[HN Gopher] The Problem with Perceptual Hashes
       ___________________________________________________________________
        
       The Problem with Perceptual Hashes
        
       Author : rivo
       Score  : 644 points
       Date   : 2021-08-06 19:29 UTC (1 days ago)
        
 (HTM) web link (rentafounder.com)
 (TXT) w3m dump (rentafounder.com)
        
       | read_if_gay_ wrote:
       | Big tech has been disintegrating the foundational principles on
       | which our society is built in the name of our society. Every one
       | of their moves is a deeper attack on personal freedom than the
       | last. They need to be dealt with. Stop using their services,
       | buying their products, defending them when they silence people.
        
       | lliamander wrote:
       | What about genuine duplicate photos? Say there is a stock picture
       | of a landscape, and someone else goes and takes their own picture
       | of the same landscape?
        
       | stickfigure wrote:
       | I've also implemented perceptual hashing algorithms for use in
       | the real world. Article is correct, there really is no way to
       | eliminate false positives while still catching minor changes
       | (say, resizing, cropping, or watermarking).
       | 
       | I'm sure I'm not the only person with naked pictures of my wife.
       | Do you really want a false positive to result in your intimate
       | moments getting shared around some outsourced boiler room for
       | laughs?
        
         | jjtheblunt wrote:
         | Why would other people have a naked picture of your wife?
        
           | giantrobot wrote:
           | She's a comely lass. I can't recommend her pictures enough.
        
           | pdpi wrote:
           | GP's wife presumably had a personal life before being in a
           | relationship with GP. It's just as reasonable that her prior
           | partners have her photos as it is for GP to have them.
        
           | dwaltrip wrote:
           | Others have pictures of _their_ wife, not GP 's wife.
        
           | jjtheblunt wrote:
           | (joke)
        
         | planb wrote:
         | I fully agree with you. But while scrolling to next comment, a
         | question came to my mind: Would it really bother me if some
         | person that does not known my name, has never met me in real
         | life and never will is looking at my pictures without me ever
         | knowing about it? To be honest, I'm not sure if I'd care.
         | Because for all I know, that might be happening right now...
        
         | zxcvbn4038 wrote:
         | Rookie mistake.
         | 
         | Three rules to live by:
         | 
         | 1) Always pay your taxes
         | 
         | 2) Don't talk to the police
         | 
         | 3) Don't take photographs with your clothes off
        
           | slapfrog wrote:
           | > _2) Don't talk to the police_
           | 
           | 2b) Don't buy phones that talk to the police.
        
           | jimmygrapes wrote:
           | I might amend #2 a bit to read "Be friends with the police"
           | as that has historically been more beneficial to those who
           | are.
        
             | mattnewton wrote:
             | Lots of people have believed that they were friends with
             | the police and were actually being manipulated into
             | metaphorically hanging themselves- some of them innocent.
             | 
             | Counterargument, why you should not talk to the police (In
             | the US): https://youtu.be/d-7o9xYp7eE
        
             | digi59404 wrote:
             | The point that being friends with police will be beneficial
             | to you - Means there's a scenario where the inverse is also
             | true. Not being friends with police is used to your
             | detriment.
             | 
             | Police Officers exist in a career field that is riddled
             | with incidents of Tunnel Vision. The sibling comment posts
             | a video about not talking to police from a law professor.
             | I'd heed that advice.
        
               | l33t2328 wrote:
               | That law professor clearly never talked his way out of a
               | speeding ticket.
        
         | vineyardmike wrote:
         | > Do you really want a false positive to result in your
         | intimate moments getting shared around some outsourced boiler
         | room for laughs?
         | 
         | these people also have no incentive to find you innocent for
         | innocent photos. If they err on the side of false-negative,
         | they might find themselves at the wrong end of a criminal
         | search ("why didn't you catch this"), but if they false-
         | positive they at worse ruin a random person's life.
        
           | whakim wrote:
           | This is mostly orthogonal to the author's original point
           | (with which I concur, having also implemented image
           | similarity via hashing and hamming distance). There just
           | aren't a lot of knobs to tune using these algorithms so it's
           | difficult if not impossible to make small changes to err on
           | the side of reducing false positives.
        
           | TchoBeer wrote:
           | Does claiming a false positive not run the risk of libel?
        
             | vineyardmike wrote:
             | IANAL but i doubt it - they just forward to law enforcement
        
               | TchoBeer wrote:
               | Is making false claims to law enforcement not illegal?
        
               | lazide wrote:
               | Only if you know they are false at the time.
        
             | heavyset_go wrote:
             | I doubt it. The claim isn't being published and you'd have
             | a hard time proving damages.
        
           | jdavis703 wrote:
           | Even still this has to go to the FBI or other law enforcement
           | agency, then it's passed on to a prosecutor and finally a
           | jury will evaluate. I have a tough time believing that false
           | positives would slip through that many layers.
           | 
           | That isn't to say CASM scanning or any other type of drag net
           | is OK. But I'm not concerned about a perceptual hash ruining
           | someone's life, just like I'm not concerned about a botched
           | millimeter wave scan ruining someone's life for weapons
           | possession.
        
             | mattnewton wrote:
             | By the time it has reached a jury you're already publicly
             | accused of having CSAM which is a life ruining moment on
             | its own, and no one before the jury has much incentive to
             | halt the process on your behalf.
        
             | vineyardmike wrote:
             | > But I'm not concerned about a perceptual hash ruining
             | someone's life
             | 
             | I want ZERO computerized algorithms involved in any law
             | enforcement process - especially the "criminal hunting"
             | steps.
        
             | gambiting wrote:
             | >>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 defense attorney
             | to look at these "disgusting pictures".....which turned out
             | to be his own grand children in a pool. Of course he was
             | immediately released but not before the damage to his life
             | was done.
             | 
             | >>But I'm not concerned about a perceptual hash ruining
             | someone's life
             | 
             | I'm incredibly concerned about this, I don't see how you
             | can not be.
        
               | zimpenfish wrote:
               | > 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.
        
               | gambiting wrote:
               | 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.
        
         | zimpenfish wrote:
         | > Do you really want a false positive to result in your
         | intimate moments getting shared around some outsourced boiler
         | room for laughs?
         | 
         | You'd have to have several positive matches against the
         | specific hashes of CSAM from NCMEC before they'd be flagged up
         | for human review, right? Which presumably lowers the threshold
         | of accidental false positives quite a bit?
        
         | mjlee wrote:
         | > I'm sure I'm not the only person with naked pictures of my
         | wife.
         | 
         | I'm not completely convinced that says what you want it to.
        
           | dwaltrip wrote:
           | The reasonable interpretation is that GP is saying many
           | people may have private pictures of their partner.
        
           | enedil wrote:
           | Didn't she possibly have previous partners?
        
             | iratewizard wrote:
             | I don't even have nude photos of my wife. The only person
             | who might would be the NSA contractor assigned to watch
             | her.
        
               | x-shadowban wrote:
               | what function does the word "even" perform in this
               | sentence?
        
               | iratewizard wrote:
               | It's used to emphasize the concept that if anyone would
               | have nudes of my wife, it would be me, her husband.
               | Here's another example of "even" used as an emphasizing
               | word.
               | 
               | >I don't know how to answer that.
               | 
               | >Even I don't know how to answer that.
               | 
               | Hope that helps you with your ESL tests!
        
               | jefftk wrote:
               | The parallel to the construction you used before would be
               | "I don't even know how to answer that" which means
               | something quite different from "Even I don't know how to
               | answer that".
        
               | ksenzee wrote:
               | I believe it's meant to be "Even _I_ don't have..."
        
             | websites2023 wrote:
             | Presumably she wasn't his wife then. But also people have
             | various arrangements so I'm not here to shame.
        
         | avnigo wrote:
         | I would want absolute transparency as to which of my photos
         | have been exposed to the human review process and found to be
         | false positives.
         | 
         | Somehow I doubt we would ever get such transparency, even
         | though it would be the right thing to do in such a situation.
        
         | nine_k wrote:
         | Buy a subcompact camera. Never upload such photos to any cloud.
         | Use your local NAS / external disk / your Linux laptop's
         | encrypted hard drive.
         | 
         | Unless you prefer to live dangerously, of course.
        
           | ohazi wrote:
           | Consumer NAS boxes like the ones from Synology or QNAP have
           | "we update your box at our whim" cloud software running on
           | them and are effectively subject to the same risks, even if
           | you try to turn off all of the cloud options. I probably
           | wouldn't include a NAS on this list unless you built it
           | yourself.
           | 
           | It looks like you've updated your comment to clarify _Linux_
           | laptop 's encrypted hard drive, and I agree with your line of
           | thinking. Modern Windows and Mac OS are effectively cloud
           | operating systems where more or less anything can be pushed
           | at you at any time.
        
             | moogly wrote:
             | Synology [...] have "we update your box at our whim"
             | 
             | You can turn off auto-updates on the Synology devices I own
             | at least (1815+, 1817+).
        
             | derefr wrote:
             | With Synology's DSM, at least, there's no "firmware" per
             | se; it's just a regular Linux install that you have sudo(1)
             | privileges on, so you can just SSH in and modify the OS as
             | you please (e.g. removing/disabling the update service.)
        
             | cm2187 wrote:
             | At least you can deny the NAS access to the WAN by blocking
             | it on the router or not configuring the right gateway.
        
         | 7373737373 wrote:
         | I, too, have worked on similar detection technology using state
         | of the art neural networks. There is no way there won't be
         | false positives, I suspect many, many more than true positives.
         | 
         | It is very likely that as a result of this, thousands of
         | innocent people will have their most private of images viewed
         | by unaccountable strangers, will be wrongly suspected or even
         | tried and sentenced. This includes children, teenagers,
         | transsexuals, parents and other groups this is allegedly
         | supposed to protect.
         | 
         | The willful ignorance and even pride by the politicians and
         | managers who directed and voted for these measures to be taken
         | disgusts me to the core. They have no idea what they are doing
         | and if they do they are simply plain evil.
         | 
         | It's a (in my mind entirely unconstitutional) slippery slope
         | that can lead to further telecommunications privacy and human
         | rights abuses and limits freedom of expression by its chilling
         | effect.
         | 
         | Devices should exclusively act in the interest of their owners.
        
           | nonbirithm wrote:
           | Microsoft, Facebook, Google and Apple have scanned data
           | stored on their servers for CSAM for over a decade already.
           | The difference is that Apple is moving the scan on-device.
           | Has there been any report of even a single person who's been
           | a victim of a PhotoDNA false positive in those ten years? I'm
           | not trying to wave away the concerns about on-device privacy,
           | but I'd want evidence that a such significant scale of
           | wrongful conviction is plausible as a result of Apple's
           | change.
           | 
           | I can believe that a couple of false positives would
           | inevitably occur assuming Apple has good intentions (which is
           | not a given), but I'm not seeing how _thousands_ could be
           | wrongfully prosecuted unless Apple weren 't using the system
           | like they state they will. At least in the US, I'm not seeing
           | how a conviction can be made on the basis of a perceptual
           | hash alone without the actual CSAM. The courts would still
           | need the actual evidence to prosecute people. Getting people
           | arrested on a doctored meme that causes a hash collision
           | would at most waste the court's time, and it would only
           | damage the credibility of perceptual hashing systems in
           | future cases. Also, thousands of PhotoDNA false positives
           | being reported in public court cases would only cause Apple's
           | reputation to collapse. They seem to have enough confidence
           | that such an extreme false positive rate is not possible to
           | the point of implementing this change. And I don't see how
           | just moving the hashing workload to the device fundamentally
           | changes the actual hashing mechanism and increases the chance
           | of wrongful conviction over the current status quo of
           | serverside scanning ( _assuming that_ it only applies to
           | images uploaded to iCloud, which could change of course). The
           | proper time to be outraged at the wrongful conviction problem
           | was ten years ago, when the major tech companies started to
           | adopt PhotoDNA.
           | 
           | On the other hand, if we're talking about what the CCP might
           | do, I would completely agree.
        
             | 7373737373 wrote:
             | > I'm not seeing how a conviction can be made on the basis
             | of a perceptual hash alone without the actual CSAM
             | 
             | This is a good point, but it's not just about people
             | getting wrongly convicted, this system even introducing a
             | remote possibility of having strangers view your personal
             | files is disturbing. In the US, it violates the 4th
             | amendment against unreasonable search, a company being the
             | middleman doesn't change that. Privacy is a shield of the
             | individual, here the presumption of innocence is deposed
             | even before the trial. An extremely low false positive rate
             | or the perceived harmlessness of the current government
             | don't matter, the systems' existence is inherently wrong.
             | It's an extension of the warrantless surveillance culture
             | modern nations are already so good at.
             | 
             | "It is better that ten guilty persons escape than that one
             | innocent suffer." -
             | https://en.wikipedia.org/wiki/Blackstone%27s_ratio
             | 
             | In a future with brain-computer interfaces, would you like
             | such an algorithm to search your mind for illegal
             | information too?
             | 
             | Is it still your device if it acts against you?
        
           | FabHK wrote:
           | > thousands of innocent people will have their most private
           | of images viewed by unaccountable strangers, will be wrongly
           | suspected or even tried and sentenced
           | 
           | Apple says: "The threshold is set to provide an extremely
           | high level of accuracy and ensures less than a one in one
           | trillion chance per year of incorrectly flagging a given
           | account."
           | 
           | What evidence do you have against that statement?
           | 
           | Next, flagged accounts are reviewed by humans. So, yes, there
           | is a minuscule chance a human might see a derivative of some
           | wrongly flagged images. But there is no reason to believe
           | that they "will be wrongly suspected or even tried and
           | sentenced".
        
             | 7373737373 wrote:
             | > Apple says: "The threshold is set to provide an extremely
             | high level of accuracy and ensures less than a one in one
             | trillion chance per year of incorrectly flagging a given
             | account."
             | 
             | I'd rather have evidence for that statement first, since
             | these are just funny numbers. I couldn't find false-
             | positive rates for PhotoDNA either. How many people have
             | been legally affected by false positives so far, how many
             | had their images viewed? The thing is, how exactly the
             | system works has to be kept secret, because it can
             | otherwise be circumvented. So these technical numbers will
             | be unverifiable. The outcomes will not, and this might be a
             | nice reason for a FOIA request.
             | 
             | But who knows, it might not matter, since it's a closed
             | source, effectively uncontrollable program running soon on
             | millions of devices against the interest of their owners
             | and no one is really accountable so false positives can be
             | treated as 'collateral damage'.
        
       | marcinzm wrote:
       | 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 before people get
       | exonerated.
        
         | TeeMassive wrote:
         | You don't even need hacking for this to be abused by malevolent
         | actors. A wife in a bad marriage could simply take nude
         | pictures of their child to falsely accuse her husband.
         | 
         | This tech is just ripe for all kind of abuses.
        
           | amannm wrote:
           | That picture wouldn't already be in the CSAM database...
        
         | remram wrote:
         | 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.
        
           | hda2 wrote:
           | The new and improved swatting.
        
           | 0x426577617265 wrote:
           | Couldn't the hack just be as simple as sending someone an
           | iMessage with the images attached? Or somehow identify/modify
           | non-illegal images to match the perceptual hash -- since it's
           | not a cryptographic hash.
        
             | barsonme wrote:
             | Does iCloud automatically upload iMessage attachments?
        
               | samename wrote:
               | No, iMessages are stored on the device until saved to
               | iCloud. However, iMessages may be backed up to iCloud, if
               | enabled.
               | 
               | The difference is photos saved are catalogued, while
               | message photos are kept in their threads.
               | 
               | Will Apple scan photos saved via iMessage backup?
        
