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Google’s TOS doesn’t eliminate a user’s Fourth Amendment rights, judge rules [pdf]

403 points by coloneltcb 2y ago

henryfjordan 2y ago
The judge doesn't really understand a hash well. They say things like "Google assigned a hash" which is not true, Google calculated the hash. Also I'm surprised the 3rd-party doctrine doesn't apply. There's the "private search doctrine" mentioned but generally you don't have an expectation of privacy for things you share with Google
- curiousllama 2y ago
  Out of curiosity, what is false positive rate of a hash match? If the FPR is comparable to asking a human "are these the same image?", then it would seem to be equivalent to a visual search. I wonder if (or why) human verification is actually necessary here.
  - nokcha 2y ago
    For non-broken cryptographic hashes (e.g., SHA-256), the false-positive rate is negligible. Indeed, cryptographic hashes were designed so that even nation-state adversaries do not have the resources to generate two inputs that hash to the same value. See also: https://en.wikipedia.org/wiki/Collision_resistance https://en.wikipedia.org/wiki/Collision_resistance https://en.wikipedia.org/wiki/Preimage_attack https://en.wikipedia.org/wiki/Preimage_attack
    - int_19h 2y ago
      These are not the kinds of hashes used for CSAM detection, though, because that would only work for the exact pixel-by-pixel copy - any resizing, compression etc would drastically change the hash. Instead, systems like these use perceptual hashing, in which similar inputs produce similar hashes, so that one can test for likeness. Those have much higher collision rates, and are also much easier to deliberately generate collisions for.
  - gorjusborg 2y ago
    > Out of curiosity, what is false positive rate of a hash match? No way to know without knowledge of the 'proprietary hashing technology'. Theoretically though, a hash can have infinitely many inputs that produce the same output. Mismatching hash values from the same hashing algorithm can prove mismatching inputs, but matching hash values don't ensure matching inputs. > I wonder if (or why) human verification is actually necessary here It's not about frequency, it's about criticality of getting it right. If you are going to make a negatively life-altering report on someone, you'd better make sure the accusation is legitimate.
    - cool_dude85 2y ago
      I'd say the focus on hashing is a bit of a red herring. Most anyone would agree that the hash matching should probably form probable cause for a warrant, allowing a judge to sign off on the police searching (i.e., viewing) the image. So, if it's a collision, the cops get a warrant and open up your linux ISO or cat meme, and it's all good. Probably the ideal case is that they get a warrant to search the specific image, and are only able to obtain a warrant to search your home and effects, etc. if the image does appear to be CSAM. At issue here is the fact that no such warrant was obtained.
      - thrwaway1985882 2y ago
        I think it'll prove far more likely that the government creates incentives to lead Google/other providers to fully do the search on their behalf. The entire appeal seems to hinge on the fact that Google didn't actually view the image before passing it to NCMEC. Had Google policy been that all perceptual hash hits were reviewed by employees first, this would've likely been a one page denial.
      - ndriscoll 2y ago
        If the hash algorithm were CRC8, then obviously it should not be probable cause for anything. If it were SHA-3, then it's basically proof beyond reasonable doubt of what the file is. It seems reasonable to question how collisions behave.
  - ARandumGuy 2y ago
    Naively, 1/(2^{hash_size_in_bits}). Which is about 1 in 4 billion odds for a 32 bit hash, and gets astronomically low at higher bit counts. Of course, that's assuming a perfect, evenly distributed hash algorithm. And that's just the odds that any given pair of images has the same hash, not the odds that a hash conflict exists somewhere on the internet.
    - henryfjordan 2y ago
      You need to know the input space as well as the output space (hash size). If you have a 32bit hash but your input is only 16bit, you'll never have a collision (and you'll be wasting a ton of space on your hashes!). Image files can get into the megabytes though, so unless the output hash is large the potential for collisions is probably not all that low.
      - Dylan16807 2y ago
        You do not need to know the input space. Normal hash functions have pseudo-random outputs and they can collide even when the input space is much smaller than the output space. In fact, I'll go run ten million values, encoded into 24 bits each, through a 40 bit hash and count the collisions. My hash of choice will be a truncated sha256. ... I got 49 collisions.
  - deleted 2y ago
    [deleted]
  - cool_dude85 2y ago
    The reason human verification is necessary is that the government is relying on something called the "private search" doctrine to conduct the search without a warrant. This doctrine allows them to repeat a search already conducted by a private party (i.e., Google) without getting a warrant. Since Google didn't actually look at the file, the government is not able to look at the file without a warrant, as that search exceeds the scope of the initial search Google performed.
  - EVa5I7bHFq9mnYK 2y ago
    I doubt sha1 hashes are used for this. Those image hashes should match files regardless of orientation, cropping, resizing, re-compression, color correction etc. The collision could be far more frequent with these hashes.
    - bluGill 2y ago
      The hash should ideally match even if you use photoshop to cut the one person out of the picture and put that person into a different photo. I'm not sure if that is possible, but that is what we want.
- chaps 2y ago
  Erm, "Assigned" in this context is not new: https://law.justia.com/cases/federal/appellate-courts/ca5/17-41116/17-41116-2018-08-17.html https://law.justia.com/cases/federal/appellate-courts/ca5/17... "More simply, a hash value is a string of characters obtained by processing the contents of a given computer file and assigning a sequence of numbers and letters that correspond to the file’s contents." From 2018 in United States v. Reddick.
  - kwanbix 2y ago
    The calculation is what assigns the value.
    - toyg 2y ago
      Yes, Google's calculation.
      - oefnak 2y ago
        Did Google invent this hash?
        chaps 2y ago
        Why is that relevant? Google used a hashing function to persist a new record within a database. They created a record for this. Like I said in a sib. comment, this FOIA lawsuit goes into questions of hashing pretty well: https://caselaw.findlaw.com/court/us-2nd-circuit/2185910.html https://caselaw.findlaw.com/court/us-2nd-circuit/2185910.htm...
        deleted 2y ago
        [deleted]
    - deleted 2y ago
      [deleted]
    - chaps 2y ago
      No. The calculation is what determines what the assignation should be. It does not actually assign anything. This FOIA litigation by ACLU v ICE goes into this topic quite a lot: https://caselaw.findlaw.com/court/us-2nd-circuit/2185910.html https://caselaw.findlaw.com/court/us-2nd-circuit/2185910.htm...
- uniformlyrandom 2y ago
  Hash can be arbitrary, the only requirement is it is a deterministic one-way function.
  - Onavo 2y ago
    And it should be mostly bijective under most conditions. (This is obviously impossible in practice but hashes with common collisions shouldn't be allowed as legal evidence). Also neural/visual hashes like those used by big tech makes things tricky.
    - bluGill 2y ago
      The hash in question has many collisions. It it probably enough to get a warrant put it on a warrant, but it may not be enough to get a warrant without some other evidence. (it can be enough evidence to look for other public signs of evidence, or perhaps because there are a number of images that match different hashes)
- duxup 2y ago
  Google at some point decided how to calculate that hash and that influences what the value is right? Assigned seems appropriate in that context? Either way I think the judge's wording makes sense.
  - henryfjordan 2y ago
    Google assigned the hashing algorithm (maybe, assuming it wasn't chosen in some law somewhere, I know this CSAM hashing is something the big tech work on together). Once the hashing algorithm was assigned, individual values are computed or calculated. I don't think the judge's wording is all that bad but the word "assigned" is making it sound like Google exercised some agency when really all it did was apply a pre-chosen algorithm.
- axus 2y ago
  There's a password on my Google account, I totally expect to have privacy for anything I didn't choose to share with other people. The hash is kind of metadata recorded by Google, I feel like Google using it to keep child porn off their systems should be reasonable. Same ballpark as limiting my storage to 1GB based on file sizes. Sharing metadata without a warrant is a different question though.
  - cool_dude85 2y ago
    As should be expected from the lawyer world, it seems like whether you have an expectation of privacy using gmail comes down to very technical word choices in the ToS, which of course neither this guy nor anyone else has ever read. Specifically, it may be legally relevant to your expectation of privacy whether Google says they "may" or "will" scan for this stuff.
    - deleted 2y ago
      [deleted]
- mcosta 2y ago
  Does a lab assigns a DNA to you or does it calculate? Does two different labs DNA analysis are exactly equal?
  - TZubiri 2y ago
    Remember that you can use multiple different algorithms to calculate a hash.
superkuh 2y ago
It's crazy that the most dangerous people one regularly encounters can do anything they want as long as they believe they can do it. The good faith exemption has to be one of the most fascist laws on the books today. > "the good faith exception to the exclusionary rule supports denial of Maher’s suppression motion because, at the time authorities opened his uploaded file, they had a good faith basis to believe that no warrant was required." In no other context or career can you do anything you want and get away with it just as long as you say you thought you could. You'd think police offiers would be held to a higher standard, not no standard.
- deleted 2y ago
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- rmbyrro 2y ago
