</td>
			</tr>
			<tr>
				<td>4</td>
				<td>
					<label>Channel ::*</label>
				</td>
				<td>
					<input id="CHANNEL_ID" tabindex="4" maxlength="12" size="12" name="CHANNEL_ID" autocomplete="off" value="WEB">
				</td>
			</tr>
			<tr>
				<td>5</td>
				<td>
					<label>txnAmount*</label>
				</td>
				<td>
					<input title="TXN_AMOUNT" tabindex="10" type="text" name="TXN_AMOUNT" value="1">
				</td>
			</tr>
			<tr>
				<td></td>
				<td></td>
				<td>
					<input value="CheckOut" type="submit" onclick="">
				</td>
			</tr>
		</tbody>
	</table>* - Mandatory Fields
</form>

application\views\redirect.php

<html>
<head>
<title>Merchant Check Out Page</title>
</head>
<body>
	<center><h1>Please do not refresh this page...</h1></center>
		<form method="post" action="<?php echo PAYTM_TXN_URL ?>" name="f1">
		<table border="1">
			<tbody>
			<?php
			foreach($paramList as $name => $value) {
				echo '<input type="hidden" name="' . $name .'" value="' . $value . '">';
			}
			?>
			<input type="hidden" name="CHECKSUMHASH" value="<?php echo $checkSum ?>">
			</tbody>
		</table>
		<script type="text/javascript">
			document.f1.submit();
		</script>
	</form>
</body>
</html>

application\config\config_paytm.php

Use PAYTM_ENVIRONMENT as 'PROD' if you wanted to do transaction in production environment else 'TEST' for doing transaction in testing environment.

Change the value of PAYTM_MERCHANT_KEY constant with details received from Paytm.
Change the value of PAYTM_MERCHANT_MID constant with details received from Paytm.
Change the value of PAYTM_MERCHANT_WEBSITE constant with details received from Paytm.
Above details will be different for testing and production environment.

<?php

define('PAYTM_ENVIRONMENT', 'PROD'); // PROD
define('PAYTM_MERCHANT_KEY', ''); //Change this constant's value with Merchant key received from Paytm.
define('PAYTM_MERCHANT_MID', ''); //Change this constant's value with MID (Merchant ID) received from Paytm.
define('PAYTM_MERCHANT_WEBSITE', 'DEFAULT'); //Change this constant's value with Website name received from Paytm.

$PAYTM_STATUS_QUERY_NEW_URL='https://securegw-stage.paytm.in/merchant-status/getTxnStatus';
$PAYTM_TXN_URL='https://securegw-stage.paytm.in/theia/processTransaction';

if (PAYTM_ENVIRONMENT == 'PROD') {
	$PAYTM_STATUS_QUERY_NEW_URL='https://securegw.paytm.in/merchant-status/getTxnStatus';
	$PAYTM_TXN_URL='https://securegw.paytm.in/theia/processTransaction';
}

define('PAYTM_REFUND_URL', '');
define('PAYTM_STATUS_QUERY_URL', $PAYTM_STATUS_QUERY_NEW_URL);
define('PAYTM_STATUS_QUERY_NEW_URL', $PAYTM_STATUS_QUERY_NEW_URL);
define('PAYTM_TXN_URL', $PAYTM_TXN_URL);

?>

application\controllers\Checkout.php

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Checkout extends CI_Controller {

	public function __construct() {

		parent::__construct();

	}

	public function checkout() {

		$this->load->view('checkout');

	}

	public function pay() {
		$checkSum 	= "";
		$paramList 	= array();

		$ORDER_ID 			= $this->input->post("order_id");
		$CUST_ID 			= $this->input->post("user_id");
		$INDUSTRY_TYPE_ID 	= $this->input->post("industry_type_id");
		$CHANNEL_ID 		= $this->input->post("channel_id");
		$TXN_AMOUNT 		= $this->input->post("amount");

		// Create an array having all required parameters for creating checksum.
		$paramList["MID"] 				= PAYTM_MERCHANT_MID;
		$paramList["ORDER_ID"] 			= $ORDER_ID;
		$paramList["CUST_ID"] 			= $CUST_ID;
		$paramList["INDUSTRY_TYPE_ID"] 	= $INDUSTRY_TYPE_ID;
		$paramList["CHANNEL_ID"] 		= $CHANNEL_ID;
		$paramList["TXN_AMOUNT"] 		= $TXN_AMOUNT;
		$paramList["WEBSITE"] 			= PAYTM_MERCHANT_WEBSITE;
		$paramList["CALLBACK_URL"] 		= base_url('response');

		//Here checksum string will return by getChecksumFromArray() function.
		$data['checkSum'] = getChecksumFromArray($paramList, PAYTM_MERCHANT_KEY);
		$data['paramList'] = $paramList;
		
