73

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.

  • 3
    Don't know if this works or not, just a guess: (1) Factory reset, (2) Leave phone in a bucket of water for a month or two. (3) Electronics recycling. Assuming phone is not water proof obviously. – Anders Jun 25 at 8:00
  • 27
    @Anders the bucket of water would create a bit of a toxic soup that would be difficult to dispose of – schroeder Jun 25 at 8:04
  • 37
    Who is your expected opponent? Every security question needs to address what kind of threat level is expected. If you're just an average person, without being the leader (or important key person) of a significant economic or political power base, then a factory reset should be enough. Otherwise, if your opponent is the secret service of a whole country and is willing to spend billions in cracking it, then it's unlikely you'll get a satisfying answer here. And if you are a high-value target, you might have already been compromised the moment you bought the (specifically prepared) phone. – vsz Jun 26 at 14:25
  • 4
    sell it to a pirate market in tijuana when you're done with it then it'll change hands enough times to mask your activity – Dmitri DB Jun 26 at 18:13
  • 5
    I'm just astounded that you don't have a hammer. I don't think I've ever run into someone that didn't have a hammer before! They work really well for so many tasks and can be had for so cheap (well, unless you are the US military...). – Brian Knoblauch Jun 27 at 12:20

11 Answers 11

72

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.

  • 5
    It's not cheap to recover data after overwriting the entire storage with something else... – ThoriumBR Jun 25 at 21:20
  • 11
    @AlmaDo: If data has been overwritten, it certainly cannot be restored for $70. Standard quotes by recovery companies start at $500-$1000, but with the caveat that a) it can get much more expensive, and b) overwritten data is generally unrecoverable. So realistically you are looking at at least a 5-figure sum for maybe recovering something. – sleske Jun 26 at 8:35
  • 9
    Wouldn't putting locks on the garbage cans encourage people to look into it? Now I'm curious about your locked garbage too! – Nelson Jun 26 at 9:05
  • 8
    @Nelson Locked garbage cans are not that uncommon. It prevents people from dumping their trash in your can, which is mainly a problem if you pay per time they empty it (which is common here). – Mast Jun 26 at 9:52
  • 11
    "point the camera out of the window" or at the wall, ground, put it in a shoebox, as long as nothing sensitive is being recorded. Otherwise you'd have simply traded problems :-) – Mast Jun 26 at 9:53
49

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.

  • Comments are not for extended discussion; this conversation has been moved to chat. – Rory Alsop Jun 26 at 13:31
  • 12
    Impossible for now, but possibly breakable in little time a few decades from now. So, if you really wish to hide your stuff forever, go for hardware destruction. – Renan Jun 26 at 20:09
  • 9
    @Renan What makes you believe the encryption will suddenly be easily breakable in only a few decades? Unless you think quantum computers are suddenly going to be extremely powerful, (itself unlikely), you'd then have to assume a huge break in the math, which is also unlikely. Increases in computing power, even at Moores law speed (which itself won't continue forever) won't break 128 bit key sizes. – Steve Sether Jun 26 at 20:24
  • @SteveSether by napkin calculation, 140 years from now 128-bit encryption will be bruteforceable in 3 days - supposing no paradigm shift. With optimistic paradigm shifts with quantum computer 128-bit encryption would be bruteforceable in 3 days at around 35 years from now. – Renan Jun 26 at 20:42
  • 9
    @Renan Moores law is unlikely to continue for another 140 years. We're at the level of dozens of atoms now, and you can't shrink smaller than 1 atom. Predicting an advance in quantum computing isn't feasible beyond "it's not going to happen anytime soon". – Steve Sether Jun 26 at 20:57
16

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.

  • 2
    How do I "open the phone"? What does "unseat the chips" mean? Sorry, I'm not very good with these things. Also, yes, I do not trade state secrets or any data that is remotely related to any government. – Alma Do Jun 25 at 7:50
  • @AlmaDo There are many tutorials videos out there on how to open a phone. "Unseat" means break the chips out of their position. With today's small components this might be a bit tricky, but with a sharp screwdriver you will certainly do. – Marcel Jun 25 at 10:22
  • 2
    As an alternative to prying the chips up, you can use two pairs of vice grips clamped to opposite ends to snap the chip in half. This has the advantage of not having to worry about the screw driver you're prying with slipping loose and gouging the work surface. – Dan Neely Jun 25 at 22:50
  • 8
    If you're going to the trouble of opening the phone, you're better off just destroying the NAND chip as far as possible. ifixit will have photos of its location on the board. Popping off every chip and disposing of them separately isn't going to help much: it doesn't matter where the SoC, modem, etc., end up, it's the NAND that's going to contain your data (though, a modern phone may encrypt the data and store the keys on a different chip). – Bob Jun 26 at 1:56
  • 1
    If you are going to destroy the NAND chips, a factory reset is superfluous. It's like erasing pencil written text on a paper and burn the paper afterwards. – ThoriumBR Jun 27 at 14:00
10

"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!