               | 0x426577617265 wrote:
               | I would assume yes, that this would cover iMessage
               | backups since it is uploaded to their system.
        
               | 0x426577617265 wrote:
               | I think so, since the iMessages are synced across
               | devices.
        
               | tjoff wrote:
               | Doesn't need to, the detection is client side at first.
        
               | marcellus23 wrote:
               | 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.
        
               | voakbasda wrote:
               | 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?
        
               | jeromegv wrote:
               | 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.
        
               | tjoff wrote:
               | 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
               | images in the cloud as well, but they are explicit in
               | saying that it is (also) on the device itself.
        
               | wingspar wrote:
               | 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.
        
               | tjoff wrote:
               | 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.
        
               | marcellus23 wrote:
               | But what's the practical difference between scanning
               | photos when they're uploaded to iCloud on a server, or on
               | device?
        
               | tjoff wrote:
               | A world of difference. Both in practical terms and
               | principle.
               | 
               | To start, once you upload something to the cloud you do -
               | or at least are expected to - realize that it is under
               | full control of another entity.
               | 
               | Because of that you might not use iCloud or you might not
               | upload everything to iCloud.
        
               | marcellus23 wrote:
               | I think you might still be confused? Only photos being
               | uploaded to iCloud are scanned. So users can still choose
               | not to use iCloud and avoid this.
               | 
               | I certainly hope you didn't get yourself all worked up
               | without actually understanding what you're mad at :)
        
               | [deleted]
        
               | jeromegv wrote:
               | 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/app
               | le_child_safety_initia...
        
         | new_realist wrote:
         | This is already possible using other services (Google Drive,
         | gmail, Instagram, etc.) that already scan for CP.
        
           | t0mas88 wrote:
           | 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?
        
             | acdha wrote:
             | Yes: it's called PhotoDNA and is used by many, many
             | services. See https://en.wikipedia.org/wiki/PhotoDNA
             | 
             | SHA hashes aren't suitable for this: you can change a
             | single bit in the header to bypass a hash check. Perceptual
             | hashes are designed to survive cropping, rotation, scaling,
             | and embedding but all of those things mean that false-
             | positives become a concern. The real risk would be if
             | someone figured out how to many plausibly innocent
             | collisions where you could send someone a picture which
             | wasn't obviously contraband or highly suspicious and
             | attempt to convince them to save it.
        
             | bccdee wrote:
             | I'm pretty sure they use perceptual hashes for matching
             | CSAM. A lot of cloud services do this sort of thing.
        
         | gnopgnip wrote:
         | Wouldn't this risk exist already, as long as it is uploaded to
         | icloud?
        
         | seph-reed wrote:
         | Someone is going to figure out how to make false positives, and
         | then an entire genre of meme will be born from putting regular
         | memes through a false positive machine, just for the lulz.
         | 
         | Someone else could find a way to make every single possible
         | mutation of false positive Goatse/Lemonparty/TubGirl/etc. Then
         | some poor Apple employee has to check those out.
        
           | mirker wrote:
           | If Apple is indeed using CNNs, then I don't see why any of
           | the black-box adversarial attacks used today in ML wouldn't
           | work. It seems way easier than attacking file hashes, since
           | there are many images in the image space that are viable
           | (e.g., sending a photo of random noise to troll with such an
           | attack seems passable).
        
           | 0x426577617265 wrote:
           | If the process of identifying the images is done on the
           | device, then a jailbroken device will likely give an attacker
           | access to the entire DB. I'm not sure how useful it would be,
           | but if the attacker did have access to actual known CSAM
           | images it probably wouldn't be hard for them to produce false
           | positives and test it against the DB on the jailbroken
           | device, without notifying the company.
        
         | dylan604 wrote:
         | >Given past witch hunts it could be decades before people get
         | exonerated.
         | 
         | Given how pedophiles are treated in prison, that might be
         | longer than your expected lifespan if you are sent to prison
         | because of this. Of course I'm taking it to the dark place, but
         | you kinda gotta, you know?
        
         | toxik wrote:
         | This is really a difficult problem to solve I think. However, I
         | think most people who are prosecuted for CP distribution are
         | hoarding it by the terabyte. It's hard to claim that you were
         | unaware of that. A couple of gigabytes though? Plausible. And
         | that's what this CSAM scanner thing is going to find on phones.
        
           | emodendroket wrote:
           | A couple gigabytes is a lot of photos... and they'd all be
           | showing up in your camera roll. Maybe possible but stretching
           | the bounds of plausibility.
        
             | giantrobot wrote:
             | The camera roll's defaults display images chronologically
             | based on the image's timestamp. I've got thousands of
             | photos on my phone going back _years_.
             | 
             | If you hack my phone and plant some photos with a
             | sufficiently old timestamp I'd never notice them. I can't
             | imagine my situation is all that uncommon either.
        
             | MinusGix wrote:
             | As others have said, people have a lot of photos. It
             | wouldn't be too hard to hide them a bit from obvious view.
             | As well, I rarely look at my gallery unless I need to. I
             | just add a few photos occasionally. So maybe once every two
             | weeks I look at my gallery, plenty of time to initiate
             | that.
        
             | runlevel1 wrote:
             | Gigs of software updates and podcast episodes are regularly
             | downloaded to phones without being noticed.
             | 
             | How frequently do most people look at their camera roll?
             | I'd be surprised if it's more than a few times a week on
             | average.
             | 
             | Does an attacker even need access to the phone? If iCloud
             | is syncing your photos, your phone will eventually see all
             | your pictures. Unless I've misunderstood how this works,
             | the attacker only needs access to your iCloud account.
        
               | kelnos wrote:
               | > _I 'd be surprised if it's more than a few times a week
               | on average._
               | 
               | For me it's probably 5-7 times per _day_ , but I also
               | take a lot of photos.
               | 
               | I think a few times a week is probably low-balling it,
               | even for an average.
        
               | Mirioron wrote:
               | I see my camera reel about once every few months. If I'm
               | not taking a picture I don't see the reel.
        
             | danachow wrote:
             | A couple gigabytes is enough to ruin someone's day but not
             | a lot to surreptitiously transfer, it's literally seconds.
             | Just backdate them and they may very well go unnoticed.
        
               | tornato7 wrote:
               | It's also possible to 'hide' photos from the reel in the
               | photos app. Many people are unaware of that feature so an
               | attacker could hide as many photos they want in your
               | iCloud.
        
               | l33t2328 wrote:
               | How do you do that?
        
               | imwillofficial wrote:
               | Assmuning they have access
        
               | pixl97 wrote:
               | With the number of security flaws that exist these days
               | we should assume someone always has access that is not
               | intended.
        
           | 0x426577617265 wrote:
           | Why would they hoard it in the camera/iPhotos app? I assume
           | that storage is mostly pictures taken with the device.
           | Wouldn't this be the least likely place to find a hoard of
           | known images?
        
       | BiteCode_dev wrote:
       | The problem is not perceptual hashes. The problem is the back
       | door. Let's not focus on the defect of the train leading you to
       | the concentration camp. The problem is that there is a camp at
       | the end of the rail road.
        
       | ezoe wrote:
       | 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 that match the hash to the
       | authority. The authority use that report for a convenient reason
       | to false-arrest you.
       | 
       | Now what happens if you sue the authority for the intentional
       | false-arrest? Demand the original intended file for the hash?
       | "No. We won't reveal the original file because it's child abusing
       | image, also we don't keep the original file for moral reason"
       | 
       | But come to think of it, we already have tons of such bogus
       | pseudo-science technology like the dogs which conveniently bark
       | at police's secret hand sign, polygraph, and the drug test kit
       | which detect illegal drugs from thin air.
        
         | jokoon wrote:
         | > Suppose the authority want to false-arrest you.
         | 
         | Why would they want that?
        
           | awestroke wrote:
           | Oh, sweet, naive child.
        
             | jokoon wrote:
             | I'm not american, I'm just asking a simple question.
        
               | awestroke wrote:
               | Corrupt governments and police forces are not unique to
               | the US (although it seems like the police in the US has
               | become corrupt through and through).
        
               | [deleted]
        
               | l33t2328 wrote:
               | Are you from a country where the government has never
               | abused its power?
        
               | kleene_op wrote:
               | This has nothing to do with America.
        
               | [deleted]
        
             | latexr wrote:
             | Be kind[1]. Not everyone will have a life experience or
             | knowledge similar to yours. Someone looking to fill the
             | gaps in their knowledge in good faith should be encouraged,
             | not ridiculed.
             | 
             | [1]: https://news.ycombinator.com/newsguidelines.html
        
           | nicce wrote:
           | Corruption. Lack of evidence on some other cases. Personal
           | revenge. Who knows, but list is big.
        
             | jokoon wrote:
             | Ok but but what ends?
        
               | latexr wrote:
               | Imagine you're a journalist uncovering corruption
               | perpetrated by the police force or a politician. Can you
               | see how they would be incentivised to arrest you on false
               | charges to halt the investigation and protect themselves?
        
           | ATsch wrote:
           | This is a pretty weird question considering the mountains of
           | documentation of authorities doing just that. This is not
           | some kind of hypothetical that needs extraordinary
           | justification.
        
         | delusional wrote:
         | What about trolling. Assume 4chan figures out apples algorithm.
         | What now happens when they start generating memes that happen
         | to match known child pornography? Will anyone who saves those
         | memes (or repost them to reddit/facebook) be flagged? What will
         | apple do once flagged false positive photos go viral?
        
           | [deleted]
        
           | sunshinerag wrote:
           | >> Will anyone who saves those memes (or repost them to
           | reddit/facebook) be flagged?
           | 
           | Shouldn't they be?
        
             | Frost1x wrote:
             | The point made was that there are always flaws in these
             | sorts of approaches that lead to false positives. If you
             | can discover the flawed pattern(s) that leads to false
             | positives and engineer them into seemingly harmless images,
             | you can quite literally do what OP I'd suggesting. It's a
             | big IFF but it's not theoretically impossible.
             | 
             | The difference between this and hashes that require image
             | data to be almost identical is that someone who accidently
             | sees it can avoid and report it. If I can make cat photos
             | that set off Apple's false positives, then there's a lot of
             | people who will be falsely accused of propagating child
             | abuse photos when they're really just sending cat memes.
        
             | paulryanrogers wrote:
             | Umm, no? If someone happens upon some funny cat meme that
             | 4chan users made with an intentional hash collision then
             | they're not guilty of anything.
             | 
             | A poor analogy could be trolls convincing a flash mob to
             | dress like a suspect's description which they overheard
             | with a police scanner. No one in the mob is guilty of
             | anything more than poor fashion choice.
        
           | mirkules wrote:
           | One way this hair-brained Apple program could end is to
           | constantly generate an abundance of false positives, and try
           | to render it useless.
           | 
           | For those old enough to remember "Jam Echelon Day", maybe it
           | won't have any effect. But what other recourse do we have
           | other than to maliciously and intentionally subvert and break
           | it?
        
         | ATsch wrote:
         | The way I see it, this is the only possible purpose this system
         | could have. With the press after this announcement, almost
         | every single person in posession of those materials knows it's
         | not safe to store them on an iPhone. By it's construction, this
         | system can only be effective against things that the owner is
         | not aware their phones are being searched for.
        
         | emodendroket wrote:
         | Parallel construction is another way this is often pursued.
        
         | some_random wrote:
         | The police can arrest you for laws that don't exist but they
         | _think_ exist. They don 't need to any of this stuff.
        
         | nullc wrote:
         | > Demand the original intended file for the hash?
         | 
         | Even if they'd provide it-- the attacker need only perturb an
         | image from an existing child abuse image database until it
         | matches the target images.
         | 
         | Step 1. Find images associated with the race or political
         | ideology that you would like to genocide and compute their
         | perceptual hashes.
         | 
         | Step 2. Obtain a database of old widely circulated child porn.
         | (Easy if you're a state actor, you already have it, otherwise
         | presumably it's obtainable since if it wasn't none of this
         | scanning would be needed).
         | 
         | Step 3. Scan for the nearest perceptual matches for the target
         | images in the CP database. Then perturb the child porn images
         | until they match (e.g. using adversarial noise).
         | 
         | Step 4. Put the modified child porn images into circulation.
         | 
         | Step 5. When these in-circulation images are added to the
         | database the addition is entirely plausibly denyable.
         | 
         | Step 6. After rounding up the targets, even if they're allowed
         | any due process at all you disallow them access to the images.
         | If that dis-allowance fails, you can still cover by the images
         | existing and their addition having been performed by someone
         | totally ignorant of the scheme.
        
         | thaumasiotes wrote:
         | > 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.
        
           | intricatedetail wrote:
           | Dogs are used to protect police from accusations of racism
           | and profiling.
        
             | pixl97 wrote:
             | Which is odd as dogs can be just as racist as their
             | handlers want.
        
           | exporectomy wrote:
           | 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.
        
             | [deleted]
        
             | thaumasiotes wrote:
             | https://reason.com/2021/05/13/the-police-dog-who-cried-
             | drugs...
             | 
             | > Similar patterns abound nationwide, suggesting that
             | Karma's career was not unusual. Lex, a drug detection dog
             | in Illinois, alerted for narcotics 93 percent of the time
             | during roadside sniffs, but was wrong in more than 40
             | percent of cases. Sella, a drug detection dog in Florida,
             | gave false alerts 53 percent of the time. Bono, a drug
             | detection dog in Virginia, incorrectly indicated the
             | presence of drugs 74 percent of the time.
        
               | dagw wrote:
               | I've had my bag sniffed at airports at least 50 times,
               | and they've never stopped me. So there must be something
               | else going on as well
        
               | jsjohnst wrote:
               | Airport dogs (at least in the baggage claim area) are not
               | sniffing for drugs. They alert on food products that
               | aren't allowed.
        
               | emodendroket wrote:
               | The police only call in the dogs when they wish to search
               | and the driver does not agree. The airport doesn't do
               | things this way so the same strategy wouldn't work.
        
               | pixl97 wrote:
               | The handler didn't think you looked untrustworthy and
               | didn't hint for the dog to bark.
        
               | fortran77 wrote:
               | Drug detection dogs sit down near the bag. They don't
               | bark.
        
               | burnte wrote:
               | I was pulled over in West Baton Rouge in 2009, we were
               | driving east in an empty rental box truck after helping a
               | friend move back to Tx. It was 1am, we were pulled over
               | on a BS pretense (weaving across lanes when we signaled a
               | lane change because they had someone else pulled over, so
               | we obeyed the law of pulling over a lane to give them
               | room). I denied their request to search the truck, they
               | had no reason. They called the drug dog, who after the
               | third walk around, "signaled" drugs at the right front
               | tire (after having thir leash jerked). They then "had
               | cause" to search the truck. After finding two small
               | suitcases with clothes (exactly what we told them they'd
               | find), the main cop got really angry with me for "making
               | a mockery of the south", threw the keys at me and told us
               | to GTFO.
               | 
               | I'm 100% convinced drug dogs are trained to "signal"
               | falsely at certain things like a leash tug. It's all BS.
        
               | wpietri wrote:
               | Yikes. Seems like the biggest group of people making a
               | mockery of the south is the southerners like this guy who
               | insist on acting like cartoonish southern stereotypes.
               | 
               | I should also add that dogs and many other animals really
               | like pleasing people. So one doesn't even have to
               | consciously train for outcomes like this. A famous
               | example is Clever Hans, the horse that supposedly could
               | read, do math, and answer questions like "If the eighth
               | day of the month comes on a Tuesday, what is the date of
               | the following Friday?"
               | https://en.wikipedia.org/wiki/Clever_Hans
        
               | imwillofficial wrote:
               | Out of how many dogs? We're these outliers or the regular
               | thing?
        
