/**
* @return string
*/
public function getPaymentSignature()
{
if (!$this->sum) {
throw new EmptySumException();
}
return $this->auth->getSignatureValue('{ml}:{ss}:{ii}{:cr}:{pp}{:cp}', ['ml' => $this->auth->getMerchantLogin(), 'ss' => $this->getShopSum(), 'ii' => $this->id, 'cr' => $this->currency, 'pp' => $this->auth->getPaymentPassword(), 'cp' => $this->getCustomParamsString()]);
}
