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The Problem with Perceptual Hashes

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Re: The Problem with Perceptual Hashes

#151

Post by J_tt »

a_t48 wrote: post #44
at_a_remove wrote: post #6

I do not know as much about perceptual hashing as I would like, but have considered it for a little project of my own. Still, I know it has been floating around in the wild. I recently came across it on Discord when I attempted to push an ancient image, from the 4chan of old, to a friend, which mysteriously wouldn't send. Saved it as a PNG, no dice. This got me interested. I stripped the EXIF data off of the original…

Adding your friend as a "friend" on discord should disable the filter.

Each user can adjust the settings for how incoming images are filtered, one of the options disables it for friends.

Re: The Problem with Perceptual Hashes

#152

Post by exporectomy »

thaumasiotes wrote: post #148
ezoe wrote: post #110

The problem of hash or NN based matching is, the authority can avoid explaining the mismatch. Suppose the authority want to false-arrest you. They prepare a hash that matches to an innocent image they knew the target has in his Apple product. They hand that hash to the Apple, claiming it's a hash from a child abuse image and demand privacy-invasive searching for the greater good. Then, Apple report you have a file th…

> like the dogs which conveniently bark at police's secret hand sign This isn't necessary; the state of the art is for drug dogs to alert 100% of the time. They're graded on whether they ever miss drugs. It's easy to never miss.

Airport baggage drug dogs must obviously have far fewer false positives than that. So alerting on everything can't be the state of the art.

Re: The Problem with Perceptual Hashes

#153

Post by echelon »

asimpletune wrote: post #105
mrtksn wrote: post #72

The technical challenges aside, I’m very disturbed that my device will be reporting me to the authorities. That’s very different from authorities taking a sneak peek into my stuff. That’s like the theological concept of always being watched. It starts with child pornography but the technology is indifferent towards it, it can be anything. It’s always about the children because we all want to save the children. Soon t…

I have been a big Apple fan ever since my first computer. This is the first time I legitimately thought I need to start thinking about something else. It’s kind of sad.

Good! These assholes have been building a moat around all of computing, and now it's almost impossible to avoid the multi-trillion dollar monster.

Think about all the startups that can't deploy software without being taxed most of our margin, the sign in with apple that prevents us from having a real customer relationship, and the horrible support, libraries, constant changes, etc. It's hostile! It's unfair that the DOJ hasn't done anything about it.

A modern startup cannot succeed without Apple's blessing. To do so would be giving up 50% of the American market. When you're struggling to grow and find traction, you can't do that. It's so wildly unfair that they "own" 50+% of computer users.

Think of all the device owners that don't have the money to pay Apple for new devices or upgrades. They can't repair them themselves. Apple's products are meant to go into the trash and be replaced with new models.

We want to sidestep these shenanigans and use our own devices? Load our own cloud software? We can't! Apple, from the moment Jobs decreed, was fully owned property. No alternative browsers, no scripting or runtimes. No computing outside the lines. You're just renting.

This company is so awful.

Please call your representatives and ask them to break up the biggest and most dangerous monopoly in the world.

Re: The Problem with Perceptual Hashes

#154

Post by techbio »

emodendroket wrote: post #34
rustybolt wrote: post #16

> an Apple employee will then look at your (flagged) pictures. This means that there will be people paid to look at child pornography and probably a lot of private nude pictures as well.

And what do you think the content moderation teams employed by Facebook, YouTube, et al. do all day?

Hopefully, in between the moral sponge work they do, occasionally gaze over a growing history of mugshots, years-left-in-sentence reminders, and death notices for the producers of this content, their enablers, and imitators.

Re: The Problem with Perceptual Hashes

#155

Post by fogof »

ezoe wrote: post #110

The problem of hash or NN based matching is, the authority can avoid explaining the mismatch. Suppose the authority want to false-arrest you. They prepare a hash that matches to an innocent image they knew the target has in his Apple product. They hand that hash to the Apple, claiming it's a hash from a child abuse image and demand privacy-invasive searching for the greater good. Then, Apple report you have a file th…

Well, presumably at that point, someone in that position would just reveal their own files with the hash an prove to the public that they weren't illegal. Sure, it would be shitty to be forced to reveal your private information that way, but you would expose a government agency as fabricating evidence and lying about the contents of the picture in question to falsely accuse someone. It seems like that would be a scandal of Snowden-level proportions.

Re: The Problem with Perceptual Hashes

#156

Post by gpm »

mrtksn wrote: post #72

The technical challenges aside, I’m very disturbed that my device will be reporting me to the authorities. That’s very different from authorities taking a sneak peek into my stuff. That’s like the theological concept of always being watched. It starts with child pornography but the technology is indifferent towards it, it can be anything. It’s always about the children because we all want to save the children. Soon t…

With you up to here, but this is jumping the shark

> I bet you, after the next election in the US your device will be reporting you for spreading far right or deep state lies, depending on who wins.