               | stickfigure wrote:
               | What feedback loop is built into the system to discourage
               | this from being the regular thing?
        
         | [deleted]
        
         | fogof wrote:
         | 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.
        
           | BiteCode_dev wrote:
           | 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.
        
             | sharken wrote:
             | 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.
        
               | CRConrad wrote:
               | > 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
        
           | gpm wrote:
           | It wouldn't prove anything, because hash functions are many-
           | to-one. It's entirely possible that it was just a
           | coincidence.
        
           | dannyw wrote:
           | There are literally hundreds of cases of police fabricating
           | evidence and getting caught in court, or on bodycam.
           | 
           | This happens today. We must not build technology that makes
           | it even more devastating.
        
           | [deleted]
        
           | nicce wrote:
           | "Sorry, but collisions happen with all hashing algorithms,
           | and you can't prove otherwise. It is just a matter of time.
           | Nothing to see here."
        
             | nullc wrote:
             | In the past the FBI used some cryptographic hash.
             | Collisions with a secure cryptographic hash are
             | functionally unobservant in practice (or else the hash is
             | broken).
             | 
             | The use of the perceptual hash is because some people might
             | evade the cryptographic hash by making small modifications
             | to the image. The fact that they'd discarded the protection
             | of cryptographic hashing just to accommodate these extra
             | matches is unsurprising because their behavior is largely
             | unconstrained and unbalanced by competing factors like the
             | public's right to privacy or your security against being
             | subject to a false accusation.
        
             | Frost1x wrote:
             | Well, not _all_ hashing algorithms but all _interesting_ or
             | considered _useful_ hashing algorithms, probably.
             | 
             | When dealing with say countable infinite sets you can
             | certainly create a provable unique hash for each item in
             | that set. The hash won't be interesting or useful. E.g. a
             | hash that indexes all the integers n with a hashing
             | function h(n+1)... so every integer you hash will be that
             | value plus one. But this just being pedantic and wanting to
             | walk down the thought.
        
           | visarga wrote:
           | You can reveal your files and people can accuse you you
           | deleted the incriminating ones.
        
             | kelnos wrote:
             | Not if you show the file that matches the perceptual hash
             | that "caught" you.
        
               | cotillion wrote:
               | So Apple-users can no longer delete any pictures since
               | Apple might already have reported that photo you
               | accidentally took of your thumb as CP.
        
               | deanclatworthy wrote:
               | Would a court be compelled to provide that hash to your
               | defence? Arguable as it could be used by criminals to
               | clean their collection. And by that time your life is
               | ruined anyway.
        
       | [deleted]
        
       | yellow_lead wrote:
       | Regarding false positives re:Apple, the Ars Technica article
       | claims
       | 
       | > Apple offers technical details, claims 1-in-1 trillion chance
       | of false positives.
       | 
       | There are two ways to read this, but I'm assuming it means, for
       | each scan, there is a 1-in-1 trillion chance of a false positive.
       | 
       | Apple has over 1 billion devices. Assuming ten scans per device
       | per day, you would reach one trillion scans in ~100 days. Okay,
       | but not all the devices will be on the latest iOS, not all are
       | active, etc, etc. But this is all under the assumption those
       | numbers are accurate. I imagine reality will be much worse. And I
       | don't think the police will be very understanding. Maybe you will
       | get off, but you'll be in a huge debt from your legal defense. Or
       | maybe, you'll be in jail, because the police threw the book at
       | you.
        
         | wilg wrote:
         | Apple claims that metric for a false positive account flagging,
         | not photo matching.
         | 
         | > The threshold is set to provide an extremely high level of
         | accuracy and ensures less than a one in one trillion chance per
         | year of incorrectly flagging a given account.
         | 
         | https://www.apple.com/child-safety/
        
           | yellow_lead wrote:
           | Good find
        
         | KarlKemp wrote:
         | Do you really believe that if they scan your photo library at
         | 10am and don't get any false positives, another scan five hours
         | later, with no changes to the library, has the same chance of
         | getting false positives as the first one, independent of that
         | result?
        
           | burnished wrote:
           | If you take photos, then yes?
        
           | NoNotTheDuo wrote:
           | Even if the library doesn't change, doesn't the possibility
           | of the list of "bad" hashes changing exist? I.e., in your
           | example, a new hash is added to by Apple to the list at
           | 11:30am, and then checked against your unchanged library.
        
             | IfOnlyYouKnew wrote:
             | Oh god have mercy on whatever has happened to these
             | people...
        
         | nanidin wrote:
         | > Apple has over 1 billion devices. Assuming ten scans per
         | device per day, you would reach one trillion scans in ~100
         | days.
         | 
         | People like to complain about the energy wasted mining
         | cryptocurrencies - I wonder how this works out in terms of
         | energy waste? How many people will be caught and arrested by
         | this? Hundreds or thousands? Does it make economic sense for
         | the rest of us to pay an electric tax in the name of scanning
         | other people's phones for this? Can we claim it as a deductible
         | against other taxes?
        
           | FabHK wrote:
           | > I wonder how this works out in terms of energy waste?
           | 
           | Cryptocurrency waste is vastly greater. It doesn't compare at
           | all. Crypto wastes as much electricity as a whole country.
           | This will lead to a few more people being employed by Apple
           | to verify flagged images, that's it.
        
             | nanidin wrote:
             | In net terms, you're probably right. But at least the
             | energy used for cryptocurrency is being used toward
             | something that might benefit many (commerce, hoarding,
             | what-have-you), vs against something that might result in
             | the arrest of few.
             | 
             | The economics I'm thinking of are along the lines of
             | cryptocurrency energy usage per participant, vs image
             | scanning energy per caught perpetrator. The number of
             | caught perpetrators via this method over time will approach
             | zero, but we'll keep using energy to enforce it forever.
             | 
             | All this does is remove technology from the problem of
             | child abuse, it doesn't stop child abuse.
        
         | dylan604 wrote:
         | knowing Apple, the initial scan of this will be done while the
         | phone is on charge just like previous versions of scanning your
         | library. However, according to Apple it is just the photos
         | shared with iCloud. So since it's on a charger, it's minimal
         | electron abuse.
         | 
         | Once you start adding new content from camera to iCloud, I'd
         | assume the new ML chips of Apple Silicone will be calculating
         | the phashes as part-and-parcel to everything else it does. So
         | unless you're trying to "recreate" known CP, then new photos
         | from camera really shouldn't need this hashing done to them.
         | Only files not originated from the user's iDevice should
         | qualify. If a CP creator is using an iDevice, then their new
         | content won't match existing hashes, so what's that going to
         | do?
         | 
         | So so many questions. It's similar yet different to mandatory
         | metal detectors and other screening where 99.99% of people are
         | innocent and "merely" inconvenienced vs the number of people
         | any of that screening catches. Does the mere existence of that
         | screening act as a deterent? That's like asking how many angels
         | can stand on the head of a pin. It's a useless question. The
         | answer can be whatever they want it to be.
        
         | axaxs wrote:
         | Eh...I don't think of it as one in a trillion scans...but one
         | in a trillion chance per image. I have something like 2000
         | pics. My wife, at least 5x that number. If we split the
         | difference, and assume the average device has 5000 pics, that's
         | already hitting false positives multiple times. Feel sorry for
         | the first 5 to get their account banned on day 1 because their
         | pic of an odd piece of toast was reported to the govt as cp.
        
           | [deleted]
        
       | kazinator wrote:
       | Perceptual hashing was invented by the Chinese: four-corner code
       | character lookup, that lumps together characters with similar
       | features.
        
       | acidioxide wrote:
       | It's really disturbing that, in case of doubt, real person would
       | check photos. That's a red flag.
        
       | klodolph wrote:
       | > Even at a Hamming Distance threshold of 0, that is, when both
       | hashes are identical, I don't see how Apple can avoid tons of
       | collisions...
       | 
       | You'd want to look at the particular perceptual hash
       | implementation. There is no reason to expect, without knowing the
       | hash function, that you would end up with tons of collisions at
       | distance 0.
        
         | mirker wrote:
         | If images have cardinality N and hashes M and N > M, then yes,
         | by pigeonhole principle you will have collisions regardless of
         | hash function, f: N -> M.
         | 
         | N is usually much bigger than M, since you have the
         | combinatorial pixel explosion. Say images are 8 bit RGB
         | 256x256, then you have 2^(8x256x256x3) bit combinations. If you
         | have a 256-bit hash, then that's only 2^256. So there is a
         | factor of 2^(8x256x3) difference between N and M if I did my
         | math right, which is a factor I cannot even calculate without
         | numeric overflow.
        
           | klodolph wrote:
           | The number of possible different images doesn't matter, it's
           | only the number of actually different images encountered in
           | the world. This number cannot be anywhere near 2^256, that
           | would be physically impossible.
        
             | mirker wrote:
             | But you cannot know that a-priori so it's either an attack
             | vector for image manipulation or straight up false
             | positives.
             | 
             | Assume we had this perfect hash knowledge. I'd create a
             | compression algorithm to uniquely map between images and
             | the 256 bit hash space, which we probably agree is
             | similarly improbable. It's on the order of 1000x to 10000x
             | more efficient than JPEG and isn't even lossy.
        
               | klodolph wrote:
               | You're going to have to explain that--what is an attack
               | vector for image manipulation? What is an attack vector
               | for false positives?
               | 
               | > Assume we had this perfect hash knowledge.
               | 
               | It's not a perfect hash. Nobody's saying it's a perfect
               | hash. It's not. It's a perceptual hash. It is
               | _specifically designed_ to map similar images to similar
               | hashes, for the "right" notion of similar.
        
       | cratermoon wrote:
       | If I'm reading this right? Apple is saying they are going to flag
       | CSAM they find on their servers. This article talks about finding
       | a match for photos by comparing a hash of a photo you're testing
       | with a hash you have, from a photo you have.
       | 
       | Does this mean Apple had/has CSAM available to generate the
       | hashes?
        
         | [deleted]
        
         | aix1 wrote:
         | For the purposes of this they only have the hashes, which they
         | receive from third parties.
         | 
         | > on-device matching using a database of known CSAM image
         | hashes provided by NCMEC and other child safety organizations
         | 
         | https://www.apple.com/child-safety/
         | 
         | (Now, I do wonder how secure those third parties are.)
        
       | SavantIdiot wrote:
       | This article covers three methods, all of which just look for
       | alterations of a source image to find a fast match (in fact,
       | that's the paper referenced). It is still a "squint to see if it
       | is similar" test. I was under the impression there were more
       | sophisticated methods that looked for _types_ of images, not just
       | altered known images. Am I misunderstanding?
        
         | chipotle_coyote wrote:
         | Apple's proposed system compares against a database of known
         | images. I can't think of a way to "look for types of images"
         | other than trying to do it with machine learning, which strikes
         | me as fraught with incredible fiasco potential. (The compare-
         | to-a-known-database approach has its own issues, including the
         | ones the article talks about, of course.)
        
           | SavantIdiot wrote:
           | Ok, that's what it is seeming like. Since a crypto hash by
           | definition has to generate a huge hamming distance for a
           | small change, everything i've read about perceptual hashes is
           | just the opposite: they should be tolerant enough of a
           | certain amount of difference.
        
       | siscia wrote:
       | What I am missing from all this story, is what triggered Apple to
       | put in place, or even think about, this system.
       | 
       | It is clearly a no-trivial project, no other company is doing it,
       | and it will be one of the rare case of a company doing something
       | not for shareholders value but for "goodwill".
       | 
       | I am really not understanding the reasoning behind this choice.
        
         | jeromegv wrote:
         | One theory is that they are getting ready for E2E encryption of
         | iCloud photos. Apple will have zero access to your photos in
         | the cloud. So the only way to get the authorities to accept
         | this new scheme is that there is this backdoor where there is a
         | check client-side for sexual predator photos. Once your photo
         | pass that check locally, it gets encrypted, sent to the cloud,
         | never to be decrypted by apple.
         | 
         | Not saying it will happen, but that's a decent theory as of why
         | https://daringfireball.net/2021/08/apple_child_safety_initia...
        
         | spacedcowboy wrote:
         | Er, every US company that hosts images in the cloud scans them
         | for CSAM if they have access to the photo, otherwise they're
         | opening themselves up to a lawsuit.
         | 
         | US law requires any ESP (electronic service provider) to alert
         | NCMEC if they become aware of CSAM on their servers. Apple used
         | to comply with this by scanning images on the server in iCloud
         | photos, and now they're moving that to the device _if_ that
         | image is about to be uploaded to iCloud photos.
         | 
         | FWIW, the NYT says Apple reported 265 cases last year to NCMEC,
         | and say Facebook reported 20.3 million. Google [1] are on for
         | 365,319 for July->Dec.
         | 
         | I'm still struggling to see what has changed here, apart from
         | people _realising_ what's been happening..
         | 
         | - it's the same algorithm that Apple has been using, comparing
         | NCMEC-provided hashes against photos
         | 
         | - it's still only being done on photos that are uploaded to
         | iCloud photos
         | 
         | - it's now done on-device rather than on-server, which removes
         | a roadblock to future e2e encryption on the server.
         | 
         | Seems the only real difference is perception.
         | 
         | [1] https://transparencyreport.google.com/child-sexual-abuse-
         | mat...
        
         | MontagFTB wrote:
         | Legally, I believe, they are responsible for distribution of
         | CSAM that may wind up in their cloud, regardless of who put it
         | there. Many cloud companies are under considerable legal
         | pressure to find and report it.
        
       | altitudinous wrote:
       | This article focusses too much on the individual case, and not
       | enough on the fact that Apple will need multiple matches to
       | report someone. Images would normally be distributed in sets I
       | suspect, so it is going to be easy to detect when someone is
       | holding an offending set because of multiple matches. I don't
       | think Apple are going to be concerned with a single hit. Here in
       | the news offenders are reported as holding many thousands of
       | images.
        
         | trynumber9 wrote:
         | Does it scan files within archives?
         | 
         | If it does, you could download the wrong zip and
         | instantaneously be over their threshold.
        
           | altitudinous wrote:
           | The scanning is to take place within iCloud Photos, which
           | handles images / videos etc on an individual basis. It would
           | be a pretty easy thing to do for Apple to calculate hashes on
           | these. I'm not sure how iOS handles archives, but it doesn't
           | matter - remember it isn't 100% or 0% with these things - say
           | only 50% of those people store images in iCloud Photo,
           | catching out only 50% of those folk is still a good result.
        
             | trynumber9 wrote:
             | Yeah, I'm not sure. Just is a bit worrying to me. On my
             | device iCloud Drive synchronizes anything in my downloads
             | folder. If images contained within zips are treated as
             | individual images, then I'm always just one wrong click
             | from triggering their threshold.
        
       | jbmsf wrote:
       | I am fairly ignorant if this space. Do any of the standard
       | methods use multiple hash functions vs just one?
        
         | jdavis703 wrote:
         | Yes, I worked on such a product. Users had several hashing
         | algorithms they could chose from, and the ability to create
         | custom ones if they wanted.
        
         | heavyset_go wrote:
         | I've built products that utilize different phash algorithms at
         | once, and it's entirely possible, and quite common, to get
         | false positives across hashing algorithms.
        
       | JacobiX wrote:
       | Given that Apple technology uses NN and triplet embedding loss,
       | the exact same techniques used by neural networks for face
       | recognition, so maybe the same shortcomings would apply here. For
       | example a team of researchers found a 'Master Faces' that can
       | bypass over 40% of Facial ID. Now suppose that you have such an
       | image in your photo library, it would generate so many false
       | positives ...
        
