How to securely dispose of a smartphone?

Question

How to dispose of a smartphone (it's an iPhone 5) at home? I was reading through this SE site questions and found this one which hardly applies here. Besides, I'd want to do it so that:

• It's not damaging the ecology (at least not too much)
• I don't have to do it with work tools (I don't have a hammer and surely don't want to set anything on fire in my apartment)

The device is currently in use for all sort of things - 2factor auth, custom authenticators, personal data, banks eTAN etc etc.

After the disposal, the data from the device must be impossible to restore and the device should be impossible to use as anything but decoration.

Answer 1

Unless you have secrets on that phone that someone would pay a lot of money to uncover, you don't need to go overboard. A factory reset would work just fine.

To decrease the chances someone would still recover something, point the camera out of the window and let it record until it fills up all memory. Repeat if you want. Doing that will overwrite almost everything, and anything it could be recovered will mean too little to be of any use.

But if you have secrets that would make someone use a electron microscope on it, rent a clean room or spend hundreds of times the price of your phone to recover its data, physical destruction is the only safe option.

Answer 2

Under the assumption that you have a somewhat recent phone (Android 6+ installed from factory, I don't know for Apple but read something about from iPhone 6 on):

• Wipe the phone/do a factory reset (assuming the phone is still working)

Modern devices always encrypt all the data and only delete the key for this encryption if you wipe it. This makes it impossible to restore data after wiping.

Answer 3

Under the assumption you do not trade state secrets I would:

• Wipe the phone/do a factory reset (assuming the phone is still working)
• Remove the SD Card (keep it for later use) (does not apply to the iPhone5, since it has none)
• Open the phone
• Locate the motherboard (the largest piece of printed circuit board)
• Unseat or destroy the following chips as possible (See this iPhone5 Teardown Guide on iFixit for details):
  • Hynix H2JTDG2MBR 128 Gb (16 GB) NAND flash (on Step 15)
  • The A6 processor (on Step 16/18)
• Dispose the parts at different times/different locations of an electronics recycling shop (Availability depends on country)

With this, an reassembly and successful extraction of data would be expensive and very unlikely.

Note: According to the iPhone Wiki, the A6 does not have a Secure Enclave, so nothing to do about that.

Answer 4

"Impossible to restore" can only be securely achieved by physically destroying chips.

Which one, depends on the device and an optional encryption. (By that I mean, if the flash storage on the device is encrypted and the encryption-key secured with a second chip, it would be sufficient to destroy one of them, to bring the data to an unrecoverable state).

If you don't physically destroy the chips and the storage is not encrypted, or the device has been somehow compromised before, then it may be possible to restore the data, even if you destroy other parts of the device. That recovery could be simple and cheap (e.g., simply speaking, by resoldering the flash chip onto another device of the same model; Cost: 70$ in a specialized lab), or super-hard (extensive forensics), depending on many factors. This depends especially on the exact flash storage type.

For a 'impossible to restore for an average person' - type security, it should be sufficient to wipe and factory-reset the phone two or three times, to be certain that the system is not storing any backup files.

Also - like Marcel already wrote - make sure to remove the SD card!

Answer 5

A factory reset is notoriously not enough to really wipe your data from a phone. See for instance https://www.androidpit.com/why-a-factory-reset-doesn-t-wipe-all-your-data for Android, or https://support.apple.com/lv-lv/HT201351 for iphone. Really, your problem is lack of googling here :-). Do a factory reset, but also follow whatever current advice you can find about your specific OS.

Of course you can destroy the phone physically. But it's a better solution to donate it to an organization that can pass it on to someone who'd be happy with an older phone. Either way, you need to make sure your data is thoroughly wiped before you go on.

Answer 6

Factory reset it and then take it to an Apple store (if you have one close by) and ask them to recycle/dispose of it.

Apple trade-in/Recycle

You can take any Apple device to any UK Apple Store and we’ll recycle it responsibly and free of charge. You can bring devices of other brands on a like-for-like basis and we’ll recycle them too. We also accept any small electronic device and battery without purchase of a new product or battery.

Most public waste-disposal facilities should also have options for ecological disposal of electronic goods.

Answer 7

If you have access to a pentalobe screwdriver and a small cross head driver (if you changed the screen and battery yourself you may have got these tools in the kit), take the back off, remove the battery (and put it into the battery recycling process if you have anywhere locally that collects old batteries for recycling) and remove the circuit board(s) - really you only need the large one out. If you unclip the leads carefully from the display and touch sensors you can reuse or sell the screen, if you don't care about that then just rip them out or cut them with scissors. If you want it as a display object, put the back back onto it.

