Kerberos Login Module

public KerberosLoginModule extends LoginModule {
private KerberosUserPrincipal kup;
private KerberosTGTCredential ktc;
private Subject subj;
public void initialize (Subject s...) { subj=s; ... }
public boolean login() {
if (callbackHandler == null) { // no way to get parameters???
} else {
get username, pw, realm;
authenticate, remember kup and tkc;
}
}
public boolean commit() {
subj.getPrincipals.add(kup);
subj.getPublicCredentials.add(ktc);
}
}