       | lordnacho wrote:
       | Why wouldn't the algo check that one image has a face while the
       | other doesn't? That would remove this particular false positive,
       | though I'm not sure what it might cause of new ones.
        
         | PUSH_AX wrote:
         | Because where do you draw the line with classifying arbitrary
         | features in the images? The concept is it should work with an
         | image of anything.
        
       | legulere wrote:
       | Which photos does Apple scan? Also of emails and messages? Could
       | you swat somebody by sending them benign images that have the
       | same hash?
        
       | rustybolt wrote:
       | > 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.
        
         | hnick wrote:
         | Yes, private nude pictures of other people's children too,
         | which do not necessarily constitute pornography. It was common
         | when I was young for parents to take pictures of their kids
         | doing things, clothes or not. Some still exist of me I'm sure.
         | 
         | So far as I know some parents still do this. I bet they'd be
         | thrilled having Apple employees look over these.
        
         | emodendroket wrote:
         | And what do you think the content moderation teams employed by
         | Facebook, YouTube, et al. do all day?
        
           | mattigames wrote:
           | Yeah, we obviously needed one more company doing it as well,
           | and I'm sure having more positions in the job market which
           | pretty much could be described as "Get paid to watch
           | pedophilia all day long" will not backfire in any way.
        
             | emodendroket wrote:
             | You could say there are harmful effects of these jobs but
             | probably not in the sense you're thinking.
             | https://www.wired.com/2014/10/content-moderation/
        
           | mattnewton wrote:
           | There's a big difference in the expectation of privacy
           | between what someone posts on "Facebook, Youtube, et al" and
           | what someone takes a picture of but doesn't share.
        
             | spacedcowboy wrote:
             | Odd, then, that Facebook reported 20.3 million photos to
             | NCMEC last year, and Apple 265, according to the NYT that
             | is.
        
             | emodendroket wrote:
             | A fair point but, again, quite aside from the concern being
             | raised about moderators having to view potentially illegal
             | content.
        
             | alkonaut wrote:
             | Couldn't they always avoid ever flagging pictures taken on
             | the device itself (camera, rather than download) since if
             | those match, it's always a false positive?
        
           | josephcsible wrote:
           | They look at content that people actively and explicitly
           | chose to share with wider audiences.
        
             | emodendroket wrote:
             | While that's a snappy response, it doesn't seem to have
             | much to do with the concern about perverts getting jobs
             | specifically to view child abuse footage, which is what I
             | thought this thread was about.
        
               | CRConrad wrote:
               | I didn't think that was what it's about... Because that
               | didn't even occur to me. Thanks for pointing it out.
        
               | [deleted]
        
           | techbio wrote:
           | 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.
        
           | [deleted]
        
         | Spivak wrote:
         | Yep! I guess this announcement is when everyone is collectively
         | finding out how this has, apparently quietly, worked for years.
         | 
         | It's a "killing floor" type job where you're limited in how
         | long you're allowed to do it in a lifetime.
        
         | varjag wrote:
         | There are people who are paid to do that already, just
         | generally not in corporate employment.
        
         | pkulak wrote:
         | Apple, with all those Apple == Privacy billboards plastered
         | everywhere, is going to have a full-time staff of people with
         | the job of looking through it's customers' private photos.
        
           | arvinsim wrote:
           | Sue them for false marketing.
        
         | mattigames wrote:
         | I'm sure thats the dream position for most pedophiles, watching
         | child porn fully legally and being paid for it, plus on the
         | record being someone who helps destroy it; and given that CP
         | will exist for as long as human beings do there will be no
         | shortage no matter how much they help capturing other
         | pedophiles.
        
       | ivalm wrote:
       | I am not exactly buying the premise here, if you train a CNN on
       | useful semantic categories then the representations they generate
       | will be semantically meaningful (so the error shown in blog
       | wouldn't occur).
       | 
       | I dislike the general idea of iCloud having back doors but I
       | don't think the criticism in this blog is entirely valid.
       | 
       | Edit: it was pointed out apple doesn't have semantically
       | meaningful classifier so the blog post's criticism is valid.
        
         | jeffbee wrote:
         | I agree the article is a straw-man argument and is not
         | addressing the system that Apple actually describes.
        
         | SpicyLemonZest wrote:
         | Apple's description of the training process
         | (https://www.apple.com/child-
         | safety/pdf/CSAM_Detection_Techni...) sounds like they're just
         | training it to recognize some representative perturbations, not
         | useful semantic categories.
        
           | ivalm wrote:
           | Ok, good point, thanks.
        
       | Wowfunhappy wrote:
       | > At my company, we use "perceptual hashes" to find copies of an
       | image where each copy has been slightly altered.
       | 
       | Kind of off topic, does anyone happen to know of some good
       | software for doing this on a local collection of images? A common
       | sequence of events at my company:
       | 
       | 1. We're designing a website for some client. They send us a
       | collection of a zillion photos to pull from. For the page about
       | elephants, we select the perfect elephant photo, which we crop,
       | _lightly_ recolor, compress, and upload.
       | 
       | 2. Ten years later, this client sends us a screenshot of the
       | elephant page, and asks if we still have a copy of the original
       | photo.
       | 
       | Obviously, absolutely no one at this point remembers the name of
       | the original photo, and we need to either spend hours searching
       | for it or (depending on our current relationship) nicely explain
       | that we can't help. It would be really great if we could do
       | something like a reverse Google image search, but for a local
       | collection. I know it's possible to license e.g. TinEye, but it's
       | not practical for us as a tiny company. What I really want is an
       | open source solution I can set up myself.
       | 
       | We used Digicam for a while, and there were a couple of times it
       | was useful. However, for whatever reason it seemed to be
       | extremely crash-prone, and it frequently couldn't find things it
       | really should have been able to find.
        
         | xioren00 wrote:
         | https://pypi.org/project/ImageHash/
        
           | Wowfunhappy wrote:
           | Thank you!
        
       | brian_herman wrote:
       | Fortunately I have a cisco router and enough knowledge to block
       | the 17.0.0.0/8 ip address range. This combined with an openvpn
       | vpn will block all apple services from my devices. So basically
       | my internet will look like this:
       | 
       | Internet <---> CISCO <---> ASUS ROUTER with openvpn <-> Network
       | The cisco router will block the 17.0.0.0/8 ip address range and I
       | will use spotify on all my computers.
        
         | verygoodname wrote:
         | And then they switch to using Akamai or AWS IP space (like
         | Microsoft does), so you start blocking those as well?
        
         | brian_herman wrote:
         | Disregard comment I don't want to edit it because I am lazy.
         | You can do all of this inside the asus router underneath the
         | routes page just put this inside the asus router: Ip address
         | 17.0.0.0 Subnet 255.0.0.0 Destination 127.0.0.1
        
           | procinct wrote:
           | You don't plan to ever use 4G/5G again?
        
             | brian_herman wrote:
             | I have openvpn so the block will remain in effect. I don't
             | plan to use apple services ever again but the hard ware is
             | pretty good.
        
               | loser777 wrote:
               | Does this mean you are attempting to use an IP range
               | block to avoid this "service" while continuing to use
               | Apple hardware? How does such a block deal with say,
               | Apple software conveniently "routing-around" what appears
               | to be an "authoritarian government's firewall?"
        
       | ngneer wrote:
       | What is the ratio of consumers of child pornography to the
       | population of iPhone users? In order of magnitude, is it 1%,
       | 0.1%, 0.001%, 0.0001%? With all the press around the
       | announcement, this is not exactly stealth technology. Wouldn't
       | such consumers switch platforms, rendering the system pointless?
        
         | aix1 wrote:
         | It's clearly a marketing exercise aimed to sell products to
         | parents and other concerned citizens. It doesn't actually need
         | to be effective to achieve this goal. (I am not saying whether
         | it will or won't be, just that it doesn't _need_ to be.)
        
       | ajklsdhfniuwehf wrote:
       | whatsapp and other apps place pictures from groups chats in
       | folders deep in your IOS gallery.
       | 
       | Swatting will be a problem all over again.... wait, did it ever
       | stop being a problem?
        
       | btheshoe wrote:
       | I'm not insane in thinking this stuff has to be super vulnerable
       | to adversarial attacks, right? And it's not like adversarial
       | attacks are a solved problem or anything.
        
         | aix1 wrote:
         | Yes, I agree that this is a significant risk.
        
         | mkl wrote:
         | Wouldn't you need a way to determine if an image you generate
         | has a match in Apple's database?
         | 
         | The way it's set up, that's not possible: "Given a user image,
         | the general idea in PSI is to apply the same set of
         | transformations on the image NeuralHash as in the database
         | setup above and do a simple lookup against the blinded known
         | CSAM database. However, the blinding step using the server-side
         | secret is not possible on device because it is unknown to the
         | device. The goal is to run the final step on the server and
         | finish the process on server. _This ensures the device doesn't
         | know the result of the match_ , but it can encode the result of
         | the on-device match process before uploading to the server." --
         | https://www.apple.com/child-safety/pdf/CSAM_Detection_Techni...
         | (emphasis mine)
        
       | Waterluvian wrote:
       | I'm rather fascinated by the false matches. Those two images are
       | very different and yet beautifully similar.
       | 
       | I want to see a lot more pairs like this!
        
       | asimpletune wrote:
       | " Even at a Hamming Distance threshold of 0, that is, when both
       | hashes are identical, I don't see how Apple can avoid tons of
       | collisions, given the large number of pictures taken every year
       | (1.4 trillion in 2021, now break this down by iPhone market share
       | and country, the number for US iPhone users will still be
       | extremely big)."
       | 
       | Is this true? I'd imagine you could generate billions a second
       | without having a collision, although I don't know much about how
       | these hashes are produced.
       | 
       | It would be cool for an expert to weigh in here.
        
       | ChrisMarshallNY wrote:
       | That's a really useful explanation.
       | 
       | Thanks!
        
       | karmakaze wrote:
       | It really all comes down to if Apple has and is willing to
       | maintain the effort of human evaluations prior to taking action
       | on the potentially false positives:
       | 
       | > According to Apple, a low number of positives (false or not)
       | will not trigger an account to be flagged. But again, at these
       | numbers, I believe you will still get too many situations where
       | an account has multiple photos triggered as a false positive.
       | (Apple says that probability is "1 in 1 trillion" but it is
       | unclear how they arrived at such an estimate.) These cases will
       | be manually reviewed.
       | 
       | At scale, even human classification which ought to be clear will
       | fail, accidentally clicking 'not ok' when they saw something they
       | thought was 'ok'. It will be interesting to see what happens
       | then.
        
         | jdavis703 wrote:
         | Then law enforcement, a prosecutor and a jury would get
         | involved. Hopefully law enforcement would be the first and
         | final stage if it was merely the case that a person pressed
         | "ok" by accident.
        
           | karmakaze wrote:
           | This is exactly the kind of thing that is to be avoided:
           | premature escalation, tying up resources, increasing costs,
           | and raising the stakes and probability of bad outcomes.
        
       | at_a_remove wrote:
       | 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 JPEG. I
       | resized it slightly. I trimmed some edges. I adjusted colors. I
       | did a one degree rotation. Only after a reasonably complete
       | combination of those factors would the image make it through. How
       | interesting!
       | 
       | I just don't know how well this little venture of Apple's will
       | scale, and I wonder if it won't even up being easy enough to
       | bypass in a variety of ways. I think the tradeoff will do very
       | little, as stated, but is probably a glorious apportunity for
       | black-suited goons of state agencies across the globe.
       | 
       | We're going to find out in a big big way soon.
       | 
       | * The image is of the back half of a Sphynx cat atop a CRT. From
       | the angle of the dangle, the presumably cold, man-made feline is
       | draping his unexpectedly large testicles across the similarly
       | man-made device to warm them, suggesting that people create
       | problems and also their solutions, or that, in the Gibsonian
       | sense, the street finds its own uses for things. I assume that
       | the image was blacklisted, although I will allow for the somewhat
       | baffling concept of a highly-specialized scrotal matching neural-
       | net that overreached a bit or a byte on species, genus, family,
       | and order.
        
         | judge2020 wrote:
         | AFAIK Discord's NSFW filter is not a perceptual hash nor uses
         | the NCMEC database (although that might indeed be in the
         | pipeline elsewhere) but instead uses a ML classifier (I'm
         | certain it doesn't use perceptual hashes as Discord doesn't
         | have a catalogue of NSFW image hashes to compare against). I've
         | guessed it's either open_nsfw[0] or Google's Cloud Vision since
         | the rest of Discord's infrastructure uses Google Cloud VMs.
         | There's a web demo available of this api[1], Discord probably
         | pulls the safe search classifications for determining NSFW.
         | 
         | 0: https://github.com/yahoo/open_nsfw
         | 
         | 1: https://cloud.google.com/vision#section-2
        
         | noduerme wrote:
         | I had to go search for that image. Love it.
         | 
         | >> in the Gibsonian sense
         | 
         | Nice turn of phrase. Can't wait to see what the street's use
         | cases are going to be for this wonderful new spyware. Something
         | nasty, no doubt.
        
         | a_t48 wrote:
         | Adding your friend as a "friend" on discord should disable the
         | filter.
        
           | J_tt wrote:
           | Each user can adjust the settings for how incoming images are
           | filtered, one of the options disables it for friends.
        
       | ttul wrote:
       | Apple would not be so naive as to roll out a solution to child
       | abuse images that has a high false positive rate. They do test
       | things prior to release...
        
         | bjt wrote:
         | I'm guessing you don't remember all the errors in the initial
         | launch of Apple Maps.
        
         | smlss_sftwr wrote:
         | ah yes, from the same company that shipped this:
         | https://medium.com/hackernoon/new-macos-high-sierra-vulnerab...
         | 
         | and this:
         | https://www.theverge.com/2017/11/6/16611756/ios-11-bug-lette...
        
         | celeritascelery wrote:
         | Test it... how exactly? This is detecting illegal material that
         | they can't use to test against.
        
           | bryanrasmussen wrote:
           | Not knowing anything about it but I suppose various
           | governmental agencies maintain corpora of nasty stuff and
           | that you can say to them - hey we want to roll out anti-nasty
           | stuff functionality in our service therefore we need access
           | to corpora to test at which point there is probably a pretty
           | involved process that requires governmental access also to
           | make sure things work and are not misused otherwise -
           | 
           | how does anyone ever actually fight the nasty stuff? This
           | problem structure of how do I catch examples of A if examples
           | of A are illegal must apply in many places and ways.
        
             | vineyardmike wrote:
             | Test it against innocent data sets, then in prod swap it
             | for the opaque gov db of nasty stuff and hope the gov was
             | honest about what is in it :)
             | 
             | They don't need to train a model to detect the actual data
             | set. They need to train a model to follow a pre-defined
             | algo
        
               | [deleted]
        
           | zimpenfish wrote:
           | > This is detecting illegal material that they can't use to
           | test against.
           | 
           | But they can because they're matching the hashes to the ones
           | provided by NCMEC, not directly against CSAM itself (which
           | presumably stays under some kind of lock and key at NCMEC.)
           | 
           | Same as you can test whether you get false positives against
           | a bunch of MD5 hashes that Fred provides without knowing the
           | contents of his documents.
        
           | ben_w wrote:
           | While I don't have any inside knowledge at all, I would
           | expect a company as big as Apple to be able to ask law
           | enforcement to run Apple's algorithm on data sets Apple
           | themselves don't have access to and report the result.
           | 
           | No idea if they did (or will), but I do expect it's possible.
        
