if ( keys == null || keys.length == 0 ) {
            throw new KrbException("Could not find any keys in keytab for " + principalName); //$NON-NLS-1$
        }

        KrbAsReqBuilder builder = new KrbAsReqBuilder(principalName, keytab);
        Credentials creds = builder.action().getCreds();
        builder.destroy();

        return Krb5Util.credsToTicket(creds);
    }