  I think the judge chose to relax a lot on this one due to the circumstances. Releasing a man in society found with 4,000 child porn photos in his computer would be a shame. But yeah, this opens too wide gates of precedence for tyranny, unfortunately...
- LudwigNagasena 2y ago
  > you do anything you want and get away with it just as long as you say you thought you could. Isn't that the motto of VC? Uber, AirBnB, WeWork, etc...
  - superkuh 2y ago
    Sorry, I should have been more explicit. I thought the context provided it. > you do any illegal action you want and get away with it just as long as you say you thought you could. And as for corporations: that's the point of incorporating. Reducing liability.
    - CRConrad 2y ago
      I don't think your clarification made much of a difference: A lot of the shit those VC-backed gig-worker-abusers do probably is (and certainly should be) illegal, too.
MathMonkeyMan 2y ago
The Fourth Amendment didn't help here, unfortunately. Or, perhaps fortunately. Still, 25 years for possessing kiddie porn, damn.
- bogwog 2y ago
  [flagged]
- rmbyrro 2y ago
  The harshness of sentence is not for the action of keeping the photos in itself, but the individual suffering and social damage caused by the actions that he incentivizes when he consumes such content.
  - shadowgovt 2y ago
    It's a reasonable argument, but a concerning one because it hinges on a couple of layers of indirection between the person engaging in consuming the content and the person doing the harm / person who is harmed. That's not outside the purview of US law (especially in the world post-reinterpretation of the Commerce Clause), but it is perhaps worth observing how close to the cliff of "For the good of Society, you must behave optimally, Citizen" such reasoning treads. For example: AI-generated CP (or hand-drawn illustrations) are viscerally repugnant, but does the same "individual suffering and social damage" reasoning apply to making them illegal? The FBI says yes to both in spite of the fact that we can name no human that was harmed or was unable to give consent in their fabrication (handwaving the source material for the AI, which if one chooses not to handwave it: drop that question on the floor and focus on under what reasoning we make hand-illustrated cartoons illegal to possess that couldn't be applied to pornography in general).
    - NoMoreNicksLeft 2y ago
      > The FBI says yes to both in spite of the fact that we can name no They have two arguments for this (that I am aware of). The first argument is a practical one, that AI-generated images would be indistinguishable from the "real thing", but that the real thing still being out there would complicate their efforts to investigate and prosecute. While everyone might agree that this is pragmatic, it's not necessarily constitutionally valid. We shouldn't prohibit activities based on whether these activities make it more difficult for authorities to investigate crimes. Besides, this one's technically moot... those producing the images could do so in such a way (from a technical standpoint) that they were instantly, automatically, and indisputably provable as being AI-generated. All images could be mandated to require embedded metadata which describes the model, seed, and so forth necessary to regenerate it. Anyone who needs to do so could push a button, the computer would attempt to regenerate the image from that seed, and the computer could even indicate that the two images matched (the person wouldn't even need to personally view the image for that to be the case). If the application indicated they did not match, then authorities could investigate it more thoroughly. The second argument is an economic one. That is, if a person "consumes" such material, they increase economic demand for it to be created. Even in a post-AI world, some "creation" would be criminal. Thus, the consumer of such imagery does cause (indirectly) more child abuse, and the government is justified in prohibiting AI-generated material. This is a weak argument on the best of days... one of the things that law enforcement efforts excel at is just this. When there are two varieties of a behavior, one objectionable and the other not, but both similar enough that they might at a glance be mistaken for one another, is that it can greatly disincentivize one without infringing the other. Being an economic argument, one of the things that might be said is that economic actors seek to reduce their risk of doing business, and so would gravitate to creating the legal variety of material. While their arguments are dumb, this filth's as reprehensible as anything. The only question worth asking or answering is, were (AI-generated) it legal, would it result in fewer children being harmed or not? It's commonly claimed that the easy availability of mainstream pornography has reduced the rate of rape since the mid-20th century.
vlovich123 2y ago
> As the district court correctly ruled in the alternative, the good faith exception to the exclusionary rule supports denial of Maher’s suppression motion because, at the time authorities opened his uploaded file, they had a good faith basis to believe that no warrant was required So this means this conviction is upheld but future convictions may be overturned if they similarly don't acquire a warrant?
- nickburns 2y ago
  This specific conviction upheld, yes. But no, this ruling doesn't speak to whether or not any future convictions may be overturned. It simply means that at the trial court level, future prosecutions will not be able to rely on the good faith exception to the exclusionary rule if warrantless inculpatory evidence is obtained under similar circumstances. If the governement were to try to present such evidence at trial and the trial judge were to admit it over the objection of the defendant, then that would present a specific ground for appeal. This ruling merely bolsters the 'better to get a warrant' spirit of the Fourth Amendment.
- SixtyHurtz 2y ago
  Yep, that's basically it.
- nordsieck 2y ago
  > the good faith exception to the exclusionary rule supports denial of Maher’s suppression motion because, at the time authorities opened his uploaded file, they had a good faith basis to believe that no warrant was required This "good faith exception" is so absurd I struggle to believe that it's real. Ordinary citizens are expected to understand and scrupulously abide by all of the law, but it's enough for law enforcement to believe that what they're doing is legal even if it isn't? What that is is a punch line from a Chapelle bit[1], not a reasonable part of the justice system. --- 1. https://www.youtube.com/watch?v=0WlmScgbdws https://www.youtube.com/watch?v=0WlmScgbdws
  - bluGill 2y ago
    The courts accept good faith arguments at times. They will give reduced sentences or even none at all if they think you acted in good faith. There are enough situations where it is legal to kill someone that there are laws to make it clear that is a legal situation where one person can kill another (hopefully they never apply to you). Note that this case is not about ignorance of the law. This is I knew the law and was trying to follow it - I just honestly thought it didn't apply because of some tricky situation that isn't 100% clear.
uniformlyrandom 2y ago
> Google’s hash match may well have established probable cause for a warrant to allow police to conduct a visual examination of the Maher file. Very reasonable. Google can flag accounts as CP, but then a judge still needs to issue a warrant for the police to actually go and look at the file. Good job court. Extra points for reasoning about hash values.
- kulahan 2y ago
  I'm trying to imagine a more "real-world" example of this to see how I feel about it. I dislike that there is yet another loophole to gain access to peoples' data for legal reasons, but this does feel like a reasonable approach and a valid goal to pursue. I guess it's like if someone noticed you had a case shaped exactly like a machine gun, told the police, and they went to check if it was registered or not? I suppose that seems perfectly reasonable, but I'm happy to hear counter-arguments.
  - cool_dude85 2y ago
    I think the real-world analogy would be to say that the case is shaped exactly like a machine gun and the hotel calls the police, who then open the case without a warrant. The "private search" doctrine allows the police to repeat a search done by a private party, but here (as in the machine gun case), the case was not actually searched by a private party.
  - aiforecastthway 2y ago
    The main factual components are as follows: Party A has rented out property to Party B. Party A performs surveillance on or around the property with Party B's knowledge and consent. Party A discovers very high probability evidence that Party B is committing crimes within the property, and then informs the police of their findings. Police obtain a warrant, using Party A's statements as evidence. The closest "real world" analogy that comes to mind might be a real estate management company uses security cameras or some other method to determine that there is a crime occurring in a space that they are renting out to another party. The real estate management company then sends evidence to the police. In the case of real property -- rental housing and warehouse/storage space in particular -- this happens all the time. I think that this ruling is imminently reasonable as a piece of case law (ie, the judge got the law as it exists correct). I also thing this precedent would strike a healthy policy balance as well (ie, the law as it exists if interpreted how the judge in this case interprets it would a good policy situation).
shadowgovt 2y ago
Wow, do I ever not know how I feel about the "good faith exception." It feels like it incentivizes the police to minimize their understanding of the law so that they can believe they are following it.
- tristor 2y ago
  > It feels like it incentivizes the police to minimize their understanding of the law so that they can believe they are following it. That's a bingo. That's exactly what they do, and why so many cops know less about the law than random citizens. A better society would have high standards for the knowledge expected of police officers, including things like requiring 4-year criminal justice or pre-law degree to be eligible to be hired, rather than capping IQ and preferring people who have had prior experience in conducting violent actions.
  - ninalanyon 2y ago