             | zimpenfish wrote:
             | > ask law enforcement to run Apple's algorithm on data sets
             | Apple themselves don't have access to
             | 
             | Sounds like that's what they did since they say they're
             | matching against hashes provided by NCMEC generated from
             | their 200k CSAM corpus.
             | 
             | [edit: Ah, in the PDF someone else linked, "First, Apple
             | receives the NeuralHashes corresponding to known CSAM from
             | the above child-safety organizations."]
        
           | IfOnlyYouKnew wrote:
           | They want to avoid false powitives, so you would test for
           | that by running it over innocuous photos, anyway.
        
       | madmax96 wrote:
       | Why not make it so that I can see flagged images in my library?
       | It would give me a lot more confidence that my photos stay
       | private.
        
       | [deleted]
        
       | jiggawatts wrote:
       | The world in the 1900s:
       | 
       | Librarians: "It is unthinkable that we would ever share a
       | patron's borrowing history!"
       | 
       | Post office employees: "Letters are private, only those commie
       | countries open the mail their citizens send!"
       | 
       | Police officers: "A search warrant from a Judge or probable cause
       | is required before we can search a premises or tap a single,
       | specific phone line!"
       | 
       | The census: "Do you agree to share the full details of your
       | record after 99 years have elapsed?"
       | 
       | The world in the 2000s:
       | 
       | FAANGs: "We know _everything_ about you. Where you go. What you
       | buy. What you read. What you say and to whom. _What specific type
       | of taboo pornography you prefer._ We 'll happily share it with
       | used car salesmen and the hucksters that sell WiFi radiation
       | blockers and healing magnets. Also: Cambridge Analytica, the
       | government, foreign governments, and anyone who asks and can pony
       | up the cash, really. Shh now, I have a quarterly earnings report
       | to finish."
       | 
       | Device manufacturers: "We'll rifle through your photos on a
       | weekly basis, just to see if you've got some banned propaganda.
       | Did I say propaganda? I meant child porn, that's harder to argue
       | with. The algorithm is the same though, and just how the
       | Australian government put uncomfortable information leaks onto
       | the banned CP list, so will your government. No, you can't check
       | the list! You'll have to just trust us."
       | 
       | Search engines: "Tiananmen Square is located in Beijing China.
       | Here's a cute tourist photo. No further information available."
       | 
       | Online Maps: "Tibet (China). Soon: Taiwan (China)."
       | 
       | Media distributors: "We'll go into your home, rifle through your
       | albums, and take the ones we've stopped selling. Oh, not
       | _physically_ of course. No-no-no-no, nothing so barbaric! We 'll
       | simply remotely instruct your device to delete anything we no
       | longer want you to watch or listen to. Even if you bought it from
       | somewhere else and uploaded it yourself. It _matches a hash_ ,
       | you see? It's got to go!"
       | 
       | Governments: "Scan a barcode so that we can keep a record of your
       | every movement, for public health reasons. Sure, Google and Apple
       | developed a secure, privacy-preserving method to track exposures.
       | We prefer to use our method instead. Did we forget to mention the
       | data retention period? Don't worry about that. Just assume...
       | indefinite."
        
         | bcrosby95 wrote:
         | Your view of the 1900s is very idyllic.
        
       | IfOnlyYouKnew wrote:
       | Apple's documents said they require multiple hits before anything
       | happens, as the article notes. They can (and have) adjusted that
       | number to any desired balance of false positive to negatives.
       | 
       | How can they say it's 1 in a trillion? You test the algorithm on
       | a bunch of random negatives, see how many positives you get, and
       | do one division and one multiplication. This isn't rocket
       | science.
       | 
       | So, while there are many arguments against this program, this
       | isn't it. It's also somewhat strange to believe the idea of
       | collisions in hashes of far smaller size than the images they are
       | run on somehow escaped Apple and/or really anyone mildly
       | competent.
        
         | fogof wrote:
         | I was unhappy to find this comment so far down and even
         | unhappier to see it downvoted. I'm not a fan of the decrease in
         | privacy Apple is creating with this move but I think this forum
         | has gotten its feelings for Apple caught up with its response
         | to a completely valid criticism of an anti-Apple article.
         | 
         | To explain things even further, let's say that the perceptual
         | algorithm makes a false positive 1% of the time. That is, 1 in
         | every 100 completely normal pictures are incorrectly matched
         | with some picture in the child pornography database. There's no
         | reason to think (at least none springs to mind, happy to hear
         | suggestions) that a false positive in one image will make it
         | any more likely to see a false positive in another image. Thus,
         | if you have a phone with 1000 pictures on it, and it takes 40
         | trigger a match, there's less than a 1 in a trillion
         | probability that this would happen if the pictures are all
         | normal.
        
           | IfOnlyYouKnew wrote:
           | At this point, the COVID vaccines seem to barely have
           | majority support on HN, and "cancel culture" would win any
           | survey on our times' top problems, beating "women inventing
           | stories of rape' and "the black guy mentioning something
           | borderline political at work, just because he's paid 5/8th as
           | much as others".
           | 
           | An inability to follow even the most elementary argument from
           | statistics isn't really surprising. Although I can't quite
           | say if it's actual inability, or follows from the fact that
           | it supports the wrong outcome.
        
         | bt1a wrote:
         | That would not be a good way to arrive at an accurate estimate.
         | Would you not need dozens of trillions of photos to begin with
         | in order to get an accurate estimate when the occurrence rate
         | is so small?
        
           | KarlKemp wrote:
           | What? No...
           | 
           | Or, more accurately: if you need "dozens of trillions" that
           | implies a false positive rate so low, it's practically of no
           | concern.
           | 
           | You'd want to look up the poisson distribution for this. But,
           | to get at this intuitively: say you have a bunch of eggs,
           | some of which may be spoiled. How many would you have to
           | crack open, to get a meaningful idea of how many are still
           | fine, and how many are not?
           | 
           | The absolute number depends on the fraction that are off. But
           | independent of that, you'd usually start trusting your sample
           | when you've seen 5 to 10 spoiled ones.
           | 
           | So Apple runs the hash algorithm on random photos. They find
           | 20 false positives in the first ten million. Given that error
           | rate, how many positives would it require for the average
           | photo collection of 10,000 to be certain at at 1:a trillion
           | level that it's not just coincidence?
           | 
           | Throw it into, for example,
           | https://keisan.casio.com/exec/system/1180573179 with lambda =
           | 0.2 (you're expecting one false positive for every 50,000 at
           | the error rate we assumed, or 0.2 for 10,000), and n = 10
           | (we've found 10 positives in this photo library) to see the
           | chances of that, 2.35x10^-14, or 2.35 / 100 trillion.
        
       | mrtksn wrote:
       | 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 they will start asking you start saving your
       | country. Depending on your location they will start checking
       | against sins against religion, race, family values, political
       | activities.
       | 
       | 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.
       | 
       | I'm big Apple fanboy, but I'm not going to carry a snitch in my
       | pocket. That's "U2 Album in everyone's iTunes library" blunder
       | level creepy with the only difference that it's actually truly
       | creepy.
       | 
       | In my case, my iPhone is going to be snitching me to Boris and
       | Erdogan, in your case it could be Macron, Bolsonaro, Biden, Trump
       | etc.
       | 
       | That's no go for me, you can decide for yourself.
        
         | gpm wrote:
         | 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.
        
           | efitz wrote:
           | 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.
        
             | gpm wrote:
             | Canning Parler is Apple choosing not to advertise and send
             | you an app they don't like, i.e. it's Apple exercising it's
             | own right to free speech. Agree or disagree with it, it's
             | categorically different from Apple spying on what the files
             | you have are saying (not even to or via Apple) and
             | reporting it to the government.
        
               | wyager wrote:
               | Apple also disallows you from installing things without
               | going through them, so "choosing not to advertise and
               | send" has a lot more significance than your wording
               | implies.
               | 
               | It's not like they have a curated App Store for apps they
               | like; there's literally no other way to add software to
               | the device.
        
               | gpm wrote:
               | Right, but the fallout that prevents you from installing
               | it is an incidental consequence of Apple choosing not to
               | promote it and Apple choosing to use it's monopoly on app
               | distribution as an income channel.
               | 
               | Speech not happening because Apple didn't go out of it's
               | way for it to create a route for it to happen without
               | Apple being involved, isn't really that shocking or
               | similar to Apple scanning private files. (Apple being
               | allowed to prevent you from installing what you want on
               | your phone is shocking from an anti-trust perspective,
               | but not from a speech perspective).
        
           | esyir wrote:
           | >but there is still a very strong culture of free speech
           | 
           | In my opinion, that culture has been rapidly dying, chipped
           | away by a very sizable and growing chunk that doesn't value
           | it at all, seeing it only as a legal technicality to be
           | sidestepped.
        
             | bigyikes wrote:
             | I find this varies greatly depending on location. Living in
             | California, I was convinced of the same. Living in Texas
             | now, I'm more optimistic.
        
               | esyir wrote:
               | I'm not nearly as happy to hear that as you might think.
               | California is currently the heart of power of the US tech
               | industry, which means they hold outsized power over the
               | rest of the US and the world. That means illiberal values
               | growing there are going to have similarly outsized
               | effects
        
               | goldenkey wrote:
               | I think you mean liberal values. The paradox of the left
               | includes censorship, gun control, etc..
        
               | colordrops wrote:
               | I think your mean liberal as in tribe, and gp means
               | liberal as in values.
        
               | jacoblambda wrote:
               | FYI Illiberal values aka non-liberal values (clarifying
               | because the I is hard to read) use the word liberal in
               | the traditional sense.
               | 
               | Liberal values are liberty/freedom, consent of the
               | governed, and equality before the law. All other liberal
               | values build off of these three as a base. This implies
               | that Non-liberal (or illiberal) values are the opposition
               | of liberal values through censorship, gun control, etc
               | like you mentioned.
               | 
               | Liberals in the modern US political sense refers to Neo-
               | liberals. Neo-liberal and liberal are two very different
               | things which is why the term liberal value doesn't
               | necessarily correspond to neo-liberal beliefs.
               | 
               | Additionally, "the left" by and large does not support
               | neo-liberalism. "The left" is violently against the
               | aforementioned censorship, gun control, etc. Reading any
               | socialist or communist literature will make this
               | abundantly clear.
               | 
               | Examples:
               | 
               | - George Orwell on the Right to bear Arms: "The
               | totalitarian states can do great things, but there is one
               | thing they cannot do, they cannot give the factory worker
               | a rifle and tell him to take it home and keep it in his
               | bedroom. That rifle hanging on the wall of the working-
               | class flat or labourer's cottage is the symbol of
               | democracy. It is our job to see it stays there."
               | 
               | - George Orwell on Freedom of Speech: "Threats to freedom
               | of speech, writing and action, though often trivial in
               | isolation, are cumulative in their effect and, unless
               | checked, lead to a general disrespect for the rights of
               | the citizen."
               | 
               | - Karl Marx on the Right to bear Arms: "Under no pretext
               | should arms and ammunition be surrendered; any attempt to
               | disarm the workers must be frustrated, by force if
               | necessary"
               | 
               | - Karl Marx on Freedom of Speech: "The absence of freedom
               | of the press makes all other freedoms illusory. One form
               | of freedom governs another just as one limb of the body
               | does another. Whenever a particular freedom is put in
               | question, freedom in general is put in question"
               | 
               | - Karl Marx on Freedom of Speech: "Censorship has
               | outlived its time; where it still exists, it will be
               | regarded as a hateful constraint which prohibits what is
               | openly said from being written"
               | 
               | - Karl Marx on Freedom of Speech: "You cannot enjoy the
               | advantages of a free press without putting up with its
               | inconveniences. You cannot pluck the rose without its
               | thorns!"
               | 
               | If you want I can dig up more quotes but those are the
               | ones that were easy to fetch and any more risks turning
               | this into even more of a wall of text.
               | 
               | My point being, your issues with "the left" are
               | misdirected and are better focused towards Neo-liberalism
               | and/or Neo-conservatism. "The left" does and has always
               | been one of the primary guardians of liberal ideology.
               | Hell "the left" is where a significant portion of the
               | liberal ideology that the United States is founded on
               | originated from.
        
               | goldenkey wrote:
               | Those are great but the left in its current form pushes
               | for larger and larger government. I believe that large
               | government is incompatible with freedom. A hammer will
               | always find a nail given enough time for bad actors to
               | exploit the search space.
               | 
               | Marxism prescribes the atrophy of the state:
               | https://en.wikipedia.org/wiki/Withering_away_of_the_state
               | 
               | The left as it stands in its current dominant form, is a
               | hypocrisy of incompatibles.
               | 
               | True liberalism as you describe it, doesn't exist in any
               | first world country. It's been bundled into larger and
               | larger government creep which inevitably tramples on
               | individual rights.
        
               | mrtksn wrote:
               | The confusion seems to arise from Americans calling the
               | democrats "the left". It's like fighting over which brand
               | of chips is the best, Lays or Pringles.
               | 
               | A tip: These are not chips.
        
               | sobriquet9 wrote:
               | Karl Marx quote on the right to keep and bear arms only
               | applies to the proletariat. If you are a programmer and
               | own the means of production (your laptop), you are not
               | proletariat. All socialist and communist countries have
               | strict gun control.
        
               | goldenkey wrote:
               | If you own AWS or GCP or Azure is a better example of
               | owning means of production. A laptop cannot make you
               | enough money to live by means of renting it out.
        
               | [deleted]
        
               | bccdee wrote:
               | Proletarians make a living off of wage labour. The
               | Bourgeois make enough to live on off of investments in
               | capital.
               | 
               | Owning a laptop is perhaps a very tiny investment in
               | capital, arguably, but it certainly won't provide enough
               | passive income to replace your job.
        
               | mannerheim wrote:
               | All the experience the Chinese people have accumulated
               | through several decades teaches us to enforce the
               | people's democratic dictatorship, that is, to deprive the
               | reactionaries of the right to speak and let the people
               | alone have that right.
               | 
               | - Mao Zedong
        
           | feanaro wrote:
           | > but there is still a very strong culture of free speech,
           | particularly political speech.
           | 
           | Free speech didn't seem so important recently when the SJW
           | crowd started mandating to censor certain words because
           | they're offensive.
        
             | wpietri wrote:
             | Free speech doesn't mean the speaker is immune from
             | criticism or social consequences. If I call you a bunch of
             | offensive names here, I'll get downvoted for sure. The
             | comment might be hidden from most. I might get shadowbanned
             | or totally banned, too.
             | 
             | That was true of private spaces long before HN existed. If
             | you're a jerk at a party, you might get thrown out. I'm
             | sure that's been true as long as there have been parties.
             | 
             | The only thing "the SJW crowd" has changed is _which_ words
             | are now seen as offensive.
        
               | feanaro wrote:
               | > The only thing "the SJW crowd" has changed is which
               | words are now seen as offensive.
               | 
               | Well, _that_ , and also bullying thousands of well-
               | meaning projects into doing silly renamings they didn't
               | want or need to spend energy on. Introducing thousands of
               | silly little bugs and problems downstream, wasting
               | thousands of productive hours.
        
           | l33t2328 wrote:
           | I don't see how the US is becoming "less stable" in any
           | meaningful sense. Can you elaborate?
        
             | gpm wrote:
             | 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.
        
