CODEWITHSUNDEEP
androidpassword-protection
Carsten Drösser
Carsten Drösser

Reputation: 496

Android: Lock app with password

I want to lock my application with a password which the user has set in the applications settings. Each time the main acitivity of my app is going to be shown, a password dialog should be shown instead. I know how to do that, but i wonder... :

How do I store the password the user has set? I can't store it in SharedPreferences because you can delete SharedPreferences in your phone's settings. I thought about a textfile which holds the password, but this file can be deleted, cant it? Any ideas?

Upvotes: 3

Views: 2238

Answers (2)

Bart Friederichs
Bart Friederichs

Reputation: 33511

One option is to put the password in the same file as where you have the other information (I reckon you want to protect the settings/data of the user). Just do not start the app when that file is missing or corrupted. What you have accomplished then, is that the information is rendered unusable if someone tampers with the data. Sign / encrypt your data file(s).

Another solution could be to store the password (hash!) on a webserver.

Upvotes: 0

mah
mah

Reputation: 39807

You cannot protect against the password being deleted one way or another, so you need to step back and consider why you have a password in the first place. Most likely you're using the password to protect data the app has access to, rather than the actual app itself (since protecting the app from running is not going to be effective against an attacker that has physical access to the device.

If your password is to protect data, you only need to ensure that an attacker cannot access the data due to deleting a password store. One way to do this is to use the password as an encryption key (or part of a key) that obscures the data -- thus there's not even a password to delete.

Upvotes: 2

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