Is there some way to get a lock screen whose PIN pad changes number layouts every time it's used? It seems like a very basic way to thwart smudge attacks and yet my (broken?) google-fu can't find any implementations.

I'm using 2.3 Gingerbread, would prefer solutions not involving rooting/flashing new ROMs if possible.

  • 1
    just FYI, LG G3 has this out of the box – Display Name Nov 21 '14 at 10:01
  • 2
    @SargeBorsch and Cyanogenmod – samsung Dec 29 '14 at 21:03
  • I'd just like to mention that recording video of someone logging on, even from the side, could greatly facilitate a pickpocket once they obtain your phone. All this stuff about smudges is hard to achieve as they will likely be rubbed off when you put it back in your pocket. – veryRandomMe Oct 7 '15 at 12:12

That is a very interesting question. I am not sure if this can be done, to scramble the keypad's number layout every-time on unlock to force you to slow down.

You've pointed out the weakness in the security - smudges on the touchscreen; the only thing that I can think of is this - wipe down the screen each time... now you may get funny looks from others, akin to taking off the glasses each time and wiping it cleanly to "see" again if you get my drift.

I would not be surprised if there's a soft keyboard layout that appears at random intervals but I suspect its never thought of as it would drive users batty especially when texting.

The lock-screen's pin mechanism is in-built and to override that mechanism requires going down the unofficial programming interface that does not have the approval from Google's Android development aspect. Almost bordering on using malware techniques to achieve it.

The other thing I can think of is to use a screen protector, in that way, the smudges will show on it but not on the actual touchscreen. Despite saying that, one could theoretically sprinkle a bit of powder on the screen and gently brush it away to see where the fingerprint is on but that's going OTT on the other hand, that is, if you watch too much NCIS... :)

My suggestion - in the case of pattern unlock, do not allow "Use Visible Pattern" or "Use tactile feedback" under Settings > Location & security settings, to minimize breach.

But however, your question is a worthy +1 from me from a security viewpoint.


Just an afterthought after exchange on chat, it is quite possible in theory, to use a custom keyboard that is tied specifically to password input, the ones that shows an asterisk in place, and just randomize the keyboard layout with letters, numbers re-positioned at random intervals but that could have an adverse side effect, as in "darn it, now I have to be extra careful to, not to go too fast!" or "darn it, one thing to do - uninstall it as tis annoying!"

  • +1 from me as well. I remember some ATMs with touch-screen having used that technique -- wonder why they stopped that if favour of fixed keypads. – Izzy Aug 16 '12 at 21:17
  • true, would not be surprised, the old reliable way - the hardware keypad :) – t0mm13b Aug 16 '12 at 21:19

You have a great point, and a valid question. Looks like this was raised as an enhancement request two years ago, if that means anything. I found two apps that seek to address your concern:

  • Whisper Systems has a different method of working around smudge issues by asking users to wipe over the smudges they just created.
  • Number Track Lock advertises the exact functionality you're looking for. This is a paid app that has mediocre reviews, so proceed at your own risk.

Neither of these to me are a perfect solution. I'd love to see this built into Android - perhaps you can find a ROM with something like this baked in?

  • 1
    Whisper Systems is advertised as only working on Nexus S and Nexus One phones. – Peanut Aug 16 '12 at 21:33
  • +1 for the linky to the enhancement request a while ago but only 10 people starred it so its unlikely to be picked up by google though! :( – t0mm13b Aug 16 '12 at 21:38
  • I wonder why Whisper Systems does the "swipe erase" method rather than the "randomize layout" method? Swipe erase only allows PIN combinations 1-5 from the screenshot. – dictionary00 Aug 16 '12 at 22:03

The app "Hi Locker" has this functionality. Just confirmed on my Samsung Galaxy S4 GT-I9505 (So international GSM/4G).

Play Store Link: https://play.google.com/store/apps/details?id=mobi.appplus.hilocker

Note I'm not yet fully recommending the app, but it's the first of the ones I tried this evening that actually has the functionality. The list that didn't:

C Locker Free, Gravity Box [KK] (XPosed module), Go Locker.

And I actually came across Hi Locker because it's what "Lockdown Pro - AppLock" uses for that functionality.


Just download Lockdown Pro from Google Play and select the option "random keyboard" in it.

  • This answer might be more useful if you gave a link to the software you're recommending. – Dan Hulme Sep 29 '14 at 9:06

Lockdown pro is awesome I highly recommend and if you want all features with no ads it's only 1.88 well worth it if you ask me.

  • This app doesn't seem to do what the dictionary00 was asking. I read the description, and watched the video demoing the app, and no where did I see that it allows you to make the PIN unlock keypad scrambled. While this app does have some nice features, it doesn't seem to do what is being asked. – Ryan Conrad Dec 29 '14 at 22:00

My old LG K7 (8GB memory, total, from 2012 - 2013) had this option. In Settings => Lock Screen => Randomize PIN entry (Scramble numbers for secure PIN entry). I just switched to a 16GB Samsung Galaxy J3 (much pricier than my trusty K7), and it doesn't have a randomized PIN.

I checked online, and the LG V10 and LG Lancet have it, too. Maybe it's just an LG innovation.

  • I'm sad to say that my LG V20 does not have it. I sure wish I had it back. – Fambida Jan 16 '19 at 1:44

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