Creating keyring files for data encryption

[Stoyicker]

Hi there,

I've been reading about data encryption in this link.
My doubt comes in the end:

protected SecretKey lookupSecretKey(String id) {
    SecretKey key = null;

    // Get the key-ring file name from the property list for this agent
    String keyringFile = System.getProperty("keyring", "keyring.dat"); //IN THIS LINE

    // Try reading the key-ring and looking up the key for the id
    try {
        // Read the key-ring from disk
        ObjectInputStream in =
            new ObjectInputStream(new FileInputStream(keyringFile));
        Hashtable keyring = (Hashtable) in.readObject();
        // Lookup the id's key on the ring
        key = (SecretKey)keyring.get(id);
    }
    catch (Exception e) {
        System.err.println("Failure looking up key on keyring.");
        e.printStackTrace(System.err);
    }

    return key;
}

In the referred line, how am I supposed to generate a keyring? I've been 'googling' about the topic, but I can find nothing more that some IBM links that speak about some kind of software (owned by them, of course), that uses this kind of files.