		$this->load->view('redirect', $data);
	}

	public function response() {
		$paytmChecksum 		= "";
		$paramList 			= array();
		$isValidChecksum 	= "FALSE";

		$paramList = $_POST;
		$paytmChecksum = isset($_POST["CHECKSUMHASH"]) ? $_POST["CHECKSUMHASH"] : ""; //Sent by Paytm pg

		$isValidChecksum = verifychecksum_e($paramList, PAYTM_MERCHANT_KEY, $paytmChecksum); //will return TRUE or FALSE string.

		if($isValidChecksum == "TRUE") {

			if ($_POST["STATUS"] == "TXN_SUCCESS") {
				echo "<b>Transaction status is success</b>" . "<br/>";
			} else {
				echo "<b>Transaction status is failure</b>" . "<br/>";
			}

			if (isset($_POST) && count($_POST)>0 ) {
				foreach($_POST as $paramName => $paramValue) {
        			echo "<br/>" . $paramName . " = " . $paramValue;
        		}
			}
		} else {
			echo "<b>Checksum mismatched.</b>";
		}

	}

}

Verify all parameters received from Paytm pg to your application. Like MID received from paytm pg is same as your application’s MID, TXN_AMOUNT and ORDER_ID are same as what was sent by you to Paytm PG for initiating transaction etc.

application\helpers\encdec_paytm_helper.php

<?php
				    
function encrypt_e($input, $ky) {
	$key   = html_entity_decode($ky);
	$iv = "@@@@&&&&####$$$$";
	$data = openssl_encrypt ( $input , "AES-128-CBC" , $key, 0, $iv );
	return $data;
}

function decrypt_e($crypt, $ky) {
	$key   = html_entity_decode($ky);
	$iv = "@@@@&&&&####$$$$";
	$data = openssl_decrypt ( $crypt , "AES-128-CBC" , $key, 0, $iv );
	return $data;
}

function generateSalt_e($length) {
	$random = "";
	srand((double) microtime() * 1000000);

	$data = "AbcDE123IJKLMN67QRSTUVWXYZ";
	$data .= "aBCdefghijklmn123opq45rs67tuv89wxyz";
	$data .= "0FGH45OP89";

	for ($i = 0; $i < $length; $i++) {
		$random .= substr($data, (rand() % (strlen($data))), 1);
	}

	return $random;
}

function checkString_e($value) {
	if ($value == 'null')
		$value = '';
	return $value;
}

function getChecksumFromArray($arrayList, $key, $sort=1) {
	if ($sort != 0) {
		ksort($arrayList);
	}
	$str = getArray2Str($arrayList);
	$salt = generateSalt_e(4);
	$finalString = $str . "|" . $salt;
	$hash = hash("sha256", $finalString);
	$hashString = $hash . $salt;
	$checksum = encrypt_e($hashString, $key);
	return $checksum;
}
function getChecksumFromString($str, $key) {
	
	$salt = generateSalt_e(4);
	$finalString = $str . "|" . $salt;
	$hash = hash("sha256", $finalString);
	$hashString = $hash . $salt;
	$checksum = encrypt_e($hashString, $key);
	return $checksum;
}

function verifychecksum_e($arrayList, $key, $checksumvalue) {
	$arrayList = removeCheckSumParam($arrayList);
	ksort($arrayList);
	$str = getArray2StrForVerify($arrayList);
	$paytm_hash = decrypt_e($checksumvalue, $key);
	$salt = substr($paytm_hash, -4);

	$finalString = $str . "|" . $salt;

	$website_hash = hash("sha256", $finalString);
	$website_hash .= $salt;

	$validFlag = "FALSE";
	if ($website_hash == $paytm_hash) {
		$validFlag = "TRUE";
	} else {
		$validFlag = "FALSE";
	}
	return $validFlag;
}

function verifychecksum_eFromStr($str, $key, $checksumvalue) {
	$paytm_hash = decrypt_e($checksumvalue, $key);
	$salt = substr($paytm_hash, -4);

	$finalString = $str . "|" . $salt;

	$website_hash = hash("sha256", $finalString);
	$website_hash .= $salt;

