How safe is AccountManager for storing app state data (like Pro status)?

Question

I have inherited an app which comes as a free version, and Pro monthly subscription is bought via in-app items. The Pro status (a simple string "pro_status") is saved inside the AccountManager (package android.accounts).

//AccountManager initiated
AccountManager mAccountManager = AccountManager.get(this);
//fetch accounts which correspond to our package name
Account[] accounts = mAccountManager.getAccountsByType(getString(R.string.account_type));
//save Pro status inside the AccountManager
mAccountManager.setUserData(mAccount, "is_pro", "" + info.isPro());

The app suffers from a strange bug that it forgets the Pro state randomly, either when you close the app or during the work.

Is this a good way to store Pro status? Could AccountManager be the reason why the app loses the idea of a Pro status?

I usually use either a database or SharedPreferences to store such data (besides storing it on the remote API), so I need a help from someone who used his app in the same way.

Answer 1

Usually the people playing with the setting "pro" status will be the one with rooted devices. Anyways the data stored in the account manager is visible to such users.

So, for such a use case, even account manager is not safe. Though other apps (with different UID) cannot access this data.

Also keep in mind that the user can delete the account from the settings which might be the reason for your settings going away.

My advice would be save this info in shared pref in encrypted form??

Answer 2

In all phones,there is a specific User Database which stores information regarding your accounts.

Is this a good way to store Pro status?

I cannot answer that however I can give you answer to related questions

Is it modifiable?

There are 2 ways of accessing this data, viz  

1. The user explicitly gives permission to an application to read account details for that particular account. This list of apps which can access the details for this account are stored based on PIDs,which cannot be same for different apps. check setUserData and AUTHENTICATE_ACCOUNTS permission

2. This database can be accessed(and modified ) on a rooted device.

Can a user manually delete this data?

-Yes,He can delete the account from the device itself.It is his device and he can modify any account details on it too.

In my experiece,the Acccount Manager API is very temperamental, and prone to change which can break your code if it is not used in the way that it was intended to be i.e. store User Account details in centralised database.

You should look into the approach and comments(but not the answer) of this question . I agree with the shared preferences approach too.