If user A inputs credentials into a mobile app (first name, last name, Email ID and reference number) in order to unlock the app; whats the best way to prevent user B from inputting the same credentials as User A onto their mobile device in order to unlock the app? (Both user A and B having the same app installed on their devices).

I'm thinking IMEI and storing that information on a central database but is that possible in hybrid app and is there another way without IMEI?

1 Answer 1


The problem with this is that if User A loses their phone or has it stolen, they would no longer be able to log into your app on their replacement device. Plus, the same user having multiple devices is becoming more and more common.

Is there a reason why you can't just use email & password? Even if you need to collect all that info at least once, can't it then be secured by password for if the user needs to log in on a different device?

  • Thanks, yes we could consider that but what if User B attempts to input the same username and password as user A?
    – user85975
    Jun 11, 2016 at 16:17
  • 1
    @user8575 User B shouldn't have User A's login info, unless User B is a hacker or User A shared their details with User B. Jun 13, 2016 at 19:10

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