I am taking an exam during which any materials or electronic devices are allowed, provided that I can demonstrate that they cannot be used for communicating with others. I want to take my Android tablet and use it to display PDF files that I don't want to print out.

I need to come up with a way how to temporary turn a Nexus 7 Android tablet from a communication device into a book reader incapable of connecting to WiFi. I need to be able to quickly prove to the teacher that this is so and that whatever I do it will remain in this mode during the exam.

Do you have any ideas how this can be achieved? My belief is that this is impossible, but I decided to ask anyway.

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    Welcome to the site! Interesting question, but I don't think this would be possible. How would you prove that you can't/won't just enable it during the test?
    – dotVezz
    Commented Nov 11, 2013 at 14:29
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    Even if it would be possible: it's easy to prove you can do something. But it's impossible to prove you cannot. Even proving it's not possible by normal means, you could have placed an unusual backdoor somehow.
    – Izzy
    Commented Nov 11, 2013 at 15:51
  • @Izzy When I said 'prove', I meant some reasonable scheme that would allow the other party to form a well founded belief in a short amount of time that it is indeed the case. I also assume that the other party is reasonably forthcoming and would not assume treachery on my part in places that do not provide obvious opportunities for it.
    – user7610
    Commented Nov 11, 2013 at 19:07
  • I could not come up with anything in Android. If Android had something like UEFI secure boot, I could put teacher's key into the device, get a an offline only ROM from him, load the ROM into the device and before the teacher could verify that the key is still his (and therefore it has not been tampered with the system). Other possibility I come up with is cover the tablet in wire mesh that serves as Faraday cage. I can see through it the screen and plug in USB mouse (because I wouldn't be able to touch the screen). But EM shielding is tricky stuff and I have no real experience with it.
    – user7610
    Commented Nov 11, 2013 at 19:12
  • Your last comment was very close, and knocked free what was lurking behind the curtains of my thoughts: I was sure there was something, but couldn't get to its core, until you opened the door with the "key" (literally, as it was that word, in combination with "secure" and your previous-to-last comment almost describing a parent-child-relation :)
    – Izzy
    Commented Nov 11, 2013 at 20:53

1 Answer 1


As no "bullet-proof" system is required here, and at least some level of trust assumed, possible solutions hide behind the buzz... ahem, key-words and child-protection. In short: you create a "jail" you're working in, and hand it's key (password) to the teacher (let him/her set a password – of course on the premise to unlock you once the exam is over).

Options on establishing a kiosk-mode are already discussed in several other questions tagged "kiosk-mode", so there's no need to repeat them all. You might wish to take a look at SureLock Kiosk Lockdown, which should meet your requirements: one of its features is to prevent access to system settings. So disabling all network features (mobile data, WiFi APNs, etc.) and then locking the settings with the teacher's password should satisfy both sides – provided you've allowed all required apps for kiosk mode. As the "dirty trick" to regain control would also remove all data from the device (factory-reset), it cannot be expected you'd do that during the exam ;)

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