               | l33t2328 wrote:
               | Calling what Trump did an attempted coup is hyperbole
               | beyond belief.
               | 
               | The support for packing the supreme court is mostly at
               | the fringes of the party, and there's always been some
               | support.
               | 
               | There are almost no laws with any kind of support that
               | have transparent goals of suppressing voters. Election
               | security laws are clearly necessary after the doubt the
               | democrats had it was secure in 2016, and the doubts the
               | republicans had in 2020.
               | 
               | Laws absolving drivers of hitting protesters don't exist.
               | Laws absolving drivers of driving through violent rioters
               | do, and such laws are necessary. I saw a a riot with my
               | own eyes where a half dozen cars were flipped and
               | destroyed, and anyone trying to drive through the
               | intersection had people jumping on their car and smashing
               | the windows. These laws are good.
        
             | jeromegv wrote:
             | An attack on the capitol on January 6. A former president
             | that spent weeks trying to delegitimize the election,
             | trying to get people fired when they were just following
             | the process to ratify the election, etc.
        
               | l33t2328 wrote:
               | I'm struggling to see how a few people shitting on
               | Pelosi's desk and stealing a podium really changed the
               | nature of American stability.
        
           | dannyw wrote:
           | Did you literally not see a former president effectively get
           | silenced in the public sphere by 3 corporations?
           | 
           | How can you seriously believe that these corporations (who
           | are not subject to the first amendment, and cannot be
           | challenged in court) won't extend and abuse this technology
           | to tackle "domestic extremism" but broadly covering political
           | views?
        
             | macintux wrote:
             | > a former president effectively get silenced in the public
             | sphere
             | 
             | It's laughable that a man who can call a press conference
             | at a moment's notice and get news coverage for anything he
             | says can be "silenced" because private companies no longer
             | choose to promote his garbage.
        
               | bzha wrote:
               | This is akin to saying rich people have lots of money, so
               | why not steal from them.
        
               | andy_ppp wrote:
               | Well, I prefer to think of this as redistribution rather
               | than theft. When the government pass laws to tax rich
               | people more I think that's good!
        
               | Decker87 wrote:
               | He's been completely silenced. If you don't believe me,
               | you can hear it from him next week when he's on the
               | largest news network talking about being silenced.
        
               | visarga wrote:
               | Yes, because we all trust him at this point /s
        
               | l33t2328 wrote:
               | You don't have to believe him; it's clear on the face of
               | it. Trump often spoke directly to the voters on Twitter
               | and Youtube. That's gone now.
        
               | wpietri wrote:
               | Trump can still speak directly to the voters who are
               | interested. It turns out not very many are interested.
               | E.g.: https://www.cnbc.com/2021/06/02/trump-blog-page-
               | shuts-down-f...
               | 
               | Even Fox has stopped running his events:
               | https://deadline.com/2021/06/donald-trump-rally-networks-
               | ski...
               | 
               | The largest pro-Trump network has seen major declines in
               | ratings: https://www.thewrap.com/newsmax-fox-news-six-
               | months-ratings/
        
               | gpm wrote:
               | I'm pretty sure the person you are replying to was being
               | sarcastic, "he's so silenced that he can tell you about
               | it".
        
             | wpietri wrote:
             | Those companies can definitely be challenged in courts. But
             | they also have rights, including things like freedom of
             | speech and freedom of association, which is why they win
             | when challenged on this. Why do you think a former
             | president and claimed billionaire should have special
             | rights to their property?
        
         | dylan604 wrote:
         | >but I'm not going to carry a snitch in my pocket.
         | 
         | I wonder how this will hold up against 5th ammendment (in the
         | US) covering self-incrimination?
        
           | ssklash wrote:
           | I assume the third party doctrine makes it so that the 5th
           | amendment doesn't apply here.
        
             | dylan604 wrote:
             | "The third-party doctrine is a United States legal doctrine
             | that holds that people who voluntarily give information to
             | third parties--such as banks, phone companies, internet
             | service providers, and e-mail servers--have "no reasonable
             | expectation of privacy." A lack of privacy protection
             | allows the United States government to obtain information
             | from third parties without a legal warrant and without
             | otherwise complying with the Fourth Amendment prohibition
             | against search and seizure without probable cause and a
             | judicial search warrant." --wiki
             | 
             | Okay, but the users of said 3rd party are doing it under
             | the assumption that it is encrypted on the 3rd party's
             | system in a way that they cannot gain access to it. The
             | unencrypted data is not what the user is giving to iCloud.
             | So technically, the data this scan is providing to the
             | authorities is not the same data that the user is giving to
             | the 3rd parties.
             | 
             | Definitely some wiggle room on both sides for some well
             | versed lawyers to chew up some billing hours.
        
         | cyanydeez wrote:
         | you have to realize though that the panopticon is limited only
         | by the ability of "authority" to sift through it for whatever
         | it is it is looking for.
         | 
         | as this article points out, the positive matches will still
         | need an observe to confirm what it is and is not.
         | 
         | lastly, the very reason you have this device exposes you to the
         | reality of either accepting a government that regulates these
         | corporate overreaches or accepting private ownership thats
         | profit motive is deeply personal.
         | 
         | you basically have to reverse society or learn to be a hermit,
         | or more realistically, buy into a improved democratic construct
         | that opts into transparent regulation.
         | 
         | but it sounds more like you want to live in a split brained
         | world where your paranoia and antigovernment stance invites
         | dark corporste policies to sell you out anyway
        
         | baggy_trough wrote:
         | Totally agree. This is very sinister indeed. Horrible idea,
         | Apple.
        
           | zionic wrote:
           | So what are we going to _do_ about it?
           | 
           | I have a large user base on iOS. Considering a blackout
           | protest.
        
             | Blammar wrote:
             | Write an iCloud photo frontend that uploads only encrypted
             | images to iCloud and decrypts on your phone only?
        
               | p2t2p wrote:
               | Won't help, the detection of on your phone now. I wonder
               | if one can have a local VPN with a profile installed
               | which could MITM iCloud upload process and take those
               | matching envelops out.
               | 
               | But in the end of the day the only robust way to
               | communicate privately is good old Linux with good old
               | mutt with good old PGP
        
             | mrtksn wrote:
             | IMHO, Unless everything being E2E encrypted becomes the law
             | we can't do anything about it because that's not Apple's
             | initiative but comes from people whose job is to know
             | things and they cannot resist keeping their hands out of
             | these data collecting devices. They promise politicians
             | that all the troubles will go away if we do that.
             | 
             | Child pornography, Terrorism? Solve it the old way.
             | 
             | I don't know why citizens are obligated to make their jobs
             | easier.
             | 
             | We survived the times when phone calls were not moderated,
             | we survived the times when signal intelligence was not a
             | thing.
        
               | munk-a wrote:
               | Unless I missed a big part of this story Apple isn't
               | being compelled by a court to comply - so if the presence
               | of this tech causes a larger PR stink than publicly
               | backing out of the rollout then Apple will read the
               | writing on the wall.
               | 
               | Public and political pressure is definitely an issue -
               | but it's still soft-pressure so applying more pressure in
               | the other direction will be compelling to Apple.
        
               | mrtksn wrote:
               | Apple was supposed to E2E encrypt everything. Then
               | reports surfaced that FBI complained and they stopped.
               | 
               | The are speculations about this being Apple's solution to
               | government demands so that they can continue migrating to
               | E2E.
               | 
               | They are trying a solution where the device reports you
               | to the authorities so that Apple gets out of the business
               | of knowing your data.
        
               | mrtksn wrote:
               | Just to clarify, this "on device content control" defies
               | all the benefits of the E2E encryption because it is "at
               | the end". It will enable Apple to implement E2E and give
               | the authorities a channel to program the devices to
               | report users in possession of content deemed unacceptable
               | by the authorities.
        
               | HWR_14 wrote:
               | > Solve it the old way.
               | 
               | In fairness, in the "old way" it was impossible for two
               | random people to communicate in real-time between
               | continents without the ability of authorities to
               | observe/break it.
               | 
               | Privacy and security is quite important, but let's not
               | lose track of the fact that there are many tools
               | authorities have lost in the past few decades. In WWII
               | major powers weren't able to have the same security of
               | military communications as an idiot can today. And that's
               | relative to codebreaking technology.
               | 
               | If I had a good solution, I'd tell you.
        
               | mrtksn wrote:
               | The difference is that previously you had to be targeted
               | and intercepted. Thinking that someone is listening was
               | something that paranoid people would do.
               | 
               | Now your device is actually watching you and reporting
               | you. Today only for child porn but there's no technical
               | reason of it not being extended to anything.
        
               | HWR_14 wrote:
               | > The difference is that previously you had to be
               | targeted and intercepted
               | 
               | This is also true, to some degree. I believe all calls to
               | the USSR were monitored, for instance. But the dragnet is
               | thrown much further these days.
        
               | pomian wrote:
               | That was a very well put together comment. Good one.
        
         | asimpletune wrote:
         | 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.
        
           | voidnullnil wrote:
           | Companies change. The sad part is, there is no next company
           | to move to.
        
           | jeromegv wrote:
           | 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?
        
             | zekrioca wrote:
             | You answered your own question and still don't get it.
        
               | wpietri wrote:
               | Then perhaps you could explain it? I also don't
               | understand why server-side versus client-side CSAM
               | inspection makes a big difference.
        
               | wizzwizz4 wrote:
               | If I ask you to store my images, and you therefore have
               | access to the images, you can scan them for stuff using
               | _your computers_. The scope is limited to the images I
               | ask you to store, and your computers are doing what you
               | ask them to.
               | 
               | If you reprogram my computer to scan my images _stored on
               | my computer_ ... different thing entirely. I don't have a
               | problem with checking them for child abuse (in fact, I'd
               | give up quite a bit of freedom to stop that), but nothing
               | about this tech makes it specific to child abuse. I don't
               | want my computer ratting me out for stuff that I have the
               | right (or, possibly, the _obligation_ ) to be doing, just
               | because the powerful don't want me doing it. At the
               | _moment_ , it doesn't.
               | 
               | This tech makes Apple-controlled computers untrustworthy.
               | It will probably lead to the deaths of political
               | dissidents; these things always do. Is that worth it?
        
               | acdha wrote:
               | So far, this is only for iCloud photos so currently it
               | seems highly similar to what we have now except that it's
               | on the device and could be done with end to end
               | encryption, unlike the current approach.
               | 
               | For me, the big concern is how it could be expanded. This
               | is a real and valid problem but it's certainly not hard
               | to imagine a government insisting it needs to be expanded
               | to cover all photos, even for people not using iCloud,
               | and we'd like you to add these signatures from some
               | images we can't show you. Once the infrastructure is
               | there it's a lot easier to do that.
        
               | wizzwizz4 wrote:
               | Yes. If Apple takes the "we're not going to" stance, then
               | this _could_ be okay... but they 've been doing that less
               | and less, and they only ever really did that in the US /
               | Australia. Apple just isn't trustworthy enough.
        
               | acdha wrote:
               | Also that since the system is opaque by design it'd be
               | really hard to tell if details changes. Technically I
               | understand why that's the case but it makes the question
               | of trust really hard.
        
           | echelon wrote:
           | 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.
        
         | Klonoar wrote:
         | 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 regardless of whether it's
         | done on or off device. iCloud has _always_ been a known vector
         | for authorities to peek.
         | 
         | >I'm big Apple fanboy, but I'm not going to carry a snitch in
         | my pocket.
         | 
         | If you use iCloud, you arguably already do.
        
           | Renaud wrote:
           | What has changed is the inclusion of spyware technology on
           | the device that can be weaponised to basically report on
           | anything.
           | 
           | Today it's only geared toward iCloud and CSAM. How many lines
           | of codes do you think it will take before it scans all your
           | local pictures?
           | 
           | How hard do you think it will be for an authoritarian regime
           | like China, that Apple bends over backwards to please, to
           | start including other hashes that are not CSAM?
           | 
           | iCloud is opt-out. They can scan server-side like everyone
           | does. Your device is your device, and it now contains, deeply
           | embedded into it, the ability to perform actions that are not
           | under your control and can silently report you directly to
           | the authorities.
           | 
           | If you don't see a deep change there, I don't know what to
           | say.
           | 
           | I live in a country that is getting more authoritarian by the
           | day, where people are sent to prison (some for life) for
           | criticizing the government, sometime just for chanting or
           | printing a slogan.
           | 
           | This is the kind of crap that makes me extremely angry at
           | Apple. Under the guise of something no-one can genuinely be
           | against (think of the children!), they have now included a
           | pretty generic snitch into your phone and made everyone
           | accept it.
        
             | Klonoar wrote:
             | >What has changed is the inclusion of spyware technology on
             | the device that can be weaponised to basically report on
             | anything.
             | 
             | - You are running a closed source proprietary OS that you
             | cannot verify is not already doing anything.
             | 
             | - This could theoretically already be weaponized (with the
             | existing server-side implementation) by getting someone to
             | download a file to a folder that iCloud automatically syncs
             | from.
             | 
             | >iCloud is opt-out.
             | 
             | Yes, and that's how you opt out of this scanning. It's the
             | same opt-out as before.
             | 
             | >Under the guise of something no-one can genuinely be
             | against (think of the children!) they have now included a
             | pretty generic snitch into your phone and made everyone
             | accept it.
             | 
             | I dunno what to tell you. I think the system as designed is
             | actually pretty smart[1] and more transparent than before.
             | 
             | If you used iCloud before, and you're putting photos up
             | that'd be caught in a hash comparison, you've already got a
             | snitch. Same with any other cloud storage, short of hosting
             | your own.
             | 
             | [1] I reserve the right for actual bona-fide cryptographers
             | to dissect it and set the record straight, mind you.
        
             | wonnage wrote:
             | We gotta stop with the China bogeyman every time a privacy
             | issue comes up. This is a feature designed by an American
             | company for American government surveillance purposes.
             | China is perfectly capable of doing the same surveillance
             | or worse on its own citizens, with or without Apple. China
             | has nothing to do with why American tech is progressively
             | implementing more authoritarian features in a supposedly
             | democratic country.
        
               | dannyw wrote:
               | China is just an example. In Australia, the law allows
               | our executive department to order tech companies to build
               | backdoors for the investigation of any crime punishable
               | by more than 2 years imprisonment.
               | 
               | We actually had the anti terror department arrest a
               | popular, left-leaning YouTube influencer for harassment
               | while physically assaulting his mum (all on video).
               | 
               | That's something that is literally unprecedented in Hong
               | Kong just 3 years ago.
        
               | kelnos wrote:
               | I think it's irresponsible to avoid thinking about how
               | bad actors might use a technology you've developed.
               | 
               | And is it _really_ unfathomable that the US government
               | could use this sort of thing for evil? I mean, wind back
               | the clock to something like the Red Scare. If they had
               | iPhones back then, they totally would have pressured
               | Apple to add hashes for communist imagery, and use that
               | to persecute people (or worse).
               | 
               | (Before anyone brings this up: I do categorically reject
               | the notion of "that was in the past; that couldn't happen
               | today". If you truly believe that, I have a bridge you
               | might be interested in purchasing...)
        
               | bigiain wrote:
               | Ok. How about the Saudi Arabian bogeymen then? Who took
               | Jamal Kashoggi apart with bonesaws as he screamed? Or the
               | Israeli bogeymen who exploited his phone for them? Or the
               | Turkish bogeymen who also a customers of that Israeli
               | phone exploitation company? (Or Facebook who wanted to
               | buy those tools but got turned down, because Facebook is
               | "too far" even for NSO who happily take Saudi and Turkish
               | money?)
               | 
               | There are without doubt enough privacy bogeymen to go
               | around, trying to derail a valid argument over its use of
               | the Chinese as the placeholder bogeyman detracts from the
               | discussion pointlessly.
        
