The Problem with Perceptual Hashes • Hacker News Board

Re: The Problem with Perceptual Hashes

#321

Post by wingspar » Sat, Aug 07, 2021, 2:04 PM UTC

tjoff wrote: post #311

marcellus23 wrote: post #301

Earlier quoted context omitted.

No, like many others commenting on the issue, you seem to only have a vague idea of how it works. Only photos being uploaded to iCloud are being scanned for CSAM.

Then tell us. Because this is what apple says: The Messages app will use on-device machine learning to warn about sensitive content, while keeping private communications unreadable by Apple. Next, iOS and iPadOS will use new applications of cryptography to help limit the spread of CSAM online, while designing for user privacy. https://www.apple.com/child-safety/ There is no ambiguity here. Of course they will scan im…

The operative separator is “Next”

Apple is announcing 3 new ‘features’.

First one scans iMessage messages / photos on device / warns kids and partners.

Second one is the CSAM photo hash compare in iCloud upload feature.

Third one is the Siri search protection/warning feature.

Re: The Problem with Perceptual Hashes

#322

Post by gambiting » Sat, Aug 07, 2021, 2:07 PM UTC

zimpenfish wrote: post #251

gambiting wrote: post #68

Earlier quoted context omitted.

>>I have a tough time believing that false positives would slip through that many layers. I don't, not in the slightest. Back in the days when Geek Squad had to report any suspicious images found during routine computer repairs, a guy got reported to the police for having child porn, arrested, fired from his job, named in the local newspaper as a pedophile, all before the prosecutor was actually persuaded by the defe…

> Back in the days when Geek Squad had to report any suspicious images [...] which turned out to be his own grand children Do you have a link to sources for this case? I've had a look and can't see anything that matches right now.

So you know, I'm genuienly trying to find you a link for this case, but it just proves how absolutely shit Google is nowadays. I swear just few years ago I'd find it by just searching "geek squad grandfather wrongly accused" - now searching for this phrase gives me absolute nonsense, with anything past result 5-6 being completely and totally unrelated(6th result is wiki page for killing of marther Luther king).

I will post a link if I can't find it, but dealing with Google nowadays is beyond frustrating.

Re: The Problem with Perceptual Hashes

#323

Post by gpm » Sat, Aug 07, 2021, 2:08 PM UTC

l33t2328 wrote: post #297

gpm wrote: post #156

Earlier quoted context omitted.

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…

I don’t see how the US is becoming “less stable” in any meaningful sense. Can you elaborate?

Both sides of the political spectrum think the other side is stupid, and evil. The gap between the two sides is getting bigger. Politicians and people (especially on the right, but to some extent on the left) are increasingly willing to cheat to remain in power.

If you want some concrete examples:

- Trump's attempted coup, the range of support it received, the lack of condemnation it received.

- Law's allowing things like running over protestors

- Law's with the transparent goal of suppressing voters

- Widespread support (not unjustified IMO) for stacking the supreme court

- Police refusing to enforce certain laws as a political stance (not because they legitimately think they're unlawful, just that they don't like them)

- (Justified) lack of trust in the police quickly trending higher

- (Justified?) lack of trust in the military to responsibly use tools you give it, and support for a functional military

- (Justified?) lack of faith in the border guards and the ability to pass reasonable immigration laws, to the point where many people are instead advocating for just not controlling the southern border.

Generally these (and more) all speak towards the institutions that make the US a functional country failing. The institutions that make the rules for the country are losing credibility, the forces that enforce the rules are losing credibility. Neither of those are things that a country can survive forever.

Re: The Problem with Perceptual Hashes

#324

Post by bccdee » Sat, Aug 07, 2021, 2:17 PM UTC

t0mas88 wrote: post #270

new_realist wrote: post #52

Earlier quoted context omitted.

This is already possible using other services (Google Drive, gmail, Instagram, etc.) that already scan for CP.

Does Google scan all files you upload to them with an algorithm like the one now proposed? Or do they have only a list of exact (not perceptual) SHA hashes of files to flag on? The latter I think is also used for pirated movies etc being removed under DMCA?