    In some countries you are required to study the law in order to become a police officer. It's part of the curriculum in the three year bachelor level course you must pass to become a police officer in Norway for instance. See https://en.wikipedia.org/wiki/Norwegian_Police_University_College https://en.wikipedia.org/wiki/Norwegian_Police_University_Co... and https://en.wikipedia.org/wiki/Norwegian_Police_Service https://en.wikipedia.org/wiki/Norwegian_Police_Service
    - tristor 2y ago
      Yes, this likely explains part of why the Norwegian police behave like professionals who are trying to do their job with high standards of performance and behavior and the police in the US behave like a bunch of drinking buddies that used to be bullies in high school trying to find their next target to harass.
- pavon 2y ago
  The good faith exception requires the belief be reasonable. Ignorance of clearly settled law is not reasonable, it should be a situation where the law was unclear, had conflicting interpretations or could otherwise be interpreted the way the police did by a reasonable person.
naet 2y ago
It seems like a large part of the ruling hinges on the fact that Google matched the image hash to a hash of a known child pornography image, but didn't require an employee to actually look at that image before reporting it to the police. If they had visually confirmed it was the image they suspected it was based on the hash then no warrant would have been required, but the judge reads that the image hash match is not equivalent to a visual confirmation of the image. Maybe there's some slight doubt in whether or not the image could be a hash collision, which depends on the hash method. It may be incredibly unlikely (near impossible?) for any hash collision depending on the specific hash strategy. I think it would obviously be less than ideal for Google to require an employee visually inspect child pornography identified by image hash before informing a legal authority like the police. So it seems more likely that the remedy to this situation would be for the police to obtain a warrant after getting the tip but before requesting the raw data from Google. Would the image hash match qualify as probable cause enough for a warrant? On page 4 the judge stops short of setting precedence on whether it would have or not. Seems likely that it would be a solid probable cause to me, but sometimes judges or courts have a unique interpretation of technology that I don't always share, and leaving it open to individual interpretation can lead to conflicting results.
- crooked-v 2y ago
  The hashes involved in stuff like this, as with copyright auto-matching, are perceptual hashes (https://en.wikipedia.org/wiki/Perceptual_hashing https://en.wikipedia.org/wiki/Perceptual_hashing), not cryptographic hashes. False matches are common enough that perceptual hashing attacks are already a thing in use to manipulate search engine results (see the example in random paper on the subject https://gangw.cs.illinois.edu/PHashing.pdf https://gangw.cs.illinois.edu/PHashing.pdf).
  - bluGill 2y ago
    It seems like that is very relevant information that was not considered by the court. If this was a cryptographic hash I would say with high confidence that this is the same image and so Google examined it - there is a small chance that some unrelated file (which might not even be a picture) matches but odds are the universe will end before that happens and so the courts can consider it the same image for search purposes. However because there are many false positive cases there is reasonable odds that the image is legal and so a higher standard for search is needed - a warrant.
qubitly 2y ago
So now an algorithm can interpret the law better than a judge. It’s amazing how technology becomes judge and jury while privacy rights are left to a good faith interpretation. Are we really okay with letting an algorithmic click define the boundaries of privacy?
- anigbrowl 2y ago
  The algorithm is interpreting whether one image file matches another, a purely probabilistic issue.
TZubiri 2y ago
"That, however, does not mean that Maher is entitled to relief from conviction. As the district court correctly ruled in the alternative, the good faith exception to the exclusionary rule supports denial of Maher’s suppression motion because, at the time authorities opened his uploaded file, they had a good faith basis to believe that no warrant was required." "Defendant [..] stands convicted following a guilty plea in the United States District Court for the Northern District of New York (Glenn T. Suddaby, Judge) of both receiving and possessing approximately 4,000 images and five videos depicting child pornography" A win for google, for the us judicial system, and for constitutional rights. A loss for child abusers.
- rangestransform 2y ago
  Constitutional rights did not win enough, it should be that violating constitutional rights means the accused goes free, period, end of story
  - TZubiri 2y ago
    You forgot your IANAL, but thankfully it's obvious. That's a ridiculous desire. In that world, if I delete your comment, and you kill me in retaliation, you should be let free if you argue that my deleting your comment infringed your right to free speech?
    - rangestransform 2y ago
      What I mean specifically is that because the police saw illegally obtained evidence, all evidence collected afterward after that point should be considered fruit of the poisoned tree and inadmissible
      - ndileas 2y ago
        I think reasonable people can disagree on this. Fruit of the poisoned tree doctrines eliminate bad incentives for law enforcement to commit crimes in their investigations. But when doctrines such as this cause the guilty to go free, it erodes public confidence in the rule of law. Like many things, its a tradeoff - and the legal system is a process of discovery and adaptation, not some simplistic set of unchangeable rules. Justice for one must always be upheld. I think this ruling is pretty good at threading the line here.
ninalanyon 2y ago
> the private search doctrine, which authorizes a government actor to repeat a search already conducted by a private party without securing a warrant. IANAL, etc. Does that mean that if someone breaks in to your house in search of drugs, finds and steals some, and is caught by the police and confesses all that the police can then search your house without a warrant?
- zeroonetwothree 2y ago
  I think the private search would have to be legal.
- thrwaway1985882 2y ago
  IANAL either, but from what I've read before the courts treat searches of your home with extra care under the 4th Amendment. At least one circuit has pushed back on applying private search cases to residences, and that was for a hotel room[0]: > Unlike the package in Jacobsen, however, which "contained nothing but contraband," Allen's motel room was a temporary abode containing personal possessions. Allen had a legitimate and significant privacy interest in the contents of his motel room, and this privacy interest was not breached in its entirety merely because the motel manager viewed some of those contents. Jacobsen, which measured the scope of a private search of a mail package, the entire contents of which were obvious, is distinguishable on its facts; this Court is unwilling to extend the holding in Jacobsen to cases involving private searches of residences. So under your hypothetical, I'd expect the police would be able to test "your drugs" that they confiscated from the thief, and use any findings to apply for a warrant for a search of your house, but any search without a warrant would be illegal. [0] https://casetext.com/case/us-v-allen-167 https://casetext.com/case/us-v-allen-167
IronWolve 2y ago
Was using those md5 sums on images for flagging images 20 years ago for the government, occasional false positives, but the safety team would review those, not operations. My only role was to burn the users account to a dvd (via a script) and have the police officer pick up the dvd, we never touched the disk, and only burned the disk with a warrant. (we never saw/touched the users data...) Figured this common industry standard for chain of custody for evidence. Same with police videos, they are uploaded to the courts digital evidence repository, and everyone who looks at the evidence is logged. Seems like a standard legal process was followed.
p0w3n3d 2y ago
The problem with the internet nowadays is that a few big players are making up their own law. Very often it is against local laws, but nobody can fight with it. For example someone created some content but other person uploaded it and got better scores which rendered the original poster blocked. Another example: children were playing a violin concert and the audio got removed due to alleged copyright violation. No possibility to appeal, nobody sane would go to court. It just goes this way...
zeroonetwothree 2y ago
The 9th circuit ruled the same way a few years ago: https://www.insideprivacy.com/data-privacy/ninth-circuits-interpretation-of-private-search-exception-to-the-fourth-amendment-contributes-to-growing-tension-among-circuit-courts/ https://www.insideprivacy.com/data-privacy/ninth-circuits-in...
nwhnwh 2y ago
What is the context of this?
austin-cheney 2y ago
Status quo, there is no change here. The old example is the email server administrator. If the email administrator has to view the contents of user messages as a part of regular maintenance and that email administrator notices lawful violations in those user messages they can report it to law enforcement. In that case law enforcement can receive the material without a warrant only if law enforcement never asked for it before it was gifted to them. There are no fourth amendment protections provided to offenders in this scenario of third party accidental discovery. Typically, in these cases the email administrator does not have an affirmed requirement to report lawful violations to law enforcement unless specific laws claim otherwise. If on the other hand law enforcement approaches that email administrator to fish for illegal user content then that email administrator has become an extension of law enforcement and any evidence discovered cannot be used in a criminal proceeding. Likewise, if the email administrator was intentionally looking through email messages for violations of law even not at the request of law enforcement they are still acting as agents of the law. In that case discovery was intentional and not an unintentional product of system maintenance. There is a third scenario: obscenity. Obscenity is illegal intellectual property, whether digital or physical, as defined by criminal code. Possession of obscene materials is a violation of criminal law for all persons, businesses, and systems in possession. In that case an email administrator that accidentally discovers obscene material does have a required obligation to report their discoveries, typically through their employer's corporate legal process, to law enforcement. Failures to disclose such discoveries potentially aligns the system provider to the illegal conduct of the violating user. Google's discovery, though, was not accidental as a result of system maintenance. It was due to an intentional discovery mechanism based on stored hashes, which puts Google's conduct in line with law enforcement even if they specified their conduct in their terms of service. That is why the appeals court claims the district court erred by denying the defendant's right to suppression on fourth amendment grounds. The saving grace for the district court was a good faith exception, such as inevitable discovery. The authenticity and integrity of the hash algorithm was never in question by any party so no search for violating material was necessary, which established probably cause thus allowing law enforcement reasonable grounds to proceed to trial. No warrant was required because the evidence was likely sufficient at trial even if law enforcement did not directly view image in question, but they did verify the image. None of that was challenged by either party. What was challenged was just Google's conduct.
