code: public static function generateChecksum1(int $orderId, Money $amount, string $sharedKey, int $currency): string
      {
          $amountAsFloat = (float)$amount->getAmount() / pow(10, 2);
  
          // the amount needs to be formatted as a danish number, so we convert the float
          $amount = number_format($amountAsFloat, 2, ',', '');
  
          return strtolower(md5($orderId.'+'.$amount.'+'.$sharedKey.'+'.$currency));
      }
docs: @param int    $orderId
  @param Money  $amount
  @param string $sharedKey
  @param int    $currency
  
  @return string