  • Do I need to do some special procedure to remove the SD card? (I assume that card is something like an HDD for a PC but I might be wrong). – Alma Do Jun 25 at 8:39
  • @AlmaDo SD cards are exchangeable - modern Android phones usually have a slot on the side of the device, which you can open with a small pin (please nothing thicker than a paper clip). Apple iPhones still don't have SD card slots. – Martin Fürholz Jun 25 at 8:43
  • 1
    I have an iPhone. Does it mean I don't have to remove SD (since it doesn't have one?) – Alma Do Jun 25 at 8:46
  • @AlmaDo yes exactly – Martin Fürholz Jun 25 at 8:46
8

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.

  • 1
    I find the Apple link contradictory to what you are saying. There are additional steps mentioned but none of them refers to the storage inside the iPhone, these are things related to cloud, cellphone network, and other devices. – Melebius Jun 26 at 8:06
  • Well, if the device was functioning properly then I'd just keep it to myself, I'm only thinking to replace it because I already had to replace parts of it several times (screen, battery etc) and it's getting worse + old iOS means no apps can be updated anymore, hence security risks etc. – Alma Do Jun 26 at 8:33
  • 1
    The androidpit article is a bit strange. Although it says "2 weeks ago" as the article publication time(?), the comments are going back to 2015 and the cited sources are from 2014 and concern only unencrypted devices. As discussed in the answer by @Josef, encrypted Android devices should not be problematic to factory reset. – Dubu Jun 26 at 13:02
  • @Dubu might be the time since last edit. – Tvde1 Jun 26 at 13:51
  • Well yes, if it was my phone and it still worked I'd likely keep it as a backup.. – George M Reinstate Monica Jun 26 at 22:45
4

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.

1

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.

  • 7
    Putting a circuit board in the microwave is a really bad idea. The arcing could damage the microwave, release toxic fumes, or even potentially catch fire, which would then catch the paper bag and plastic tub on fire, making it even more dangerous. If you don't believe me check out this video of a circuit board being microwaved (youtube.com/watch?v=LH71kcrSYYU). Yes, the video uses a much larger board, but the dangers are still applicable – Kevin Wells Jun 26 at 17:20
0

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.

-1

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.

  • 2
    "a dozen decades from now" - I'm not sure if the OP, or anyone, would care if the data is recoverable 120 years from now. The rest of the answer is a copy of George's answer below and suffers the same problem (requires work tool). – schroeder Jun 27 at 6:46
-2

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.

  • 1
    Envelope could also do instead of the paper, that way you don't have glass shards on your tires. (may not puncture them but they can fling off the tires when you start driving and damage the paint on the car) – Alexandre Aubrey Jun 26 at 3:12
  • 2
    Since the OP has added that this is a iPhone 5, and therefore doesn't have a removable battery this is not relevant advice since as you pointed out crushing a battery could be quite dangerous – Kevin Wells Jun 26 at 17:12
-4

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.

  • 11
    Someone who doesn't even have a hammer might not have ready access to a grinder... ...and I have the impression that the mess in the flat might be unacceptable. – Toby Speight Jun 25 at 16:53
  • 6
    "I don't have to do it with work tools " is a requirement – schroeder Jun 25 at 16:54
  • 4
    OP specifically said no destructive tools like a hammer, and no pollution. – Ghedipunk Jun 25 at 16:54
  • 4
    While yes, grinding something to dust would make it impossible to get the data off of it, security works within constraints of usability. One way to secure a hard drive is to disconnect it from all computers, encase it in several feet of cement, and bury it in an undisclosed location. That defeats the purpose, though. Security requires mitigating risk, within limits that the users are willing to put up with. If OP isn't willing to take a hammer to their device, and doesn't want to pollute, they're definitely not going to use a grinder, so this advice won't be followed, thus is anti-security. – Ghedipunk Jun 25 at 17:00
  • 16
    Bonus - the toxic powder in your lungs will destory all your information – Milney Jun 25 at 17:46

protected by schroeder Jun 27 at 6:41

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.