anigbrowl 2y ago
Well let's look at how this actually played out. - Defendant was in fact sending CP through his gmail. - gmail correctly detects and flags it based on hash value - Google sends message to NCMEC based on hash value - NCMEC sends it to police based on hash value Now police are facing the obvious question, is this actually CP? They open the image, determine it is, then get a warrant to search his gmail account, and (later) another warrant to search his home. The court here is saying they should have got a warrant to even look at the image in the first place. But warrants only issue on probable cause. What's the PC here? The hash value. What's the probability of hash collisions? Non-zero but very low. The practical upshot of this is that all reports from NCMEC will now go through an extra step of the police submitting a copy of the report with the hash value and some boilerplate document saying 'based on my law enforcement experience, hash values are pretty reliable indicators of fundamental similarity', and the warrant application will then be rubber stamped by a judge. An analogous situation would be where I send a sealed envelope with some documents to the police, writing on the outside 'I believe the contents of this envelope are proof that John Doe committed [specific crime]', and the police have to get a warrant to open the envelope. It's arguably more legally consistent, but in practice it just creates an extra stage of legal bureaucracy/delay with no appreciable impact on the eventual outcome. Recall that the standard for issuance of a warrant is 'probable cause', not 'mathematically proven cause'. Hash collisions are a possibility, but a sufficiently unlikely one that it doesn't matter. Probable cause means 'a fair probability' based on independent evidence of some kind - testimony, observation, forensic results or so. Even a shitty hash function that's only 90% reliable is going to meet that threshold. In the 10% of cases where the opened file turns out to be a random image with no pornographic content it's a 'no harm no foul' situation. For reference, a primer on hash collision probabilities: https://preshing.com/20110504/hash-collision-probabilities/ https://preshing.com/20110504/hash-collision-probabilities/ and a more detailed examination of common perceptual hashing algorithms (skip to table 3 for the collision probabilities): https://ceur-ws.org/Vol-2904/81.pdf https://ceur-ws.org/Vol-2904/81.pdf I think what a lot of people are implicitly arguing here is that the detection system needs to be perfect before anyone can do anything. Nobody wants the job of examining images to check if they're CP or not, so we've outsourced it to machines that do so with good-but-not-perfect accuracy and then pass the hot potato around until someone has to pollute their visual cortex with it. Obviously we don't want to arrest or convict people based on computer output alone, but how good does it have to be (in % or odds terms) in order to begin an investigation - not of the alleged criminal, but of the evidence itself? Should companies like Google have to submit an estimate of the probability of hash collisions using their algorithm and based on the number of image hashes that exist on their servers at any given moment? Should they be required to submit source code used to derive that? What about the microcode of the silicon substrate on which the calculation is performed? All other things being equal, what improvement will result here from adding another layer of administrative processing, whose outcome is predetermined?
fngjdflmdflg 2y ago
>please use the original title, unless it is misleading or linkbait; don't editorialize. (@dang) On topic, I like this quote from the first page of the opinion: >A “hash” or “hash value” is “(usually) a short string of characters generated from a much larger string of data (say, an electronic image) using an algorithm—and calculated in a way that makes it highly unlikely another set of data will produce the same value.” United States v. Ackerman, 831 F.3d 1292, 1294 (10th Cir. 2016) (Gorsuch, J.). It's amusing to me that they use a supreme court case as a reference for what a hash is rather than eg. a textbook. It makes sense when you consider how the court system works but it is amusing nonetheless that the courts have their own body of CS literature. Maybe someone could publish a "CS for Judges" book that teaches as much CS as possible using only court decisions. That could actually have a real use case when you think of it. (As other commenters pointed out, the hashing definition given here could use a bit more qualification, and should at least differentiate between neural hashes and traditional ones like MD5, especially as it relates to the likeliness that "another set of data will produce the same value." Perhaps that could be an author's note in my "CS for Judges" book.)
- qnleigh 2y ago
  I bet that book would end up with some very strange content, like attributing the invention of all sorts of obvious things to patent trolls.
- Terr_ 2y ago
  > Maybe someone could publish a "CS for Judges" book At last, a form of civic participation which seems both helpful and exciting to me. That said, I am worried that lot of necessary content may not be easy to introduce with hard precedent, and direct advice or dicta might somehow (?) not be permitted in a case since it's not adversarial... A new career as a professional expert witness--even on computer topics--sounds rather dreary.
- Detrytus 2y ago
  What's so weird about this? CS literature is not legally binding in any way. Of course a judge would rather quote a previous ruling by fellow judge than a textbook, Wikipedia, or similar sources.
foota 2y ago
Is this because Google is compelled to report this to the authorities? I would have thought any company could voluntarily submit anything to the police.
briandear 2y ago
Serious question: a Google employee is not law enforcement. So if they are examining child pornography, in even only to identify it, aren’t they breaking the law? 18 U.S.C. § 2252 … c) Affirmative Defense.—It shall be an affirmative defense to a charge of violating paragraph (4) of subsection (a) that the defendant— (1) possessed less than three matters containing any visual depiction proscribed by that paragraph; and (2) promptly and in good faith, and without retaining or allowing any person, other than a law enforcement agency, to access any visual depiction or copy thereof— (A) took reasonable steps to destroy each such visual depiction; or (B) reported the matter to a law enforcement agency and afforded that agency access to each such visual depiction. So the Google employee would both have to “promptly” notify law enforcement AND not show it to any other person unless law enforcement and also have fewer than three pieces of content. And additionally, assigning hashes/etc — does that mean the file was preserved (otherwise what’s the hash representing? A photo they once found and then destroyed? How could law enforcement prove that the hash represented a prohibited image in order to establish probable cause?) “we say some random string of characters represents an image that we saw is child porn, so now you can issue a warrant.” What protections does the user have against a warrant being issued under false information? If the original image no longer exists, then how could the warrant be challenged? If the original image does exist — is Google storing it? And if they are storing it, aren’t they themselves breaking the law? In other words, do Google servers knowingly have child pornography on them? And does a private employee have immunity from prosecution if they don’t immediately notify law enforcement and also don’t show anyone else? I could see an instance where an employee shows his or her supervisor prior to calling law enforcement — which would be a violation of that law since the law explicitly says “any” person other than law enforcement. I am being somewhat tedious here, but I am genuinely interested in how Google can handle this without breaking the law themselves — more specifically the employee who, at the time of classifying the image, is in possession of illegal content. And does Google have some de facto exemption that wouldn’t apply to a smaller founder who had to contend with user created content and followed the same “assigning a hash” process as Google? What are the best (legal) practices around this, specifically around smaller companies that might have to contend with these issues?
- dsign 2y ago
  I guess it's always grey area for Google. But most likely, their contractors are overseas, and they contract their work to a third party in a third country. It's entirely possible that the business has gone full-circle and the same studios deliver CP and the CP hashes.
dsign 2y ago
So, Google is examining billion of files from their customers, and reporting said customers to the police automatically, on the basis of a hash match?
- mr90210 2y ago
  Are you familiar with the story of father who lost 10 years of photos of his child because Google flagged a few photos as child porn? Their servers their data, at least that’s what it seems like.

