function revoke($serial, $date = null)
    {
        if (isset($this->currentCert['tbsCertList'])) {
            if (is_array($rclist = &$this->_subArray($this->currentCert, 'tbsCertList/revokedCertificates', true))) {
                if ($this->_revokedCertificate($rclist, $serial) === false) { // If not yet revoked
                    if (($i = $this->_revokedCertificate($rclist, $serial, true)) !== false) {
                        if (!empty($date)) {
                            $rclist[$i]['revocationDate'] = $this->_timeField($date);
                        }

                        return true;
                    }
                }
            }
        }

        return false;
    }