protected function processBlocktrailPubKeys() {
        if (!isset($this->backupInfo['blocktrail_public_keys'])) {
            return;
        }

        //create QR codes for each blocktrail pub key
        foreach ($this->backupInfo['blocktrail_public_keys'] as $keyIndex => $key) {
            $key = $key instanceof BIP32Key ? $key : BIP32Key::create(HierarchicalKeyFactory::fromExtended($key[0]), $key[1]);

            $qrCode = new QrCode();
            $qrCode
                ->setText($key->key()->toExtendedKey())
                ->setSize(self::QR_CODE_SIZE-20)
                ->setPadding(10)
                ->setErrorCorrection('high')
                ->setForegroundColor(array('r' => 0, 'g' => 0, 'b' => 0, 'a' => 0))
                ->setBackgroundColor(array('r' => 255, 'g' => 255, 'b' => 255, 'a' => 0))
                ->setLabel("KeyIndex: ".$keyIndex."    Path: ".$key->path())
                ->setLabelFontSize(10)
            ;
            $this->blocktrailPubKeyQRs[] = array(
                'keyIndex'  => $keyIndex,
                'path'      => $key->path(),
                'qr'        => $qrCode->getDataUri(),
                'qrImg'     => $qrCode->getImage(),
            );
        }
    }