private function _checkUniqueID(Certificate $cert): bool
    {
        if (!$cert->tbsCertificate()->hasIssuerUniqueID()) {
            return false;
        }
        $uid = $cert->tbsCertificate()
            ->issuerUniqueID()
            ->string();
        if ($this->_issuerUID->string() != $uid) {
            return false;
        }
        return true;
    }