CodeIgniter - PayTM integration

Paytm Payment Gateway enables users to accept payments from anyone, anywhere, from all channels and devices. It is the best Indian payment gateway that lets businesses collect customer payments via website, handheld devices like mobile and tablets, and social apps like WhatsApp, Facebook, or via email and SMS.

1. Create a checkout.php file in the applications/views/ directory.

<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>

2. Create a redirect.php file in the applications/views/ directory.

<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>

3. Create a config_paytm.php file in the applications/config/ directory.

Use PAYTM_ENVIRONMENT as ‘PROD’ if you wanted to do transactions in a production environment else ‘TEST’ for doing transactions in a 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.
The above details will be different for the testing and production environment.

<?php

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

$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);

?>

4. Create a Checkout.php file in the applications/controllers/ directory.

<?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 a transaction, etc.

5. Create an encdec_paytm_helper.php file in the applications/helpers/ directory.

<?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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