403 points by coloneltcb 2y ago

The judge doesn't really understand a hash well. They say things like "Google assigned a hash" which is not true, Google calculated the hash. Also I'm surprised the 3rd-party doctrine doesn't apply. There's the "private search doctrine" mentioned but generally you don't have an expectation of privacy for things you share with Google

curiousllama 2y ago
Out of curiosity, what is false positive rate of a hash match? If the FPR is comparable to asking a human "are these the same image?", then it would seem to be equivalent to a visual search. I wonder if (or why) human verification is actually necessary here.
- nokcha 2y ago
  For non-broken cryptographic hashes (e.g., SHA-256), the false-positive rate is negligible. Indeed, cryptographic hashes were designed so that even nation-state adversaries do not have the resources to generate two inputs that hash to the same value. See also: https://en.wikipedia.org/wiki/Collision_resistance https://en.wikipedia.org/wiki/Collision_resistance https://en.wikipedia.org/wiki/Preimage_attack https://en.wikipedia.org/wiki/Preimage_attack
  - int_19h 2y ago
    These are not the kinds of hashes used for CSAM detection, though, because that would only work for the exact pixel-by-pixel copy - any resizing, compression etc would drastically change the hash. Instead, systems like these use perceptual hashing, in which similar inputs produce similar hashes, so that one can test for likeness. Those have much higher collision rates, and are also much easier to deliberately generate collisions for.
- gorjusborg 2y ago
  > Out of curiosity, what is false positive rate of a hash match? No way to know without knowledge of the 'proprietary hashing technology'. Theoretically though, a hash can have infinitely many inputs that produce the same output. Mismatching hash values from the same hashing algorithm can prove mismatching inputs, but matching hash values don't ensure matching inputs. > I wonder if (or why) human verification is actually necessary here It's not about frequency, it's about criticality of getting it right. If you are going to make a negatively life-altering report on someone, you'd better make sure the accusation is legitimate.
  - cool_dude85 2y ago
    I'd say the focus on hashing is a bit of a red herring. Most anyone would agree that the hash matching should probably form probable cause for a warrant, allowing a judge to sign off on the police searching (i.e., viewing) the image. So, if it's a collision, the cops get a warrant and open up your linux ISO or cat meme, and it's all good. Probably the ideal case is that they get a warrant to search the specific image, and are only able to obtain a warrant to search your home and effects, etc. if the image does appear to be CSAM. At issue here is the fact that no such warrant was obtained.
    - thrwaway1985882 2y ago
      I think it'll prove far more likely that the government creates incentives to lead Google/other providers to fully do the search on their behalf. The entire appeal seems to hinge on the fact that Google didn't actually view the image before passing it to NCMEC. Had Google policy been that all perceptual hash hits were reviewed by employees first, this would've likely been a one page denial.
    - ndriscoll 2y ago
      If the hash algorithm were CRC8, then obviously it should not be probable cause for anything. If it were SHA-3, then it's basically proof beyond reasonable doubt of what the file is. It seems reasonable to question how collisions behave.
- ARandumGuy 2y ago
  Naively, 1/(2^{hash_size_in_bits}). Which is about 1 in 4 billion odds for a 32 bit hash, and gets astronomically low at higher bit counts. Of course, that's assuming a perfect, evenly distributed hash algorithm. And that's just the odds that any given pair of images has the same hash, not the odds that a hash conflict exists somewhere on the internet.
  - henryfjordan 2y ago
    You need to know the input space as well as the output space (hash size). If you have a 32bit hash but your input is only 16bit, you'll never have a collision (and you'll be wasting a ton of space on your hashes!). Image files can get into the megabytes though, so unless the output hash is large the potential for collisions is probably not all that low.
    - Dylan16807 2y ago
      You do not need to know the input space. Normal hash functions have pseudo-random outputs and they can collide even when the input space is much smaller than the output space. In fact, I'll go run ten million values, encoded into 24 bits each, through a 40 bit hash and count the collisions. My hash of choice will be a truncated sha256. ... I got 49 collisions.
- deleted 2y ago
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- cool_dude85 2y ago
  The reason human verification is necessary is that the government is relying on something called the "private search" doctrine to conduct the search without a warrant. This doctrine allows them to repeat a search already conducted by a private party (i.e., Google) without getting a warrant. Since Google didn't actually look at the file, the government is not able to look at the file without a warrant, as that search exceeds the scope of the initial search Google performed.
- EVa5I7bHFq9mnYK 2y ago
  I doubt sha1 hashes are used for this. Those image hashes should match files regardless of orientation, cropping, resizing, re-compression, color correction etc. The collision could be far more frequent with these hashes.
  - bluGill 2y ago
    The hash should ideally match even if you use photoshop to cut the one person out of the picture and put that person into a different photo. I'm not sure if that is possible, but that is what we want.
chaps 2y ago
Erm, "Assigned" in this context is not new: https://law.justia.com/cases/federal/appellate-courts/ca5/17-41116/17-41116-2018-08-17.html https://law.justia.com/cases/federal/appellate-courts/ca5/17... "More simply, a hash value is a string of characters obtained by processing the contents of a given computer file and assigning a sequence of numbers and letters that correspond to the file’s contents." From 2018 in United States v. Reddick.
- kwanbix 2y ago
  The calculation is what assigns the value.
  - toyg 2y ago
    Yes, Google's calculation.
    - oefnak 2y ago
      Did Google invent this hash?
      - chaps 2y ago
        Why is that relevant? Google used a hashing function to persist a new record within a database. They created a record for this. Like I said in a sib. comment, this FOIA lawsuit goes into questions of hashing pretty well: https://caselaw.findlaw.com/court/us-2nd-circuit/2185910.html https://caselaw.findlaw.com/court/us-2nd-circuit/2185910.htm...
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  - chaps 2y ago
    No. The calculation is what determines what the assignation should be. It does not actually assign anything. This FOIA litigation by ACLU v ICE goes into this topic quite a lot: https://caselaw.findlaw.com/court/us-2nd-circuit/2185910.html https://caselaw.findlaw.com/court/us-2nd-circuit/2185910.htm...
uniformlyrandom 2y ago
Hash can be arbitrary, the only requirement is it is a deterministic one-way function.
- Onavo 2y ago
  And it should be mostly bijective under most conditions. (This is obviously impossible in practice but hashes with common collisions shouldn't be allowed as legal evidence). Also neural/visual hashes like those used by big tech makes things tricky.
  - bluGill 2y ago
    The hash in question has many collisions. It it probably enough to get a warrant put it on a warrant, but it may not be enough to get a warrant without some other evidence. (it can be enough evidence to look for other public signs of evidence, or perhaps because there are a number of images that match different hashes)
duxup 2y ago
Google at some point decided how to calculate that hash and that influences what the value is right? Assigned seems appropriate in that context? Either way I think the judge's wording makes sense.
- henryfjordan 2y ago
  Google assigned the hashing algorithm (maybe, assuming it wasn't chosen in some law somewhere, I know this CSAM hashing is something the big tech work on together). Once the hashing algorithm was assigned, individual values are computed or calculated. I don't think the judge's wording is all that bad but the word "assigned" is making it sound like Google exercised some agency when really all it did was apply a pre-chosen algorithm.
axus 2y ago
There's a password on my Google account, I totally expect to have privacy for anything I didn't choose to share with other people. The hash is kind of metadata recorded by Google, I feel like Google using it to keep child porn off their systems should be reasonable. Same ballpark as limiting my storage to 1GB based on file sizes. Sharing metadata without a warrant is a different question though.
- cool_dude85 2y ago
  As should be expected from the lawyer world, it seems like whether you have an expectation of privacy using gmail comes down to very technical word choices in the ToS, which of course neither this guy nor anyone else has ever read. Specifically, it may be legally relevant to your expectation of privacy whether Google says they "may" or "will" scan for this stuff.
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mcosta 2y ago
Does a lab assigns a DNA to you or does it calculate? Does two different labs DNA analysis are exactly equal?
- TZubiri 2y ago
  Remember that you can use multiple different algorithms to calculate a hash.

superkuh 2y ago

It's crazy that the most dangerous people one regularly encounters can do anything they want as long as they believe they can do it. The good faith exemption has to be one of the most fascist laws on the books today. > "the good faith exception to the exclusionary rule supports denial of Maher’s suppression motion because, at the time authorities opened his uploaded file, they had a good faith basis to believe that no warrant was required." In no other context or career can you do anything you want and get away with it just as long as you say you thought you could. You'd think police offiers would be held to a higher standard, not no standard.

deleted 2y ago
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rmbyrro 2y ago
I think the judge chose to relax a lot on this one due to the circumstances. Releasing a man in society found with 4,000 child porn photos in his computer would be a shame. But yeah, this opens too wide gates of precedence for tyranny, unfortunately...
LudwigNagasena 2y ago
> you do anything you want and get away with it just as long as you say you thought you could. Isn't that the motto of VC? Uber, AirBnB, WeWork, etc...
- superkuh 2y ago
  Sorry, I should have been more explicit. I thought the context provided it. > you do any illegal action you want and get away with it just as long as you say you thought you could. And as for corporations: that's the point of incorporating. Reducing liability.
  - CRConrad 2y ago
    I don't think your clarification made much of a difference: A lot of the shit those VC-backed gig-worker-abusers do probably is (and certainly should be) illegal, too.