	$validFlag = "FALSE";
	if ($website_hash == $paytm_hash) {
		$validFlag = "TRUE";
	} else {
		$validFlag = "FALSE";
	}
	return $validFlag;
}

function getArray2Str($arrayList) {
	$findme   = 'REFUND';
	$findmepipe = '|';
	$paramStr = "";
	$flag = 1;	
	foreach ($arrayList as $key => $value) {
		$pos = strpos($value, $findme);
		$pospipe = strpos($value, $findmepipe);
		if ($pos !== false || $pospipe !== false) 
		{
			continue;
		}
		
		if ($flag) {
			$paramStr .= checkString_e($value);
			$flag = 0;
		} else {
			$paramStr .= "|" . checkString_e($value);
		}
	}
	return $paramStr;
}

function getArray2StrForVerify($arrayList) {
	$paramStr = "";
	$flag = 1;
	foreach ($arrayList as $key => $value) {
		if ($flag) {
			$paramStr .= checkString_e($value);
			$flag = 0;
		} else {
			$paramStr .= "|" . checkString_e($value);
		}
	}
	return $paramStr;
}

function redirect2PG($paramList, $key) {
	$hashString = getchecksumFromArray($paramList);
	$checksum = encrypt_e($hashString, $key);
}

function removeCheckSumParam($arrayList) {
	if (isset($arrayList["CHECKSUMHASH"])) {
		unset($arrayList["CHECKSUMHASH"]);
	}
	return $arrayList;
}

function getTxnStatus($requestParamList) {
	return callAPI(PAYTM_STATUS_QUERY_URL, $requestParamList);
}

function getTxnStatusNew($requestParamList) {
	return callNewAPI(PAYTM_STATUS_QUERY_NEW_URL, $requestParamList);
}

function initiateTxnRefund($requestParamList) {
	$CHECKSUM = getRefundChecksumFromArray($requestParamList,PAYTM_MERCHANT_KEY,0);
	$requestParamList["CHECKSUM"] = $CHECKSUM;
	return callAPI(PAYTM_REFUND_URL, $requestParamList);
}

function callAPI($apiURL, $requestParamList) {
	$jsonResponse = "";
	$responseParamList = array();
	$JsonData =json_encode($requestParamList);
	$postData = 'JsonData='.urlencode($JsonData);
	$ch = curl_init($apiURL);
	curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");                                                                     
	curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);                                                                  
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
	curl_setopt ($ch, CURLOPT_SSL_VERIFYHOST, 0);
	curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, 0);
	curl_setopt($ch, CURLOPT_HTTPHEADER, array(                                                                         
	'Content-Type: application/json', 
	'Content-Length: ' . strlen($postData))                                                                       
	);  
	$jsonResponse = curl_exec($ch);   
	$responseParamList = json_decode($jsonResponse,true);
	return $responseParamList;
}

function callNewAPI($apiURL, $requestParamList) {
	$jsonResponse = "";
	$responseParamList = array();
	$JsonData =json_encode($requestParamList);
	$postData = 'JsonData='.urlencode($JsonData);
	$ch = curl_init($apiURL);
	curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");                                                                     
	curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);                                                                  
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
	curl_setopt ($ch, CURLOPT_SSL_VERIFYHOST, 0);
	curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, 0);
	curl_setopt($ch, CURLOPT_HTTPHEADER, array(                                                                         
	'Content-Type: application/json', 
	'Content-Length: ' . strlen($postData))                                                                       
	);  
	$jsonResponse = curl_exec($ch);   
	$responseParamList = json_decode($jsonResponse,true);
	return $responseParamList;
}
function getRefundChecksumFromArray($arrayList, $key, $sort=1) {
	if ($sort != 0) {
		ksort($arrayList);
	}
	$str = getRefundArray2Str($arrayList);
	$salt = generateSalt_e(4);
	$finalString = $str . "|" . $salt;
	$hash = hash("sha256", $finalString);
	$hashString = $hash . $salt;
	$checksum = encrypt_e($hashString, $key);
	return $checksum;
}
function getRefundArray2Str($arrayList) {	
	$findmepipe = '|';
	$paramStr = "";
	$flag = 1;	
	foreach ($arrayList as $key => $value) {		
		$pospipe = strpos($value, $findmepipe);
		if ($pospipe !== false) 
		{
			continue;
		}
		
		if ($flag) {
			$paramStr .= checkString_e($value);
			$flag = 0;
		} else {
			$paramStr .= "|" . checkString_e($value);
		}
	}
	return $paramStr;
}
function callRefundAPI($refundApiURL, $requestParamList) {
	$jsonResponse = "";
	$responseParamList = array();
	$JsonData =json_encode($requestParamList);
	$postData = 'JsonData='.urlencode($JsonData);
	$ch = curl_init($apiURL);	
	curl_setopt ($ch, CURLOPT_SSL_VERIFYHOST, 0);
	curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, 0);
	curl_setopt($ch, CURLOPT_URL, $refundApiURL);
	curl_setopt($ch, CURLOPT_POST, true);
	curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);  
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
	$headers = array();
	$headers[] = 'Content-Type: application/json';
	curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);  
	$jsonResponse = curl_exec($ch);   
	$responseParamList = json_decode($jsonResponse,true);
	return $responseParamList;
}

?>

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