I'm pretty sure they use perceptual hashes for matching CSAM. A lot of cloud services do this sort of thing.

Re: The Problem with Perceptual Hashes

#325

Post by [deleted] » Sat, Aug 07, 2021, 2:18 PM UTC

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…

[deleted]

Re: The Problem with Perceptual Hashes

#326

Post by jeromegv » Sat, Aug 07, 2021, 2:19 PM UTC

tjoff wrote: post #311

marcellus23 wrote: post #301

Earlier quoted context omitted.

No, like many others commenting on the issue, you seem to only have a vague idea of how it works. Only photos being uploaded to iCloud are being scanned for CSAM.

Then tell us. Because this is what apple says: The Messages app will use on-device machine learning to warn about sensitive content, while keeping private communications unreadable by Apple. Next, iOS and iPadOS will use new applications of cryptography to help limit the spread of CSAM online, while designing for user privacy. https://www.apple.com/child-safety/ There is no ambiguity here. Of course they will scan im…

You are mistaken, the iMessage feature is for parental consent and is not used at all for the CSAM database.

It is not related to the CSAM database feature.

Read details here: https://daringfireball.net/2021/08/apple_child_safety_initia...

Re: The Problem with Perceptual Hashes

#327

Post by jeromegv » Sat, Aug 07, 2021, 2:20 PM UTC

voakbasda wrote: post #308

marcellus23 wrote: post #301

Earlier quoted context omitted.

No, like many others commenting on the issue, you seem to only have a vague idea of how it works. Only photos being uploaded to iCloud are being scanned for CSAM.

And you have an overly optimistic idea that they will not enable this feature more broadly. You really want to trust them, when this incident shows that they do not intend to be fully forthright with such changes?

They published full technical documents of what is happening and what is changing, and this is what this debate is about. It's a bit odd to argue that they are not forthright, this is all documented. They could have updated their terms of service vaguely and never mention that feature, they did not.

Re: The Problem with Perceptual Hashes

#328

Post by CRConrad » Sat, Aug 07, 2021, 2:23 PM UTC

sharken wrote: post #255

BiteCode_dev wrote: post #217

Earlier quoted context omitted.

Na they will ruin your life even if you are found innocent and pay no price for it. That's the problem: the terrible asymetry. The same one you find with TOS, or politicians working for lobbists.

Who would a company hire: the candidate with a trial for CP due to a false positive or the candidate without ? And this is just to address the original concept of this scanning. As many others have pointed out there is too much evidence pointing to other uses in the future.

> Who would a company hire: the candidate with a trial for CP due to a false positive or the candidate without ?

First time I've seen it abbreviated like that; took me a while to grasp. Well, more of a plausible "Enemy of society" than what I came up with: https://news.ycombinator.com/item?id=28060995

Re: The Problem with Perceptual Hashes

#329

Post by tjoff » Sat, Aug 07, 2021, 2:23 PM UTC

wingspar wrote: post #321

tjoff wrote: post #311

Earlier quoted context omitted.

Then tell us. Because this is what apple says: The Messages app will use on-device machine learning to warn about sensitive content, while keeping private communications unreadable by Apple. Next, iOS and iPadOS will use new applications of cryptography to help limit the spread of CSAM online, while designing for user privacy. https://www.apple.com/child-safety/ There is no ambiguity here. Of course they will scan im…

The operative separator is “Next” Apple is announcing 3 new ‘features’. First one scans iMessage messages / photos on device / warns kids and partners. Second one is the CSAM photo hash compare in iCloud upload feature. Third one is the Siri search protection/warning feature.

Stand corrected on the first part.

But surely iCloud upload feature is on the device. And if it was only in the cloud they wouldn't need to mention iOS or iPadOS at all.

Re: The Problem with Perceptual Hashes

#330

Post by jeromegv » Sat, Aug 07, 2021, 2:23 PM UTC

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.

Genuinely curious, why? This scanning was already happening server-side in your iCloud photos, just like Google Photos, etc. Now they are removing it from server-side to client-side (which still require this photo to be hosted in iCloud)

What changed, really?