Can localstorage values be modified outside app?

Question

I am developing mobile app using jQuery mobile and phonegap. In that I have developed user login functionality and maintained loged in user id in localstorage, So I can relate user activities.

My application is working correctly, But I am worried about external modifications in localstorage. Can it be possible to modify localstorage values outside application.

Code In app : localStorage.setItem("userid", 60);

Can user modify it manually Or it is safe to use?

Answer 1

If it is any kind of secured data, then it is safe to use Shared Preference in android.

SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor editor = settings.edit();
editor.putString("KEY","VALUE");
editor.commit();

You can access it by plugin.

Similar question is asked here go through it - How to store a json data securely in phonegap android?

Answer 2

The localStorage saves it's key/value pairs per domain ( Same-origin-policy ). Since a phonegap app will get its own "domain" you do not need to be worried about other apps modifying your variables.

Also see this question right here: In HTML5, is the localStorage object isolated per page/domain?

Nevertheless, I would recommend to not save any sensible data on the client side, it would be better to do this on the server.