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Why are anime catgirls blocking my access to the Linux kernel? (lock.cmpxchg8b.com)
submitted 1 year ago by to c/selfhosted@lemmy.world
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Some thoughts on how useful Anubis really is. Combined with comments I read elsewhere about scrapers starting to solve the challenges, I'm afraid Anubis will be outdated soon and we need something else.

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[–] 9 points 1 year ago* (15 children)

That's the great thing about Anubis: it's not client-side. Not entirely anyways. Similar to public key encryption schemes, it exploits the computational complexity of certain functions to solve the challenge. It can't just say "solved, let me through" because the client has to calculate a number, based on the parameters of the challenge, that fits certain mathematical criteria, and then present it to the server. That's the "proof of work" component.

A challenge could be something like "find the two prime factors of the semiprime 1522605027922533360535618378132637429718068114961380688657908494580122963258952897654000350692006139". This number is known as RSA-100, it was first factorized in 1991, which took several days of CPU time, but checking the result is trivial since it's just integer multiplication. A similar semiprime of 260 decimal digits still hasn't been factorized to this day. You can't get around mathematics, no matter how advanced your AI model is.

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  • [+] -8 points 1 year ago (14 children)

    @rtxn I don’t understand how that isn’t client side?

    Anything that is client side can be, if not spoofed, then at least delegated to a sub process, and my argument stands

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  • [–] 9 points 1 year ago (8 children)

    Please, explain to us how you expect to spoof a math problem that you have to provide an answer to the server before proceeding.

    You can math all you want on the client, but the server isn't going to give you shit until you provide the right answer.

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  • [+] -7 points 1 year ago (7 children)

    @Passerby6497 I really don’t understand the issue here

    If there is a challenge to solve, then the server has provided that to the client

    There is no way around this, is there?

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  • [–] 6 points 1 year ago (6 children)

    You're given the challenge to solve by the server, yes. But just because the challenge is provided to you, that doesn't mean you can fake your way through it.

    You still have to calculate the answer before you can get any farther. You can't bullshit/spoof your way through the math problem to bypass it, because your correct answer is required to proceed.

    There is no way around this, is there?

    Unless the server gives you a well-known problem you have the answer to/is easily calculated, or you find a vulnerability in something like Anubis to make it accept a wrong answer, not really. You're stuck at the interstitial page with a math prompt until you solve it.

    Unless I'm misunderstanding your position, I'm not sure what the disconnect is. The original question was about spoofing the challenge client side, but you can't really spoof the answer to a complicated math problem unless there's an issue with the server side validation.

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  • [+] -7 points 1 year ago (5 children)

    @Passerby6497 my stance is that the LLM might recognize that the best way to solve the problem is to run chromium and get the answer from there, then pass it on?

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  • [–] 7 points 1 year ago

    Anubis has worked if that's happening. The point is to make it computationally expensive to access a webpage, because that's a natural rate limiter. It kinda sounds like it needs to be made more computationally expensive, however.

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  • [–] 6 points 1 year ago (1 child)

    Congrats on doing it the way the website owner wants! You're now into the content, and you had to waste seconds of processing power to do so (effectively being throttled by the owner), so everyone is happy. You can't overload the site, but you can still get there after a short wait.

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  • [–] 1 point 1 year ago

    That solution still introduces lots of friction. At the volume and rate that these bots want to be traversing the internet, they probably don’t want to be fully graphically rendering pages and spawning extra browser processes then doing text recognition to then pass on to the LLM training sets. Maybe I’m wrong there, but I don’t think it’s that simple and actually just shifts solving the math challenge horizontally (i.e., in both cases, the scraper or the network the scraper is running on still has to solve the challenge)

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  • [–] 6 points 1 year ago* (4 children)

    It's not client-side because validation happens on the server side. The content won't be displayed until and unless the server receives a valid response, and the challenge is formulated in such a way that calculating a valid answer will always take a long time. It can't be spoofed because the server will know that the answer is bullshit. In my example, the server will know that the prime factors returned by the client are wrong because their product won't be equal to the original semiprime. Delegating to a sub-process won't work either, because what's the parent process supposed to do? Move on to another piece of content that is also protected by Anubis?

    The point is to waste the client's time and thus reduce the number of requests the server has to handle, not to prevent scraping altogether.

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  • [–] -2 points 1 year ago (3 children)

    @rtxn validation of what?

    This is a typical network thing: client asks for resource, server says here’s a challenge, client responds or doesn’t, has the correct response or not, but has the challenge regardless

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  • [–] 4 points 1 year ago (2 children)

    THEN (and this is the part you don't seem to understand) the client process has to waste time solving the challenge, which is, by the way, orders of magnitudes lighter on the server than serving the actual meaningful content, or cancel the request. If a new request is sent during that time, it will still have to waste time solving the challenge. The scraper will get through eventually, but the challenge delays the response and reduces the load on the server because while the scrapers are busy computing, it doesn't have to serve meaningful content to them.

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  • [–] -5 points 1 year ago (1 child)

    @rtxn all right, that’s all you had to say initially, rather than try convincing me that the network client was out of the loop: it isn’t, that’s the whole point of Anubis

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