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What's the safest known way to make my smartphone data irrecoverable? It's a Galaxy S5 and a Galaxy S8+. For a normal hard-drive I'd just use dd or dban to nuke it. What's the equivalent for a smartphone? I believe it uses flash memory or something like this...

Ah, I forgot to mention but I'm talking about the internal storage.

>>7408 Smashing it. (Especially the NAND on the board) Microwaving it. Burning it. Or less destructive, dd /dev/zero from a custom recovery of sorts. But I haven't tried, but I remeber TWRP offering a basic busybox shell in the recovery. Else you can always download one of the generic 'empty space wipers' which most of the time don't even require root since they just make huge files filled with gibberish (or zeroes) and wipes all the 'marked for overwrite' deleted files. Also, why use a S8+ for usage involving data that REALLY needs to be cleaned?

>>7410 Thanks for the help. >Also, why use a S8+ for usage involving data that REALLY needs to be cleaned? I didn't, anon. Actually, it's not really that sensitive, I just want to try to erase it in a way someone couldn't find so easily just to be sure... Maybe the empty space wipers you mentioned are what I'm looking for.

i use 'secure eraser' from f-droid to periodically wipe free space. however, there is no way to be absolutely certain that 100% of data on flash memory has been completely wiped, even with dd. at any rate, you can get to the vast majority of it. the alternative would be to grind the physical memory to fine powder. dd, etc, are only 100% effective on standard hdd's, not ssd's, usbsticks, phones, etc.

>>7412 Is this safe for the phone? I bought my phone just a while ago so I didn't want to take risks. I believe I'll give this one a try.

>>7412 I couldn't find it on F-Droid. Would you mind linking it, anon?

smash it, mix powdered rust and aluminum powder in a bowl with phone chunks, light on fire, success?

>>7414 oh, sorry, i got 'secure eraser' on xda labs, not f-droid.

>>7408 >For a normal hard-drive I'd just use dd or dban to nuke it. What's the equivalent for a smartphone? I believe it uses flash memory or something like this... First of all you should have encrypted private information from the beginning. But that doesn't help you now. There is no (legitimate) equivalent to dban for a smartphone because like you said it uses flash memory. Flash firmware uses wear leveling which means software can't control where the writes go physically or what is being overwritten. The other issue is that flash chips are normally built with higher capacity than is shown to the user. When flash cells get worn out they are hidden and some of the extra ones replace it. That can also leave you with undeletable data. As any "data erasure" apps for smartphones are a scam. >What's the safest known way to make my smartphone data irrecoverable? As others said, physical destruction is always the safest. If you want a more nuanced answer then you need to describe a threat model.

>>7417 Thank you. But why encrypting beforehand works? If I format it, the undeletable data will still encrypted in this case so even if someone find it, it'll be encrypted so it's useless? That's the point? But if that's the case, for example, if I have stuff I want to hide now, encrypting it now and then formatting won't do the same as if I had encrypted before? >"data erasure" apps for smartphones are a scam Well, there's no possible way to at least make it a little bit more difficult to be recovered? Let's say if I have a phone with private data I deleted just formatting it, wouldn't using an app to "wipe free space" with random data make it a little bit more difficult to recover everything? If they could recover 100 files, at least reduces it to 70 files. Or it's 100% scam and changes absolutely nothing?

>>7420 >encrypted data is useless No, it can and will be decrypted, it might just take a very long time.

>>7421 What do you mean by "very long time"? I'm not doing anything wrong anyway, I don't think they'd waste all this time.

>>7421 just like it will merely take a very long time for the earth to fall into the sun.

>>7425 even if we ignore a possibility of a backdoor, depending on how interesting OP is, if they made big enough enemies, it wouldn't take that long... >>7423 then why do you care about deleting your data?

>>7427 The biggest reason is I want to sell my phone and feel uncomfortable in selling it without doing at least what I can to avoid stuff being recovered. Sensitive pictures of someone else, mostly.

>>7429 >>7423 >>I don't think they'd waste all this time. i don't understand why this isn't an option then

>>7429 Generally, encrypting then factory resetting is the way to go. For photos, always store them on an SD card instead of in the system (you dont have an apple phone right lain?). It is pretty hard for most people buying your phone to do forensic recovery if you encrypt then delete, then factory reset, and then flash a new phone OS onto the device. you are stressing over the .001% chance that a 3 letter will get a hold of it and hypothetically break the encryption with a quantum supercomputer meme or something along those lines. Most people just want the phone to listen to spotify, browse tinder and snapchat/facebook with people, not actually stealing your information.

>>7427 >it wouldn't take that long... assuming it's not compromised(which seems likely), it would take billions of years to crack AES-128 even if they could try 10^20 (one hundred quintillion) keys per second, which is a high estimate for what even the NSA can do. Even with quantum computers, while AES-128 would be broken, AES-256 would have that same level of hardness.

https://www.bleachbit.org/download :P

>>7439 How this would help him? It's not for PC?

Flash memory won't be erased with traditional gnu tools designed for spinning platters and their predictable layout. The only secure way is to either have information encrypted from start or physically destroy the memory banks.

>>7454 Correct me if I am wrong, but if you overwrite the entire flash-mem at once start to finish, wouldn't that be effective? In my research into securely deleting files off SSD that was what I learned, completely wiping the drive would work

>>7457 >if you overwrite the entire flash-mem at once start to finish, wouldn't that be effective? No because an 8gb flash drive doesn't have 8gb of flash cells it has more. The firmware silently swaps out worn cells behind your back so data can still persist. Whether your threat model includes an adversary who can recover it is a different question.