};

        assertTrue(fessConfig.isValidUserCode("1234567890"));
        assertTrue(fessConfig.isValidUserCode("12345678901234567890"));
        assertTrue(fessConfig.isValidUserCode("1234567890abcdeABCD_"));

        assertFalse(fessConfig.isValidUserCode("123456789"));
        assertFalse(fessConfig.isValidUserCode("123456789012345678901"));
        assertFalse(fessConfig.isValidUserCode("123456789?"));
    }

        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final PrimaryCipher cipher = ComponentUtil.getPrimaryCipher();
        userCode = cipher.encrypt(userCode);
        if (fessConfig.isValidUserCode(userCode)) {
            return userCode;
        }
        return null;
    }

    /**
     * Deletes the user code cookie from the client browser.