function getPaymentArray($data)
{
    $payData = array('cac' => $data['Transaction']['Presentation']['Currency'], 'amount' => $data['Transaction']['Presentation']['Amount'], 'MsTxnId' => $data['Transaction']['Identification']['MsTxnId'], 'PspTxnId' => $data['Transaction']['Identification']['PspTxnId'], 'timeStamp' => $data['Transaction']['Processing']['Timestamp'], 'Result' => $data['Transaction']['Processing']['Result'], 'requestType' => 'payNote');
    $pay = new pay24($payData);
    $d = $pay->get_payment_data();
    return $d['Sign'];
}
 /**
  * Set message for 24pay gate
  *
  * @access private
  * @return void
  * @static
  */
 private static function get_message()
 {
     switch (self::$requestType) {
         case 'payRequest':
             self::$data = sha1(self::$mid . self::$amount . self::$cac . self::$MsTxnId . self::$firstName . self::$familyName . self::$timeStamp, true);
             break;
         case 'payNote':
             self::$data = sha1(self::$mid . self::$amount . self::$cac . self::$PspTxnId . self::$MsTxnId . self::$timeStamp . self::$Result, true);
             break;
     }
 }
<?php

date_default_timezone_set('America/Los_Angeles');
include_once './libs/24pay.class.php';
// ID USER IN APP
$idUser = 1;
$price = 15.55;
$debug = true;
$pData = array('email' => '*****@*****.**', 'amount' => $price, 'MsTxnId' => mt_rand(0, 99999999), 'requestType' => 'payRequest', 'clientid' => '*****@*****.**', 'firstName' => 'Roman', 'familyName' => 'Huliak');
$p24 = new pay24($pData);
$pubData = $p24->get_payment_data();
?>

<a href="https://github.com/roman-huliak/24-pay-payment-gate" target="_blank">https://github.com/roman-huliak/24-pay-payment-gate</a>
<br />
<a href="https://www.24-pay.sk/" target="_blank">https://www.24-pay.sk/</a>

<form id="payS" method="post" action="<?php 
echo $pubData['URL'];
?>
">
    <?php 
unset($pubData['URL']);
foreach ($pubData as $name => $value) {
    ?>
        <?php 
    echo $name;
    ?>
<input size="100" type="text" readonly="readonly" name="<?php 
    echo $name;
    ?>