MathMonkeyMan 2y ago

The Fourth Amendment didn't help here, unfortunately. Or, perhaps fortunately. Still, 25 years for possessing kiddie porn, damn.

bogwog 2y ago
[flagged]
rmbyrro 2y ago
The harshness of sentence is not for the action of keeping the photos in itself, but the individual suffering and social damage caused by the actions that he incentivizes when he consumes such content.
- shadowgovt 2y ago
  It's a reasonable argument, but a concerning one because it hinges on a couple of layers of indirection between the person engaging in consuming the content and the person doing the harm / person who is harmed. That's not outside the purview of US law (especially in the world post-reinterpretation of the Commerce Clause), but it is perhaps worth observing how close to the cliff of "For the good of Society, you must behave optimally, Citizen" such reasoning treads. For example: AI-generated CP (or hand-drawn illustrations) are viscerally repugnant, but does the same "individual suffering and social damage" reasoning apply to making them illegal? The FBI says yes to both in spite of the fact that we can name no human that was harmed or was unable to give consent in their fabrication (handwaving the source material for the AI, which if one chooses not to handwave it: drop that question on the floor and focus on under what reasoning we make hand-illustrated cartoons illegal to possess that couldn't be applied to pornography in general).
  - NoMoreNicksLeft 2y ago
    > The FBI says yes to both in spite of the fact that we can name no They have two arguments for this (that I am aware of). The first argument is a practical one, that AI-generated images would be indistinguishable from the "real thing", but that the real thing still being out there would complicate their efforts to investigate and prosecute. While everyone might agree that this is pragmatic, it's not necessarily constitutionally valid. We shouldn't prohibit activities based on whether these activities make it more difficult for authorities to investigate crimes. Besides, this one's technically moot... those producing the images could do so in such a way (from a technical standpoint) that they were instantly, automatically, and indisputably provable as being AI-generated. All images could be mandated to require embedded metadata which describes the model, seed, and so forth necessary to regenerate it. Anyone who needs to do so could push a button, the computer would attempt to regenerate the image from that seed, and the computer could even indicate that the two images matched (the person wouldn't even need to personally view the image for that to be the case). If the application indicated they did not match, then authorities could investigate it more thoroughly. The second argument is an economic one. That is, if a person "consumes" such material, they increase economic demand for it to be created. Even in a post-AI world, some "creation" would be criminal. Thus, the consumer of such imagery does cause (indirectly) more child abuse, and the government is justified in prohibiting AI-generated material. This is a weak argument on the best of days... one of the things that law enforcement efforts excel at is just this. When there are two varieties of a behavior, one objectionable and the other not, but both similar enough that they might at a glance be mistaken for one another, is that it can greatly disincentivize one without infringing the other. Being an economic argument, one of the things that might be said is that economic actors seek to reduce their risk of doing business, and so would gravitate to creating the legal variety of material. While their arguments are dumb, this filth's as reprehensible as anything. The only question worth asking or answering is, were (AI-generated) it legal, would it result in fewer children being harmed or not? It's commonly claimed that the easy availability of mainstream pornography has reduced the rate of rape since the mid-20th century.

vlovich123 2y ago

> As the district court correctly ruled in the alternative, the good faith exception to the exclusionary rule supports denial of Maher’s suppression motion because, at the time authorities opened his uploaded file, they had a good faith basis to believe that no warrant was required So this means this conviction is upheld but future convictions may be overturned if they similarly don't acquire a warrant?

nickburns 2y ago
This specific conviction upheld, yes. But no, this ruling doesn't speak to whether or not any future convictions may be overturned. It simply means that at the trial court level, future prosecutions will not be able to rely on the good faith exception to the exclusionary rule if warrantless inculpatory evidence is obtained under similar circumstances. If the governement were to try to present such evidence at trial and the trial judge were to admit it over the objection of the defendant, then that would present a specific ground for appeal. This ruling merely bolsters the 'better to get a warrant' spirit of the Fourth Amendment.
SixtyHurtz 2y ago
Yep, that's basically it.
nordsieck 2y ago
> the good faith exception to the exclusionary rule supports denial of Maher’s suppression motion because, at the time authorities opened his uploaded file, they had a good faith basis to believe that no warrant was required This "good faith exception" is so absurd I struggle to believe that it's real. Ordinary citizens are expected to understand and scrupulously abide by all of the law, but it's enough for law enforcement to believe that what they're doing is legal even if it isn't? What that is is a punch line from a Chapelle bit[1], not a reasonable part of the justice system. --- 1. https://www.youtube.com/watch?v=0WlmScgbdws https://www.youtube.com/watch?v=0WlmScgbdws
- bluGill 2y ago
  The courts accept good faith arguments at times. They will give reduced sentences or even none at all if they think you acted in good faith. There are enough situations where it is legal to kill someone that there are laws to make it clear that is a legal situation where one person can kill another (hopefully they never apply to you). Note that this case is not about ignorance of the law. This is I knew the law and was trying to follow it - I just honestly thought it didn't apply because of some tricky situation that isn't 100% clear.

uniformlyrandom 2y ago

> Google’s hash match may well have established probable cause for a warrant to allow police to conduct a visual examination of the Maher file. Very reasonable. Google can flag accounts as CP, but then a judge still needs to issue a warrant for the police to actually go and look at the file. Good job court. Extra points for reasoning about hash values.

kulahan 2y ago
I'm trying to imagine a more "real-world" example of this to see how I feel about it. I dislike that there is yet another loophole to gain access to peoples' data for legal reasons, but this does feel like a reasonable approach and a valid goal to pursue. I guess it's like if someone noticed you had a case shaped exactly like a machine gun, told the police, and they went to check if it was registered or not? I suppose that seems perfectly reasonable, but I'm happy to hear counter-arguments.
- cool_dude85 2y ago
  I think the real-world analogy would be to say that the case is shaped exactly like a machine gun and the hotel calls the police, who then open the case without a warrant. The "private search" doctrine allows the police to repeat a search done by a private party, but here (as in the machine gun case), the case was not actually searched by a private party.
- aiforecastthway 2y ago
  The main factual components are as follows: Party A has rented out property to Party B. Party A performs surveillance on or around the property with Party B's knowledge and consent. Party A discovers very high probability evidence that Party B is committing crimes within the property, and then informs the police of their findings. Police obtain a warrant, using Party A's statements as evidence. The closest "real world" analogy that comes to mind might be a real estate management company uses security cameras or some other method to determine that there is a crime occurring in a space that they are renting out to another party. The real estate management company then sends evidence to the police. In the case of real property -- rental housing and warehouse/storage space in particular -- this happens all the time. I think that this ruling is imminently reasonable as a piece of case law (ie, the judge got the law as it exists correct). I also thing this precedent would strike a healthy policy balance as well (ie, the law as it exists if interpreted how the judge in this case interprets it would a good policy situation).

shadowgovt 2y ago

Wow, do I ever not know how I feel about the "good faith exception." It feels like it incentivizes the police to minimize their understanding of the law so that they can believe they are following it.

