protected function GetMontradaResponseHash($aInput)
    {
        $sDelimiter = '-';

        $sString = $this->GetConfigParameter('secret').$sDelimiter;
        $sString .= $this->GetConfigParameter('merchid').$sDelimiter;
        $sString .= $aInput['orderid'].$sDelimiter;
        $sString .= $aInput['amount'].$sDelimiter;
        $sString .= $aInput['currency'].$sDelimiter;
        $sString .= $aInput['result'].$sDelimiter;
        if (array_key_exists('trefnum', $aInput) && !empty($aInput['trefnum'])) {
            $sString .= $aInput['trefnum'].$sDelimiter;
        }
        $sString .= $aInput['timestamp'];

        return hash('sha256', $sString);
    }