// "Hello" encoded in standard Base64
        final byte[] result = authenticator.decodeBase64("SGVsbG8=");
        assertEquals("Hello", new String(result));
    }

    @Test
    public void test_decodeBase64_urlSafe() {
        // Base64 URL encoding (uses - and _ instead of + and /)
        final byte[] result = authenticator.decodeBase64("SGVsbG9Xb3JsZA");
        assertEquals("HelloWorld", new String(result));
    }