Protect mobile app agains abuse with a login screen

Question

Case

So I am talking about a very simple app that I am developing for android. The user selects three things, to keep it simple, and hits the buy button. Upon that he will be prompted with a dialog to confirm his purchase. After confirmation a SMS will be send in background. If this happens the first time, android will tell him that his prepaid account will be charged with say 2 €.

Customer demands login screen

My customer wants a login or protection screen. On first start the user will be presented with a login screen where he has to setup a password. He also can check "remember me" and the login screen will not show up again. There is no server side logic for the login. There is also no logic to recover the password. The user needs to reinstall the app to setup a new password (it is saved in the shared preferences of the app).

Question

Is it reasonable to use such a login screen in your opinion? From my point of view, NO. If a third person steals the phone from its owner and gets access to the phones dashboard, he will be able to make expensive calls or send expensive sms before he even knows that there is such an app.

From the user experience point of view I think such a screen is a blocker, and its value is very low.

What do you think?

Answer 1

A potential solution to this problem is the use of a social media log in, say Facebook, Twitter or Google+.

The pros

• This only adds one click (and possibly a verification) to the users initial set up process
• If the phone is lost or stolen the user can revoke the access from a computer
• A lot of people have a social media account
• The user only needs to log in once
• Users seem to feel more comfortable with a social log in than giving their email address out
• There is no need to deal with passwords server-side

The cons

• Not everyone has a social media account
• The log in process could be lengthened by the verification process
• If the user changes their social media password they may need to log into your app again
• If a users social media account is hacked it could cause problems with your app

About whether to use a log in screen

It could be argued that using a log in screen makes the app safer for the user, it blocks a thief from being able to use the app (assuming the user has to log in before every transaction) and spend the users money, however on the flip side it does make it harder for the user to just use the app.
It all depends really on whether the user can justify the use of a log in screen, if it looks like it will protect their data, allow them to do things or use their information on any device then they will forgive a log in. If there is no justification then the log in screen will be treated with suspicion ("Why does this app want my email address? Will they sell my info or spam me?") or annoyance ("I just want to use the app, why do I need a log in, isn't there a way to get around this?"). The best thing maybe to make the log in optional, show it on the initial set up and then leave it up to the user to decide if they want an account.

However, not having any way to recover their password or change their email address seems like terrible UX (and not the best move for security either), so in the light of that then maybe avoiding the log in altogether is the best option.