tristor 2y ago
> It feels like it incentivizes the police to minimize their understanding of the law so that they can believe they are following it. That's a bingo. That's exactly what they do, and why so many cops know less about the law than random citizens. A better society would have high standards for the knowledge expected of police officers, including things like requiring 4-year criminal justice or pre-law degree to be eligible to be hired, rather than capping IQ and preferring people who have had prior experience in conducting violent actions.
- ninalanyon 2y ago
  In some countries you are required to study the law in order to become a police officer. It's part of the curriculum in the three year bachelor level course you must pass to become a police officer in Norway for instance. See https://en.wikipedia.org/wiki/Norwegian_Police_University_College https://en.wikipedia.org/wiki/Norwegian_Police_University_Co... and https://en.wikipedia.org/wiki/Norwegian_Police_Service https://en.wikipedia.org/wiki/Norwegian_Police_Service
  - tristor 2y ago
    Yes, this likely explains part of why the Norwegian police behave like professionals who are trying to do their job with high standards of performance and behavior and the police in the US behave like a bunch of drinking buddies that used to be bullies in high school trying to find their next target to harass.
pavon 2y ago
The good faith exception requires the belief be reasonable. Ignorance of clearly settled law is not reasonable, it should be a situation where the law was unclear, had conflicting interpretations or could otherwise be interpreted the way the police did by a reasonable person.

naet 2y ago

It seems like a large part of the ruling hinges on the fact that Google matched the image hash to a hash of a known child pornography image, but didn't require an employee to actually look at that image before reporting it to the police. If they had visually confirmed it was the image they suspected it was based on the hash then no warrant would have been required, but the judge reads that the image hash match is not equivalent to a visual confirmation of the image. Maybe there's some slight doubt in whether or not the image could be a hash collision, which depends on the hash method. It may be incredibly unlikely (near impossible?) for any hash collision depending on the specific hash strategy. I think it would obviously be less than ideal for Google to require an employee visually inspect child pornography identified by image hash before informing a legal authority like the police. So it seems more likely that the remedy to this situation would be for the police to obtain a warrant after getting the tip but before requesting the raw data from Google. Would the image hash match qualify as probable cause enough for a warrant? On page 4 the judge stops short of setting precedence on whether it would have or not. Seems likely that it would be a solid probable cause to me, but sometimes judges or courts have a unique interpretation of technology that I don't always share, and leaving it open to individual interpretation can lead to conflicting results.

crooked-v 2y ago
The hashes involved in stuff like this, as with copyright auto-matching, are perceptual hashes (https://en.wikipedia.org/wiki/Perceptual_hashing https://en.wikipedia.org/wiki/Perceptual_hashing), not cryptographic hashes. False matches are common enough that perceptual hashing attacks are already a thing in use to manipulate search engine results (see the example in random paper on the subject https://gangw.cs.illinois.edu/PHashing.pdf https://gangw.cs.illinois.edu/PHashing.pdf).
- bluGill 2y ago
  It seems like that is very relevant information that was not considered by the court. If this was a cryptographic hash I would say with high confidence that this is the same image and so Google examined it - there is a small chance that some unrelated file (which might not even be a picture) matches but odds are the universe will end before that happens and so the courts can consider it the same image for search purposes. However because there are many false positive cases there is reasonable odds that the image is legal and so a higher standard for search is needed - a warrant.

qubitly 2y ago

So now an algorithm can interpret the law better than a judge. It’s amazing how technology becomes judge and jury while privacy rights are left to a good faith interpretation. Are we really okay with letting an algorithmic click define the boundaries of privacy?

anigbrowl 2y ago
The algorithm is interpreting whether one image file matches another, a purely probabilistic issue.

TZubiri 2y ago

"That, however, does not mean that Maher is entitled to relief from conviction. As the district court correctly ruled in the alternative, the good faith exception to the exclusionary rule supports denial of Maher’s suppression motion because, at the time authorities opened his uploaded file, they had a good faith basis to believe that no warrant was required." "Defendant [..] stands convicted following a guilty plea in the United States District Court for the Northern District of New York (Glenn T. Suddaby, Judge) of both receiving and possessing approximately 4,000 images and five videos depicting child pornography" A win for google, for the us judicial system, and for constitutional rights. A loss for child abusers.

rangestransform 2y ago
Constitutional rights did not win enough, it should be that violating constitutional rights means the accused goes free, period, end of story
- TZubiri 2y ago
  You forgot your IANAL, but thankfully it's obvious. That's a ridiculous desire. In that world, if I delete your comment, and you kill me in retaliation, you should be let free if you argue that my deleting your comment infringed your right to free speech?
  - rangestransform 2y ago
    What I mean specifically is that because the police saw illegally obtained evidence, all evidence collected afterward after that point should be considered fruit of the poisoned tree and inadmissible
    - ndileas 2y ago
      I think reasonable people can disagree on this. Fruit of the poisoned tree doctrines eliminate bad incentives for law enforcement to commit crimes in their investigations. But when doctrines such as this cause the guilty to go free, it erodes public confidence in the rule of law. Like many things, its a tradeoff - and the legal system is a process of discovery and adaptation, not some simplistic set of unchangeable rules. Justice for one must always be upheld. I think this ruling is pretty good at threading the line here.

ninalanyon 2y ago

> the private search doctrine, which authorizes a government actor to repeat a search already conducted by a private party without securing a warrant. IANAL, etc. Does that mean that if someone breaks in to your house in search of drugs, finds and steals some, and is caught by the police and confesses all that the police can then search your house without a warrant?

zeroonetwothree 2y ago
I think the private search would have to be legal.
thrwaway1985882 2y ago
IANAL either, but from what I've read before the courts treat searches of your home with extra care under the 4th Amendment. At least one circuit has pushed back on applying private search cases to residences, and that was for a hotel room[0]: > Unlike the package in Jacobsen, however, which "contained nothing but contraband," Allen's motel room was a temporary abode containing personal possessions. Allen had a legitimate and significant privacy interest in the contents of his motel room, and this privacy interest was not breached in its entirety merely because the motel manager viewed some of those contents. Jacobsen, which measured the scope of a private search of a mail package, the entire contents of which were obvious, is distinguishable on its facts; this Court is unwilling to extend the holding in Jacobsen to cases involving private searches of residences. So under your hypothetical, I'd expect the police would be able to test "your drugs" that they confiscated from the thief, and use any findings to apply for a warrant for a search of your house, but any search without a warrant would be illegal. [0] https://casetext.com/case/us-v-allen-167 https://casetext.com/case/us-v-allen-167

IronWolve 2y ago

Was using those md5 sums on images for flagging images 20 years ago for the government, occasional false positives, but the safety team would review those, not operations. My only role was to burn the users account to a dvd (via a script) and have the police officer pick up the dvd, we never touched the disk, and only burned the disk with a warrant. (we never saw/touched the users data...) Figured this common industry standard for chain of custody for evidence. Same with police videos, they are uploaded to the courts digital evidence repository, and everyone who looks at the evidence is logged. Seems like a standard legal process was followed.

p0w3n3d 2y ago

The problem with the internet nowadays is that a few big players are making up their own law. Very often it is against local laws, but nobody can fight with it. For example someone created some content but other person uploaded it and got better scores which rendered the original poster blocked. Another example: children were playing a violin concert and the audio got removed due to alleged copyright violation. No possibility to appeal, nobody sane would go to court. It just goes this way...

zeroonetwothree 2y ago

The 9th circuit ruled the same way a few years ago: https://www.insideprivacy.com/data-privacy/ninth-circuits-interpretation-of-private-search-exception-to-the-fourth-amendment-contributes-to-growing-tension-among-circuit-courts/ https://www.insideprivacy.com/data-privacy/ninth-circuits-in...

nwhnwh 2y ago

What is the context of this?

