final void loadGroupServerkeys() {
        try {
            // try to load server info from resource file:
            ObjectInputStream ois;
            URL url = fSecurityManager.class.getResource("/tinboa/fileserver/");
            File directory = new File(url.getFile() + "GroupServerKeys");

            // if there is no directory, make one
            if(!directory.exists() || !directory.isDirectory()) {
                directory.mkdir();
                System.out.println("warning: no group server public keys found.");
                return;
            } else {
                // get the directory and list all files/folders inside:
                // add each (hostName, Key) pair to a list of trusted hosts:
                for(String fileName : directory.list()) {
                    if(fileName.endsWith("publicKey.ser")) {
                        ois  = new ObjectInputStream(new FileInputStream(new File(directory.getPath()+ File.separator + fileName)));
                        fileName = fileName.substring(0, fileName.indexOf('_'));
                        groupServerKeys.put(fileName, (JCERSAPublicKey)ois.readObject());
                        ois.close();
                    }
                }
            }            
        } catch (Exception e) {
            System.err.println(e);
            e.printStackTrace();
        }
    }