this post was submitted on 15 May 2024
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cross-posted from: https://sopuli.xyz/post/12670977

iPhone owners say the latest iOS update is resurfacing deleted nudes

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[–] [email protected] 139 points 6 months ago (36 children)

Nothing sinister, we just don't delete what we say we delete. Instead we keep it in your profile to feed the algorithms and set the "deleted" flag to make you think it's gone.

[–] [email protected] 68 points 6 months ago (5 children)

I mean, to be completely fair, that's how data storage works.

We cannot really just make data disappear, so we let it get overwritten instead

[–] [email protected] 23 points 6 months ago (1 children)

But clearly the data is not overwritten and this was intentional. How do I know? Because that would amount to a massive amount of data, if it was de to a bug in Apple software or underlying filesystems, it would be detected in monitoring systems "Hey, we're using 10x the data we should be, maybe we should look into it".

The mistake was in the flag code that was supposed to fool us.

[–] [email protected] 49 points 6 months ago (2 children)

no when I say "overwritten" I mean that the area is set as deleted in the filesystem and the next time something writes to that area the data that was there before is disregarded.

[–] [email protected] 0 points 6 months ago (1 children)

and the next time something writes to that area the data that was there before is disregarded.

A single overwrite might not be enough to defeat physical forensics because shadows of the old data persist in how the new data is stored. Also when it comes to SSDs you might be waiting a long time for the data to get overwritten as the drive will wear-level its erm sectors (what are those things called with SSDs?).

[–] [email protected] 1 points 6 months ago

They are called cells IIRC

[–] [email protected] 13 points 6 months ago (1 children)

the shred command in Linux tries to do this, but it may not work if the hardware moves rewritten data blocks around to mitigate wear.

[–] [email protected] 8 points 6 months ago* (last edited 6 months ago)

shred doesn't even necessarily work at the OS level. If you use something like ext3 and I assume ext4, normally when you overwrite data in a file, you're not overwriting data even at the logical level in the block device. Journalling entails that you commit data to somewhere else on the disk, then update the metadata atomically to reference the new data.

It was more-practical in an era of older filesystems.

[–] [email protected] 11 points 6 months ago* (last edited 6 months ago) (5 children)

Proper deletion should include writing all ones or all zeroes to the block but y'all be lazy as fuck.

[–] [email protected] 29 points 6 months ago* (last edited 6 months ago) (3 children)

Only necessary on the ol spinning rust, with SSDs not only is it completely unnecessary, but it also burns extra writes.

Spinny's store data magnetically on the platter with 1s and 0s, SSDs store data on the NAND as a held charge. If there's a charge in the block it's a 1 if there's no charge it's a 0.

With spinny's, a file gets marked as "deleted" but the residual magnetic 1s and 0s will remain on the platter until eventually overwritten

With SSDs a file gets marked "deleted" and within no more than a few minutes TRIM comes along and ensures the charge on the NAND is released for that data, there's no residuals to worry about like with spinny's and is in fact necessary to ensure decent lifespans.

[–] [email protected] 3 points 6 months ago (1 children)

Wow, the SSD can hold the charges perfectly while unplugged for ages? Amazing.

In a post apocalyptic world where I am in charge of building a storage drive and I’m given all the instructions and fabs, the world is going without storage.

[–] [email protected] 13 points 6 months ago

Wow, the SSD can hold the charges perfectly while unplugged for ages? Amazing.

Yup. Before flash memory, devices like video game cartridges which had game saves actually needed a battery to power the memory holding the saves.

[–] [email protected] 3 points 6 months ago

I want a spinny as a pet now. Sounds cute.

[–] [email protected] 2 points 6 months ago

But wouldn't TRIM be the deleting he is requesting? Removing the charges would be setting all the bits in that block to the same value.

[–] [email protected] 10 points 6 months ago* (last edited 6 months ago) (1 children)

That just makes no sense to do, modern storage is write limited. As long as you used encryption the old bits mean nothing to anyone but you.

[–] [email protected] 3 points 6 months ago

SSDs are. Big storage is not using SSDs.

[–] [email protected] 8 points 6 months ago* (last edited 6 months ago) (1 children)

I’m not an expert, but wouldn’t proper deletion be writing random ones and zeroes to the block? Multiple times?

[–] [email protected] 4 points 6 months ago (2 children)

I don't think it's been shown to make a difference.

[–] [email protected] 4 points 6 months ago

It certainly feels more deleted…

[–] [email protected] 2 points 6 months ago

It was sort of true in the past, but not anymore. I think writing random data once is probably fine, even for most state level actors.

[–] [email protected] 3 points 6 months ago (1 children)

yeah cuz for normal, day-to-day use that's exponentially slower the more you're deleting

You can do that when you wipe something.

[–] [email protected] 0 points 6 months ago

Yeah, such as sensitive photos

[–] [email protected] 2 points 6 months ago

Nitpick: it should be fuzzed with random 0s and 1s.

[–] [email protected] 4 points 6 months ago

That's skipping over the fact that recovering deleted data, even if it isn't overwritten, is not an "oops". It it takes extra effort, and if that data isn't being protected it would be overwritten incidentally as drives are used.

There is a big difference in a database between "flagging" data and actually removing the association of the data to the database.

[–] [email protected] 1 points 6 months ago

The data just needs to be overwritten to be truly deleted.

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