austin-cheney 2y ago

Status quo, there is no change here. The old example is the email server administrator. If the email administrator has to view the contents of user messages as a part of regular maintenance and that email administrator notices lawful violations in those user messages they can report it to law enforcement. In that case law enforcement can receive the material without a warrant only if law enforcement never asked for it before it was gifted to them. There are no fourth amendment protections provided to offenders in this scenario of third party accidental discovery. Typically, in these cases the email administrator does not have an affirmed requirement to report lawful violations to law enforcement unless specific laws claim otherwise. If on the other hand law enforcement approaches that email administrator to fish for illegal user content then that email administrator has become an extension of law enforcement and any evidence discovered cannot be used in a criminal proceeding. Likewise, if the email administrator was intentionally looking through email messages for violations of law even not at the request of law enforcement they are still acting as agents of the law. In that case discovery was intentional and not an unintentional product of system maintenance. There is a third scenario: obscenity. Obscenity is illegal intellectual property, whether digital or physical, as defined by criminal code. Possession of obscene materials is a violation of criminal law for all persons, businesses, and systems in possession. In that case an email administrator that accidentally discovers obscene material does have a required obligation to report their discoveries, typically through their employer's corporate legal process, to law enforcement. Failures to disclose such discoveries potentially aligns the system provider to the illegal conduct of the violating user. Google's discovery, though, was not accidental as a result of system maintenance. It was due to an intentional discovery mechanism based on stored hashes, which puts Google's conduct in line with law enforcement even if they specified their conduct in their terms of service. That is why the appeals court claims the district court erred by denying the defendant's right to suppression on fourth amendment grounds. The saving grace for the district court was a good faith exception, such as inevitable discovery. The authenticity and integrity of the hash algorithm was never in question by any party so no search for violating material was necessary, which established probably cause thus allowing law enforcement reasonable grounds to proceed to trial. No warrant was required because the evidence was likely sufficient at trial even if law enforcement did not directly view image in question, but they did verify the image. None of that was challenged by either party. What was challenged was just Google's conduct.

anigbrowl 2y ago

Well let's look at how this actually played out. - Defendant was in fact sending CP through his gmail. - gmail correctly detects and flags it based on hash value - Google sends message to NCMEC based on hash value - NCMEC sends it to police based on hash value Now police are facing the obvious question, is this actually CP? They open the image, determine it is, then get a warrant to search his gmail account, and (later) another warrant to search his home. The court here is saying they should have got a warrant to even look at the image in the first place. But warrants only issue on probable cause. What's the PC here? The hash value. What's the probability of hash collisions? Non-zero but very low. The practical upshot of this is that all reports from NCMEC will now go through an extra step of the police submitting a copy of the report with the hash value and some boilerplate document saying 'based on my law enforcement experience, hash values are pretty reliable indicators of fundamental similarity', and the warrant application will then be rubber stamped by a judge. An analogous situation would be where I send a sealed envelope with some documents to the police, writing on the outside 'I believe the contents of this envelope are proof that John Doe committed [specific crime]', and the police have to get a warrant to open the envelope. It's arguably more legally consistent, but in practice it just creates an extra stage of legal bureaucracy/delay with no appreciable impact on the eventual outcome. Recall that the standard for issuance of a warrant is 'probable cause', not 'mathematically proven cause'. Hash collisions are a possibility, but a sufficiently unlikely one that it doesn't matter. Probable cause means 'a fair probability' based on independent evidence of some kind - testimony, observation, forensic results or so. Even a shitty hash function that's only 90% reliable is going to meet that threshold. In the 10% of cases where the opened file turns out to be a random image with no pornographic content it's a 'no harm no foul' situation. For reference, a primer on hash collision probabilities: https://preshing.com/20110504/hash-collision-probabilities/ https://preshing.com/20110504/hash-collision-probabilities/ and a more detailed examination of common perceptual hashing algorithms (skip to table 3 for the collision probabilities): https://ceur-ws.org/Vol-2904/81.pdf https://ceur-ws.org/Vol-2904/81.pdf I think what a lot of people are implicitly arguing here is that the detection system needs to be perfect before anyone can do anything. Nobody wants the job of examining images to check if they're CP or not, so we've outsourced it to machines that do so with good-but-not-perfect accuracy and then pass the hot potato around until someone has to pollute their visual cortex with it. Obviously we don't want to arrest or convict people based on computer output alone, but how good does it have to be (in % or odds terms) in order to begin an investigation - not of the alleged criminal, but of the evidence itself? Should companies like Google have to submit an estimate of the probability of hash collisions using their algorithm and based on the number of image hashes that exist on their servers at any given moment? Should they be required to submit source code used to derive that? What about the microcode of the silicon substrate on which the calculation is performed? All other things being equal, what improvement will result here from adding another layer of administrative processing, whose outcome is predetermined?

fngjdflmdflg 2y ago

>please use the original title, unless it is misleading or linkbait; don't editorialize. (@dang) On topic, I like this quote from the first page of the opinion: >A “hash” or “hash value” is “(usually) a short string of characters generated from a much larger string of data (say, an electronic image) using an algorithm—and calculated in a way that makes it highly unlikely another set of data will produce the same value.” United States v. Ackerman, 831 F.3d 1292, 1294 (10th Cir. 2016) (Gorsuch, J.). It's amusing to me that they use a supreme court case as a reference for what a hash is rather than eg. a textbook. It makes sense when you consider how the court system works but it is amusing nonetheless that the courts have their own body of CS literature. Maybe someone could publish a "CS for Judges" book that teaches as much CS as possible using only court decisions. That could actually have a real use case when you think of it. (As other commenters pointed out, the hashing definition given here could use a bit more qualification, and should at least differentiate between neural hashes and traditional ones like MD5, especially as it relates to the likeliness that "another set of data will produce the same value." Perhaps that could be an author's note in my "CS for Judges" book.)

qnleigh 2y ago
I bet that book would end up with some very strange content, like attributing the invention of all sorts of obvious things to patent trolls.
Terr_ 2y ago
> Maybe someone could publish a "CS for Judges" book At last, a form of civic participation which seems both helpful and exciting to me. That said, I am worried that lot of necessary content may not be easy to introduce with hard precedent, and direct advice or dicta might somehow (?) not be permitted in a case since it's not adversarial... A new career as a professional expert witness--even on computer topics--sounds rather dreary.
Detrytus 2y ago
What's so weird about this? CS literature is not legally binding in any way. Of course a judge would rather quote a previous ruling by fellow judge than a textbook, Wikipedia, or similar sources.

foota 2y ago

Is this because Google is compelled to report this to the authorities? I would have thought any company could voluntarily submit anything to the police.

briandear 2y ago

Serious question: a Google employee is not law enforcement. So if they are examining child pornography, in even only to identify it, aren’t they breaking the law? 18 U.S.C. § 2252 … c) Affirmative Defense.—It shall be an affirmative defense to a charge of violating paragraph (4) of subsection (a) that the defendant— (1) possessed less than three matters containing any visual depiction proscribed by that paragraph; and (2) promptly and in good faith, and without retaining or allowing any person, other than a law enforcement agency, to access any visual depiction or copy thereof— (A) took reasonable steps to destroy each such visual depiction; or (B) reported the matter to a law enforcement agency and afforded that agency access to each such visual depiction. So the Google employee would both have to “promptly” notify law enforcement AND not show it to any other person unless law enforcement and also have fewer than three pieces of content. And additionally, assigning hashes/etc — does that mean the file was preserved (otherwise what’s the hash representing? A photo they once found and then destroyed? How could law enforcement prove that the hash represented a prohibited image in order to establish probable cause?) “we say some random string of characters represents an image that we saw is child porn, so now you can issue a warrant.” What protections does the user have against a warrant being issued under false information? If the original image no longer exists, then how could the warrant be challenged? If the original image does exist — is Google storing it? And if they are storing it, aren’t they themselves breaking the law? In other words, do Google servers knowingly have child pornography on them? And does a private employee have immunity from prosecution if they don’t immediately notify law enforcement and also don’t show anyone else? I could see an instance where an employee shows his or her supervisor prior to calling law enforcement — which would be a violation of that law since the law explicitly says “any” person other than law enforcement. I am being somewhat tedious here, but I am genuinely interested in how Google can handle this without breaking the law themselves — more specifically the employee who, at the time of classifying the image, is in possession of illegal content. And does Google have some de facto exemption that wouldn’t apply to a smaller founder who had to contend with user created content and followed the same “assigning a hash” process as Google? What are the best (legal) practices around this, specifically around smaller companies that might have to contend with these issues?

dsign 2y ago
I guess it's always grey area for Google. But most likely, their contractors are overseas, and they contract their work to a third party in a third country. It's entirely possible that the business has gone full-circle and the same studios deliver CP and the CP hashes.

dsign 2y ago

So, Google is examining billion of files from their customers, and reporting said customers to the police automatically, on the basis of a hash match?

mr90210 2y ago
Are you familiar with the story of father who lost 10 years of photos of his child because Google flagged a few photos as child porn? Their servers their data, at least that’s what it seems like.