The US is becoming less stable, sure [1], but there is still a very strong culture of free speech, particularly political speech. I put the odds that your device will be reporting on that within 4 years as approximately 0. The extent that you see any interference with speech today is corporations choosing not to repeat certain speech to the public. Not them even looking to scan collections of files about it, not them reporting it to the government, and the government certainly wouldn't be interested if they tried.

The odds that it's reporting other crimes than child porn though, say, copyright infringement. That strikes me as not-so-low.

[1] I agree with this so much that it's part of why I just quit a job that would have required me to move to the US.

Re: The Problem with Perceptual Hashes

#157

Post by gpm »

fogof wrote: post #155
ezoe wrote: post #110

The problem of hash or NN based matching is, the authority can avoid explaining the mismatch. Suppose the authority want to false-arrest you. They prepare a hash that matches to an innocent image they knew the target has in his Apple product. They hand that hash to the Apple, claiming it's a hash from a child abuse image and demand privacy-invasive searching for the greater good. Then, Apple report you have a file th…

Well, presumably at that point, someone in that position would just reveal their own files with the hash an prove to the public that they weren't illegal. Sure, it would be shitty to be forced to reveal your private information that way, but you would expose a government agency as fabricating evidence and lying about the contents of the picture in question to falsely accuse someone. It seems like that would be a scan…

It wouldn't prove anything, because hash functions are many-to-one. It's entirely possible that it was just a coincidence.

Re: The Problem with Perceptual Hashes

#158

Post by tialaramex »

xuki wrote: post #117
Klonoar wrote: post #114

Earlier quoted context omitted.

I would really like people to start answering this: what exactly do you think has changed? e.g, >That’s very different from authorities taking a sneak peek into my stuff. To be very blunt: - The opt out of this is to not use iCloud Photos. - If you _currently_ use iCloud Photos, your photos are _already_ hash compared. - Thus the existing opt out is to... not use iCloud Photos. The exact same outcome can happen regar…

It makes even less sense, given that they are currently doing this with your iCloud photos. Now they have this tool that can match to a database of photos, how do we know they wouldn't use this to identify non-sexual photos? Maybe Tim Cook wouldn't, what about the next CEO? And the one after that?

What makes you think that Apple has a database of actual child sex abuse images? Does that feel like a thing you'd be OK with? "Oh, this is Jim, he's the guy who keeps our archive of sex abuse photographs here at One Infinite Loop" ? If you feel OK with that at Apple, how about at Facebook? Tencent? What about the new ten-person SV start-up would-be Facebook killer whose main founder had a felony conviction in 1996 for violating the Mann Act. Still comfortable?

Far more likely Apple takes a bunch of hashes from a third party in the law enforcement side of things (ie cops) and trust that the third party is definitely giving them hashes to protect against the Very Bad Thing that Apple's customers are worried about.

Whereupon what you're actually trusting isn't Tim Cook, it's a cop. I'm told there are good cops. Maybe all this is done exclusively by good cops. For now.

Now, I don't know about the USA, but around here we don't let cops just snoop about in our stuff, on the off-chance that by doing so they might find kiddie porn. So it should be striking that apparently Apple expects you to be OK with that.

Re: The Problem with Perceptual Hashes

#159

Post by hda2 »

remram wrote: post #133
marcinzm wrote: post #27

Given all the zero day exploits on iOS I wonder if it's now going to be viable to hack someone's phone and upload child porn to their account. Apple with happily flag the photos and then, likely, get those people arrested. Now they have to, in practice, prove they were hacked which might be impossible. Will either ruin their reputation or put them in jail for a long time. Given past witch hunts it could be decades be…

The "hack" might be very simple, since I'm sure it's possible to craft images that look like harmless memes but trigger the detection for CP.

The new and improved swatting.

Re: The Problem with Perceptual Hashes

#160

Post by efitz »

gpm wrote: post #156
mrtksn wrote: post #72

The technical challenges aside, I’m very disturbed that my device will be reporting me to the authorities. That’s very different from authorities taking a sneak peek into my stuff. That’s like the theological concept of always being watched. It starts with child pornography but the technology is indifferent towards it, it can be anything. It’s always about the children because we all want to save the children. Soon t…

With you up to here, but this is jumping the shark > I bet you, after the next election in the US your device will be reporting you for spreading far right or deep state lies, depending on who wins. The US is becoming less stable, sure [1], but there is still a very strong culture of free speech, particularly political speech. I put the odds that your device will be reporting on that within 4 years as approximately 0…

Apple has a shitty record wrt free speech. Apple hates free speech. Apple likes “curation”. They canned Parler in a heartbeat; they also police the App Store for anything naughty.
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