Console cons = System.console();
                char[] password = (cons == null) ? null : cons.readPassword("Password: ");
                if (password != null) {
                    // Cipher uses Strings
                    passwd = String.copyValueOf(password);

                    // Sun/Oracle advises to empty the char array
                    java.util.Arrays.fill(password, ' ');
                }

        for (int i = 0; i < id.length(); i++) {
            char c = id.charAt(i);
            if (!isValidCoordinateIdCharacter(c)) {
                return false;
            }
        }
        return true;
    }

    private boolean isValidCoordinateIdCharacter(char c) {