               | wonnage wrote:
               | The point is that all these bogeymen distract from the
               | actual issue, because they make government surveillance
               | sound like something that only happens in other places...
               | We need to wake up and realize it's happening right here
               | at home and has been for decades
        
               | Renaud wrote:
               | No-one was suggesting that China was behind this move.
               | 
               | We're talking about China taking advantage of this
               | integrated technology to increase control over its
               | population through backdoors like these.
               | 
               | China already imposes that all data from Chinese users be
               | located in China and readily accessible and mined by the
               | authorities[1].
               | 
               | Apple is willing to bow to these regimes because it has
               | substantial supply-chain interests there and it sells
               | hundred of millions of devices. A boon to both Apple and
               | the local government.
               | 
               | [1]:https://www.nytimes.com/2021/05/17/technology/apple-
               | china-ce...
        
               | CRConrad wrote:
               | > We're talking about China taking advantage of this
               | integrated technology to increase control over its
               | population through backdoors like these. ... A boon to
               | both Apple and the local government.
               | 
               | But still: Secondary. The main effect of even mentioning
               | it is to deflect attention away from Apple.
        
           | matheusmoreira wrote:
           | What changed is we are not the masters of our technology
           | anymore. If I tell my computer to do something, it should do
           | it without question. It doesn't matter if it's a crime. The
           | computer is supposed to be my tool and obey my commands.
           | 
           | Now what's going to happen instead is the computer will
           | report me to its real masters: corporations, governments. How
           | is this acceptable in any way?
        
           | xuki wrote:
           | 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?
        
             | tialaramex wrote:
             | 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.
        
               | megous wrote:
               | Any of these large services allowing user uploaded
               | content can build such a database in a heartbeat. And
               | with a list of known hashes it can even be automated.
        
             | Klonoar wrote:
             | The questions re: what the CEO would sign off on here don't
             | really matter, as the question could apply whether it's
             | server side or client side.
             | 
             | It _does_ make sense client side if you view it being done
             | server side as a blocker for E2EE on iCloud. There is
             | absolutely no world where Apple could implement that
             | without keeping the ability to say "yes, we're blocking
             | child porn".
        
           | coldtea wrote:
           | > _I would really like people to start answering this: what
           | exactly do you think has changed? e.g,_
           | 
           | Apple has announced they'll be doing this check?
           | 
           | What exactly do you think is the same as before?
           | 
           | > _The exact same outcome can happen regardless of whether it
           | 's done on or off device. iCloud has _always_ been a known
           | vector for authorities to peek._
           | 
           | That's neither here, nor there. It's another thing to peak
           | selectively with a warrant of sorts, than to (a) peak
           | automatically in everybody, (b) with a false-positive-prone
           | technique, especially since the mere accusation on a false
           | match can be disastrous for a person, even if they eventually
           | are proven innocent...
        
             | Klonoar wrote:
             | Responding in a separate comment since I either missed the
             | second half, or it was edited in.
             | 
             | >That's neither here, nor there. It's another thing to peak
             | selectively with a warrant of sorts, than to (a) peak
             | automatically in everybody, (b) with a false-positive-prone
             | technique, especially since the mere accusation on a false
             | match can be disastrous for a person, even if they
             | eventually are proven innocent...
             | 
             | I do not believe that iCloud CSAM server side matching ever
             | required a warrant, and I'm not sure where you've gotten
             | this idea. It quite literally is (a) peak automatically in
             | everybody.
             | 
             | Regarding (b), with this way - thanks to them publishing
             | details on it - there's _more_ transparency than if it was
             | done server side.
             | 
             | >especially since the mere accusation on a false match can
             | be disastrous for a person
             | 
             | As noted elsewhere in this very thread, this can happen
             | whether client or server side. It's not unique in any way,
             | shape or form to what Apple is doing here.
        
               | etchalon wrote:
               | I'm incredibly amused by the number of supposedly deeply
               | technical and informed people on this site who seem to be
               | unaware of CSAM scanning and its existing use on cloud
               | services.
        
             | Klonoar wrote:
             | >What exactly do you think is the same as before?
             | 
             | The same checking when you synced things to iCloud. As has
             | been repeated over and over again, this check happens for
             | iCloud Photos. It's not running arbitrarily.
             | 
             | Your photos were compared before and they're being compared
             | now... if you're using iCloud Photos.
        
               | coldtea wrote:
               | > _The same checking when you synced things to iCloud. As
               | has been repeated over and over again, this check happens
               | for iCloud Photos. It 's not running arbitrarily._
               | 
               | Who said it's running "arbitrarily"? Who said it's not
               | about iCloud Photos?
               | 
               | > _Your photos were compared before and they 're being
               | compared now... if you're using iCloud Photos._
               | 
               | They weren't always compared, they started being compared
               | a few years ago, and they moved to comparing them with a
               | new scheme now.
               | 
               | Both are bad, and not the responsibility of a company
               | selling phones - and also a bad precedent (now it's
               | "think of the children", tomorrow "think of the country",
               | then "think of those with wrong ideas", then "think how
               | much money insurance companies can save" and what have
               | you).
               | 
               | As for your suggestions to just "stop using iCloud
               | Photos", how about we get to enjoy the features we bought
               | our devices for, without stuff we didn't ask for and
               | don't want?
        
               | Klonoar wrote:
               | >Both are bad, and not the responsibility of a company
               | selling phones
               | 
               | Apple is not just a hardware company and there is no
               | obligation for them to host offending contents on their
               | servers - just as Dropbox, Google, and so on would
               | maintain with theirs.
               | 
               | >As for your suggestions to just "stop using iCloud
               | Photos", how about we get to enjoy the features we bought
               | our devices for, without stuff we didn't ask for and
               | don't want?
               | 
               | It's odd to say that a business shouldn't be allowed to
               | police what's on their platform, given we're on a forum
               | explicitly enabling entrepreneurs.
        
               | coldtea wrote:
               | > _It 's odd to say that a business shouldn't be allowed
               | to police what's on their platform, given we're on a
               | forum explicitly enabling entrepreneurs._
               | 
               | It's odd to say that a business should be allowed to
               | police private user content, given we're on a forum with
               | the name "Hacker" on it, built by ex-hackers, and with
               | part of its member's interests heritage not in and
               | "enabling enterpreneurs" but in hacking (in the MIT sense
               | of yore).
        
               | visarga wrote:
               | With many more images, many more false positives. One has
               | as a consequence a message or account being deleted, the
               | other - being reported to the police. Very different!
        
               | jeromegv wrote:
               | They were reporting to the authorities before as well
               | with what was found on iCloud photos.
        
               | macintux wrote:
               | In this case, they're explicitly required by law to
               | report this material if it shows up on their servers.
        
               | coldtea wrote:
               | Well, Jim Crow legislation was also a thing once.
        
               | macintux wrote:
               | This definitely feels like a bad solution provoked by a
               | dubious law; the complaints should be directed at our
               | elected officials, not Apple.
        
               | stetrain wrote:
               | The post office scans your mail through various machines
               | in transit. We accept that when we put the mail in the
               | mailbox.
               | 
               | What if the post office announced they were installing a
               | man with a scanning machine in your home who would scan
               | your letters before they left your house?
               | 
               | It's the same outcome. The same process. Just inside your
               | house instead of out in the mail system. They're exactly
               | the same, except somehow it's not.
        
               | bigiain wrote:
               | > The post office scans your mail through various
               | machines in transit.
               | 
               | That is a totally bogus comparison.
               | 
               | The post office 100% does NOT can the _content_ of every
               | piece mail they handle.
               | 
               | Not even close to the same scenario as Apple/governments
               | being able to continually and silently check your
               | phone/photo library for images on their watch list.
        
               | stetrain wrote:
               | I'm pretty sure lots of mail gets x-rayed, perhaps even
               | more looking for malicious packages or substances.
               | 
               | I agree that data content scanning is more invasive than
               | physical scanning. It was an intentionally simplistic
               | example not meant to defend Apple.
        
               | bigiain wrote:
               | Parcels, maybe. I'd bet it's a tiny percentage though.
               | 
               | I doubt the entire world has enough X-ray machines to
               | scan even a vanishingly small percentage of the envelopes
               | the postal service delivers every day.
        
               | stetrain wrote:
               | Sorry my metaphor wasn't good enough.
        
               | Klonoar wrote:
               | This example changes with regards to emotional weight if
               | you remove "a man" and leave it at just "a scanning
               | machine". There is no human scanning your photos on an
               | iPhone, so let's compares apples to apples here.
               | 
               | If that scanning machine didn't reveal the contents of my
               | mail, and then ensured that it wasn't able to be given
               | out in-transit? Yeah, I'd potentially be fine with it -
               | but I'll leave this answer as a hypothetical since it's
               | all theory anyway.
               | 
               | The point here is that you're _choosing_ to use the mail
               | system and you 're thus _choosing_ to play by those
               | rules. Given that these checks happen _for iCloud_ you
               | 're effectively making the same agreement.
        
               | dannyw wrote:
               | There actually is a man involved: enough similarities and
               | a human will review the photos. Every algorithm,
               | especially perceptual hashing, will have false positives,
               | and at Apple's scale, some people's private and intimate
               | photos will be false positives and be exposed to a man
               | looking at it.
        
               | jeromegv wrote:
               | I think the point of the OP is that it was already the
               | case before when you were using iCloud photos. The scan
               | was server side.
        
               | visarga wrote:
               | > some people's private and intimate photos will be false
               | positives and be exposed to a man looking at it
               | 
               | and deciding who gets reported to police based on their
               | cultural views on nudity
        
               | stetrain wrote:
               | But the barrier between "only happens for iCloud" and
               | "happens for all photos on device" has been reduced to a
               | very small barrier. Before it was the photos actually
               | being sent to a separate server by my choice, now it's
               | Apple saying their on-device tool only runs given
               | criteria X.
               | 
               | And on a second note I think people are allowed to be
               | freshly concerned at the idea of Apple scanning photo
               | libraries given a government-provided hash list, even if
               | it was already happening before now.
        
               | Klonoar wrote:
               | To be clear, I have no qualms about people being
               | concerned. You can find my comments elsewhere on this
               | site that I think people _should_ scrutinize this entire
               | thing.
               | 
               | I'm just very tired of people (not necessarily you)
               | spouting off as if the functionality is _new_. It dilutes
               | an otherwise important conversation. So many of the
               | threads on this site are just people privacy LARPing.
        
               | stetrain wrote:
               | Agreed. I still think there is a distinction, even if
               | only in principle and mostly psychological, between what
               | a company does with my files on their server, and what
               | they do with my files on my device.
               | 
               | Even if the outcome is theoretically the same, the means
               | are different and it feels different.
        
               | visarga wrote:
               | It's not the same because before the hashing was done in
               | the cloud, but now the model is accessible locally, you
               | just need to take pictures. This means it's easier to
               | hack.
               | 
               | If someone discovers a way to reliably generate
               | adversarial images they can send such images to someone
               | else to iSWAT them.
        
               | Klonoar wrote:
               | If your definition of "hack" is "get bob to accept bad
               | file", no, this model is not _easier_ - it 's just
               | _different_.
               | 
               | You could literally piggyback on the directories that
               | Macs use to sync to iCloud Drive, get an image in there,
               | and then it gets scanned by iCloud. This is not some new
               | theoretical attack - and in fact, this would be the
               | "hack" for the new one as well _since it requires iCloud
               | sync to trigger anyway_.
        
           | bigiain wrote:
           | > The opt out of this is to not use iCloud Photos.
           | 
           | Wasn't yesterday's version of this sorry about how Apple is
           | implementing this as a client side service on iPhones?
           | 
           | https://news.ycombinator.com/item?id=28068741
           | 
           | I don't know if the implication there is "don't use the stock
           | Apple camera app and photo albums", or "don't store any
           | images on yours Phone any more" if they are scanning files
           | from other apps for perceptual hash matches as well...
        
             | Klonoar wrote:
             | ...yes, and the client-side check is only run before
             | syncing to iCloud Photos, which is basically just shifting
             | the hash check from before upload (client side) to after
             | upload (server side).
        
               | aix1 wrote:
               | Thanks for this clarification. This, I think, is an
               | important aspect that seems to often get overlooked.
               | 
               | Apple's explanation:
               | 
               | <quote> Before an image is stored in iCloud Photos, an
               | on-device matching process is performed for that image
               | against the known CSAM hashes. This matching process is
               | powered by a cryptographic technology called private set
               | intersection, which determines if there is a match
               | without revealing the result. The device creates a
               | cryptographic safety voucher that encodes the match
               | result along with additional encrypted data about the
               | image. This voucher is uploaded to iCloud Photos along
               | with the image.
               | 
               | Using another technology called threshold secret sharing,
               | the system ensures the contents of the safety vouchers
               | cannot be interpreted by Apple unless the iCloud Photos
               | account crosses a threshold of known CSAM content. The
               | threshold is set to provide an extremely high level of
               | accuracy and ensures less than a one in one trillion
               | chance per year of incorrectly flagging a given account.
               | </quote>
               | 
               | https://www.apple.com/child-safety/
        
           | foerbert wrote:
           | I think one of the major factors that changes how people
           | perceive this is that it's happen on their own device. If you
           | upload a thing to a server and the server does something... I
           | mean sure. You gave a thing to somebody else, and they did
           | something with it. That's a very understandable and largely
           | accepted situation.
           | 
           | This is different. This is your own device doing that thing,
           | out of your control. Alright sure, it's doing the same thing
           | as the other server did and under the same circumstances* so
           | maybe functionally nothing has changed. But the philosophical
           | difference is quite huge between somebody else's server
           | watching over what you upload and your own device doing it.
           | 
           | I'm struggling to come up with a good analogy. The closest I
           | can really think of is the difference between a reasonably
           | trusted work friend and your own family member reporting you
           | to the authorities for suspicious behavior in your workplace
           | and home respectively. The end result is the same, but I
           | suspect few people would feel the same about those
           | situations.
           | 
           | * There is no inherent limitation for your own device to only
           | be able to check photos you upload to iCloud. There is
           | however such a limitation for the iCloud servers. A very
           | reasonably and potentially functional difference is the
           | ability for this surveillance to be easily expanded beyond
           | iCloud uploads in the future.
        
       | drzoltar wrote:
       | The other issue with these hashes is non-robustness to
       | adversarial attacks. Simply rotating the image by a few degrees,
       | or slightly translating/shearing it will move the hash well
       | outside the threshold. The only way to combat this would be to
       | use a face bounding box algorithm to somehow manually realign the
       | image.
        
         | foobarrio wrote:
         | In my admittedly limited experience in image hashing, typically
         | you extract some basic feature and transform the image before
         | hashing (eg darkest corner in the upper left or look for
         | verticals/horizontals and align). You also take multiple hashes
         | of the images to handle various crops, black and white vs
         | color. This increases robustness a bit but overall yea you can
         | always transform the image in such a way to come up with a
         | different enough hash. One thing that would be hard to catch is
         | if you do something like a swirl and then the consumers of that
         | content will use a plugin or something to "deswirl" the image.
         | 
         | There's also something like the Scale Invariant Feature
         | Transform that would protect against all affine transformations
         | (scale, rotate, translate, skew).
         | 
         | I believe one thing that's done is whenever any CP is found,
         | the hashes of all images in the "collection" is added to the DB
         | whether or not they actually contain abuse. So if there are any
         | common transforms of existing images then those also now have
         | their hashes added to the db. The idea being that a high
         | percent of hits from even the benign hashes means the presence
         | of the same "collection".
        
           | megous wrote:
           | Huh, or you can just use encryption if you'll be using some
           | SW based transformation anyway.
        