Put the circuit board into the microwave (in a paper bag for heat insulation for the plastic tub, inside a lidded plastic tub to protect the microwave from flying debris) and give it a short cook. twenty seconds at full power should be enough. The microwaves will induce arcing in and around the electronics and do it no good at all, damaging the chips. Allow to cool and then crack the components by stamping the board on a rough concrete surface or pound it a bit with a rock. Dispose in electronics waste.

Alternatively, it's a working 'phone. Factory reset it, fill the memory by downloading random games or (as someone else suggested) filming something innocuous, factory wipe it again (repeat if you feel the need) and remove the SIM card. Give it anonymously to some charity that recycles 'phones... it may not fill your needs any more but someone could be glad of it. The risk of your data being retrieved... vanishingly small, the 'phone recycling company don't have resources to recover data off all the 'phones they handle and it'll save the environment more than smashing or trashing it.

Answer 8

Important note: you can still recycle electronics that you have physically destroyed. Recycling facilities generally shred electronics that are not salvageable anyways. You might want to ask people who run your nearest donation bin if they'll accept the unsorted pile of precious metals you're about to give them before proceeding, but if they say yes, then all you'll really need to do is break the phone open, remove the battery (for your own safety), and then break anything that looks important -- namely, any storage that the phone has (other answers have told you where to find the iPhone's storage). Once you have reduced everything to rubble, you can put the rubble bag plus the intact battery into the donation bin.

Answer 9

Josef said in his answer:

Modern devices always encrypt all the data and only delete the key for this encryption if you wipe it. This makes it impossible to restore data after wiping.

This is true for now but a dozen decades from now our current cryptography may be easily breakable through brute force. If you wish for a permanent solution to last the ages, remove the motherboard and grind it. If you don't want to pollute the environment, store the resulting dust inside the case again.

Answer 10

I would follow the advice from other posters regarding wiping the device and SD card if relevant.

If you also wish to physically destroy the device easily without tools the easiest way is to put it on a sheet of paper and drive a vehicle slowly over it back and forwards a few times. I would recommend doing this only with phones which have a removable battery and remove the battery before destroying the phone. Putting it on a sheet of paper means you can easily collect any small bits of plastic etc that break off in the process.

Answer 11

My answer is probably too advanced for your average Joe, and nor what the OP is asking, but in many jurisdictions ‘destroying evidence’ is actually illegal (for obvious reasons,) so while my answer is certainly not the easiest I wanted to share how one can easily enough get away with total data erasure with a much lower chance of getting caught.

Because if a certain three letter agency can round to my house wanting to extract crucial evidence from my phone and I gave them a pile of rubble I think I’d seem slightly suspicious!

Others have discussed the ‘key’ parts that needed to be dealt with, like the NAND flash storage, the SIM, logic board, etc.

So while you could just buy a brand new phone and replace these, the problem is that often these components have physical serial identifiers that professionals would definitely check for.

So you have to keep these parts but render them completely destroyed without being physically smashed into pieces.

Take them out, zap the crap out of them (but not too much!), and put them back in. Piece of cake!

So you the key is electrical damage: 1) quite hard to prove that it was tampered with (but not impossible) if you’re careful and 2) impossible to obtain previous data even with specialised tools like an electron microscope.

Because while overwriting data is mostly reliable, for billions of dollar agencies like the NSA and FBI, sometimes overwriting just isn’t good enough if something important like your life is on the line.

And I acknowledge again that this isn’t as easy to do as taking a sledge hammer to your phone, but I’m sure with the right updated information and right tools, this wouldn’t be too too hard.

And while this is way over the top for what the OP needs, I wanted to write this answer because it is relevant in many cases regarding guaranteed data removal where legal influences might clash with purposely destroying evidence.

Answer 12

Take a metal grinder and grind it to dust. No soldering or dissassembly skills are required.

If you don't want to buy a grinder, then spend several hours rubbing it on a rough concrete until it is completely ground off.

Not even NSA nor CIA nor FBI could recover anything if the dust is fine enough, i.e. no large chunks of chips remain.

These agencies could retrieve some info even if the phone dunked into a hydrofluoric acid or microwaved. Complete incineration (at very hight temp), chemical dissolution (combination of hot nitric and hydrofluoric acids) or mechanical dustification is the only secure way against them.