       | lancemurdock wrote:
       | I am going to give this lineageOS on an android device a shot.
       | This is one of the most egregious things Apple has ever done
        
       | ris wrote:
       | I agree with the article in general except part of the final
       | conclusion
       | 
       | > The simple fact that image data is reduced to a small number of
       | bits leads to collisions and therefore false positives
       | 
       | Our experience with regular hashes suggests this is not the
       | underlying problem. SHA256 hashes have 256 bits and still there
       | are _no known_ collisions, even with people deliberately trying
       | to find them. SHA-1 only has only 160 bits to play with and it 's
       | still hard enough to find collisions. MD5 is easier to find
       | collisions but at 128 bits, still people don't come across them
       | by chance.
       | 
       | I think the actual issue is that perceptual hashes tend to be
       | used with this "nearest neighbour" comparison scheme which is
       | clearly needed to compensate for the inexactness of the whole
       | problem.
        
         | dogma1138 wrote:
         | This isn't due to the entropy of the hash but due to the
         | entropy of the source data.
         | 
         | These algos work by limiting the color space of the photo,
         | usually to only black and white (not even grey scale) resizing
         | it to a fraction of its original size and then chopping it into
         | tiles using a fixed size grid.
         | 
         | This increases the chances of collisions greatly because photos
         | with a similar composition are likely to match on a sufficient
         | number of tiles to flag the photo as a match.
         | 
         | This is why the women image was matched to the butterfly image,
         | if you turn the image to B&W resize it to something like
         | 256x256 pixels and divide it into a grid of say 16 tiles all of
         | a sudden a lot of these tiles can match.
        
         | giantrobot wrote:
         | Perceptual hashes don't involve diffusion and confusion steps
         | like cryptographic hashes. Perceptual hashes _don 't_ want
         | decorrelation like cryptographic hashes. In fact they want
         | similar but not identical images to end up with similar hash
         | values.
        
       | alkonaut wrote:
       | The key here is scale. If the only trigger for action is having
       | (say) _a few hundred_ matching images, or a dozen from the same
       | known set of offending pictures, then I can see how apples "one
       | in a trillion" claim would work.
       | 
       | Also, Apple could ignore images from the device camera - since
       | those will never match.
       | 
       | This is also in stark contrast to the task faced by photo
       | copyright hunters. They don't have the luxury of only focusing on
       | those who handle tens of thousands of copyrighted photos. They
       | need to find individual violations because that's what they are
       | paid to do.
        
       | marcinzm wrote:
       | > an Apple employee will then look at your (flagged) pictures.
       | 
       | Always fun when unknown strangers get to look at your potentially
       | sensitive photos with probably no notice given to you.
        
         | judge2020 wrote:
         | They already do this for photodna-matched iCloud Photos (and
         | Google Photos, Flickr, Imgur, etc), perceptual hashes do not
         | change that.
        
           | version_five wrote:
           | I'm not familiar with iPhone picture storage. Are the
           | pictures automatically sync'ed with cloud storage? I would
           | assume (even if I don't like it) that cloud providers may be
           | scanning my data. But I would not expect anyone to be able to
           | see or scan what is stored on my phone.
           | 
           | Incidentally, I work in computer vision and handle
           | proprietary images. I would be violating client agreements if
           | I let anyone else have access to them. This is a concern I've
           | had in the past e.g. with Office365 (the gold standard in
           | disregarding privacy) that defaults to sending pictures in
           | word documents to Microsoft servers for captioning, etc. I
           | use a Mac now for work, but if somehow this snooping applies
           | to computers as well I can't keep doing so while respecting
           | the privacy of my clients.
           | 
           | I echo the comment on another post, Apple is an entertainment
           | company, I don't know why we all started using their products
           | for business applications.
        
             | Asdrubalini wrote:
             | You can disable automatic backups, this way your photos
             | won't ever be uploaded to iCloud.
        
             | abawany wrote:
             | By default it is enabled. One has to go through Settings to
             | turn off the default iCloud upload, afaik.
        
               | judge2020 wrote:
               | I would imagine most people do with the abysmal 5GB of
               | storage they offer for free and how backups take up all
               | of it.
        
       | starkd wrote:
       | The method Apple is using looks more like a cryptographic hash.
       | That's entirely different (and more secure) than a perceptual
       | hash.
       | 
       | From https://www.apple.com/child-safety/
       | 
       | "Before an image is stored in iCloud Photos, an on-device
       | matching process is performed for that image against the known
       | CSAM hashes. This matching process is powered by a cryptographic
       | technology called private set intersection, which determines if
       | there is a match without revealing the result. The device creates
       | a cryptographic safety voucher that encodes the match result
       | along with additional encrypted data about the image. This
       | voucher is uploaded to iCloud Photos along with the image."
       | 
       | Elsewhere, it does explain the use of neuralhashes which I take
       | to be the perceptual hash part of it.
       | 
       | I did some work on a similar attempt awhile back. I also have a
       | way to store hashes and find similar images. Here's my blog post.
       | I'm currently working on a full site.
       | 
       | http://starkdg.github.io/posts/concise-image-descriptor
        
         | [deleted]
        
         | cvwright wrote:
         | The crypto here is for the private set intersection, not the
         | hash.
         | 
         | So your device has a list of perceptual (non-cryptographic)
         | hashes of its images. Apple has a list of the hashes of known
         | bad images.
         | 
         | The protocol lets them learn which of your hashes are in the
         | "bad" set, without you learning any of the other "bad" hashes,
         | and without Apple learning any of the hashes of your other
         | photos.
        
           | bastawhiz wrote:
           | Well therein lies the problem: perceptual hashes don't
           | produce an exact result. You need to compare something like
           | the hamming distance (as the article mentions) of each hash
           | to decide if it's a match.
           | 
           | Is it possible to perform private set intersection where the
           | comparison is inexact? I.e., if you have two _cryptographic_
           | hashes, private set intersection is well understood. Can you
           | do the same if the hashes are close, but not exactly equal?
           | 
           | If the answer is yes, that could mean you would be able to
           | derive the perceptual hashes of the CSAM, since you're able
           | to find values close to the original and test how far you can
           | drift from it before there's no longer a match.
        
             | cvwright wrote:
             | From what I've read, part of the magic here is that Apple's
             | perceptual hash is an exact hash. Meaning, you don't have
             | to do the Hamming distance thing.
             | 
             | Admittedly, I haven't had a chance to read the original
             | source material yet. It's possible that the person I heard
             | this from was wrong.
        
             | aix1 wrote:
             | Would love to learn more about actual algorithms that could
             | be used to do something like this (private set intersection
             | with approximate matching) if they exist.
        
         | dogma1138 wrote:
         | The cryptography is most likely done at a higher level than the
         | perception comparison and is quite likely done to protect the
         | CSAM hashes than your privacy.
         | 
         | My interpretation of this is that they still use some sort of a
         | perception based matching algorithm they just encrypt the
         | hashes and then use some "zero knowledge proof" when comparing
         | the locally generated hashes against the list, the result of
         | which would be just that X hashes marched but not which X.
         | 
         | This way there would be no way to reverse engineer the CSAM
         | hash list or bypass the process by altering key regions of the
         | image.
        
           | visarga wrote:
           | > the result of which would be just that X hashes marched but
           | not which X
           | 
           | That means you can't prove an incriminating file was not
           | deleted even if you're the victim of a false positive. So
           | they will suspect you and put you through the whole police
           | investigation routine.
        
             | dogma1138 wrote:
             | Not necessarily it just means that you don't know/prove
             | until a certain threshold is reached, in guessing above a
             | specific one that hashes and the photo is then uploaded to
             | Apple for verification and preservation.
        
       | avnigo wrote:
       | > These cases will be manually reviewed. That is, according to
       | Apple, an Apple employee will then look at your (flagged)
       | pictures.
       | 
       | I'm surprised this hasn't gotten enough traction outside of tech
       | news media.
       | 
       | Remember the mass celebrity "hacking" of iCloud accounts a few
       | years ago? I wonder how those celebrities would feel knowing that
       | some of their photos may be falsely flagged and shown to other
       | people. And that we expect those humans to act like robots and
       | not sell or leak the photos, etc.
       | 
       | Again, I'm surprised we haven't seen a far bigger outcry in the
       | general news media about this yet, but I'm glad to see a lot of
       | articles shining light on how easy it is for false positives and
       | hash collisions to occur, especially at the scale of all iCloud
       | photos.
        
         | lliamander wrote:
         | That really alarmed me. I don't think a hosting provider like
         | Apple should have a right to access private pictures,
         | especially just to enforce copyright.
         | 
         | Edit: I see now it's not about copyright, but still very
         | disturbing.
        
         | judge2020 wrote:
         | They wouldn't be falsely flagged. It doesn't detect naked
         | photos, it detects photos matching real confirmed CSAM based on
         | the NCMEC's database.
        
           | auggierose wrote:
           | If that would always work, a manual review would not be
           | necessary. Just send the flagged photo and its owner straight
           | to the police.
        
           | josefx wrote:
           | Hashes, no false matches, pick one.
        
           | wongarsu wrote:
           | It will flag pictures that match a perceptual hash of
           | pictures of child abuse. Now what legal kinds of pictures are
           | most similar in composition, color, etc. to those offending
           | pictures? What kinds of pictures would be hardest to
           | distinguish from offending pictures if you were given only
           | 16x16 thumbnails?
           | 
           | I'm going to bet the algorithm will struggle the most with
           | exactly the pictures you don't want reviewers or the public
           | to see.
        
           | avnigo wrote:
           | The article posted, as well as many others we've seen
           | recently, demonstrate that collisions are possible, and most
           | likely inevitable with the number of photos to be scanned for
           | iCloud, and Apple recognizes this themselves.
           | 
           | It doesn't necessarily mean that all flagged photos would be
           | of explicit content, but even if it's not, is Apple telling
           | us that we should have no expectation of privacy for any
           | photos uploaded to iCloud, after running so many marketing
           | campaigns on privacy? The on-device scanning is also under
           | the guise of privacy too, so they wouldn't have to decrypt
           | the photos on their iCloud servers with the keys they hold
           | (and also save some processing power, maybe).
        
             | spacedcowboy wrote:
             | Apple already use the same algorithm on photos in email,
             | because email is unencrypted. Last year Apple reported 265
             | cases according to the NYT. Facebook reported 20.3 million.
             | 
             | Devolving the job to the phone is a step to making things
             | more private, not less. Apple don't need to look at the
             | photos on the server (and all cloud companies in the US are
             | required to inspect photos for CSAM) if it can be done on
             | the phone, removing one more roadblock for why end-to-end
             | encryption hasn't happened yet.
        
               | nullc wrote:
               | > all cloud companies in the US are required to inspect
               | photos for CSAM)
               | 
               | This is extremely disingenuous. If their devices uploaded
               | content with end to end encryption there would be no
               | matches for CSAM.
               | 
               | If they were required to search your materials generally,
               | then they would be effectively deputized-- acting on
               | behalf of the government-- and your forth amendment
               | protection against unlawful search would be would
               | extended to their activity. Instead we find that the both
               | cloud providers and the government have argued and the
               | courts have affirmed the opposite:
               | 
               | In US v. Miller (2017)
               | 
               | > Companies like Google have business reasons to make
               | these efforts to remove child pornography from their
               | systems. As a Google representative noted, "[i]f our
               | product is associated with being a haven for abusive
               | content and conduct, users will stop using our services."
               | McGoff Decl., R.33-1, PageID#161.
               | 
               | > Did Google act under compulsion? Even if a private
               | party does not perform a public function, the party's
               | action might qualify as a government act if the
               | government "has exercised coercive power or has provided
               | such significant encouragement, either overt or covert,
               | that the choice must in law be deemed to be that of the"
               | government. [...] Miller has not shown that Google's
               | hash-value matching falls on the "compulsion" side of
               | this line. He cites no law that compels or encourages
               | Google to operate its "product abuse detection system" to
               | scan for hash-value matches. Federal law disclaims such a
               | mandate. It says that providers need not "monitor the
               | content of any [customer] communication" or
               | "affirmatively search, screen, or scan" files. 18 U.S.C.
               | SS 2258A(f). Nor does Miller identify anything like the
               | government "encouragement" that the Court found
               | sufficient to turn a railroad's drug and alcohol testing
               | into "government" testing. See Skinner, 489 U.S. at 615.
               | [...] Federal law requires "electronic communication
               | service providers" like Google to notify NCMEC when they
               | become aware of child pornography. 18 U.S.C. SS 2258A(a).
               | But this mandate compels providers only to report child
               | pornography that they know of; it does not compel them to
               | search for child pornography of which they are unaware.
        
               | voidnullnil wrote:
               | Am I missing something? Apple says they literally scan
               | stuff locally on your iCrap now and call the police on
               | you if you have $badstuff. Nobody should be having their
               | data scanned in the first place. Is iCloud unencryped?
               | Such a thing exists in 2021? I've been using end to end
               | crypto since 2000. I don't understand why consumers want
               | their devices to do all kinds of special non-utilitarian
               | stuff (I mean I totally understand, it's called
               | politics).
               | 
               | This new iCrap is like a toaster that reports you if you
               | put illegally imported bread in it. It will be just like
               | the toaster which will have no measureable impact on
               | illegal imports. Even if $badguys are so dumb to continue
               | using the tech (iCloud???) and lots go to jail, lots more
               | will appear and simply avoid the exact specific cause
               | that sent previous batch to jail. They do not even thave
               | to think.
               | 
               | The problem with all this is that everyone is applauding
               | Apple for their bullshit, and so they will applaud the
               | government when they say "oh no, looks like criminals are
               | using non-backdoored data storage methods, what a
               | surprise! we need to make it illegal to have a data
               | storage service without going through a 6 month process
               | to setup a government approved remote auditing service".
               | 
               | Then there's also the fact that this is all a pile of
               | experimental crypto [1] being used to solve nothing.
               | Apple has created the exact situation of Cloudflare Pass:
               | they pointlessly made $badip solve a captcha to view a
               | read-only page, and provided a bunch of experimental
               | crypto in a browser plugin to let him use one captcha for
               | multiple domains (they would normally each require their
               | own captcha and corresponding session cookie). They later
               | stopped blocking $badip all together after they realized
               | they are wrong (this took literally 10 years).
               | 
               | 1. https://www.apple.com/child-safety/ "CSAM detection"
               | section
        
           | nullc wrote:
           | If there were no false positives there would be no legitimate
           | reason for Apple to review-- they would just be needlessly
           | exposing their employees to child abuse material.
           | 
           | But the fact that there is no legitimate reason according to
           | the system's design doesn't prevent there from being an
           | illegitimate reason: Apple's "review" undermines your legal
           | due process protection against warrantless search.
           | 
           | See US v. Ackerman (2016): The appeals court ruled that when
           | AOL forwarded an email with an attachment whos hash matched
           | the NCMEC database to law enforcement without anyone looking
           | at it, and law enforcement looked at the email without
           | obtaining a warrant was an unlawful search and had AOL looked
           | at it first (which they can do by virtue of your agreement
           | with them) and gone "yep, thats child porn" and reported it,
           | it wouldn't have been an unlawful search.
        
         | fortran77 wrote:
         | So we have an Apple employee, the type of person who gets
         | extremely offended over such things as "Chaos Monkeys,"
         | deciding if someone is a criminal? No thanks!
        
       | bastawhiz wrote:
       | Correct me if I'm wrong, but nowhere in Apple's announcement do
       | they mention "perceptual" hashing. I've searched through some of
       | the PDFs they link as well, but those also don't seem to mention
       | the word "perceptual". Can someone point out exactly where this
       | is mentioned?
        
         | rcarback wrote:
         | "NeuralHash is a perceptual hashing function"
         | 
         | https://www.apple.com/child-safety/pdf/CSAM_Detection_Techni...
        
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