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Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

scrapfly.dev

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Re: Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

#81

I think the screen resolution is also fingerprintable. That is why a browser should resize your window to a random size each time you visit a website.

browser report where your browser window (not position in tab) is even page itself never need to use it.

https://developer.mozilla.org/zh-CN/docs/Web/API/Window/scre...

Re: Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

#83
post #5

Thanks for the writeup, claude

[flagged]

I am not so paranoid, and I haven’t been working with AI, so my AI-dar is bad. But I keep reading technical writeups like this, then getting frustrated at the writing style or incomplete explanation – this one was more complete than most, though it was repetitive. Then I come read the HN comments, and I see that it was LLM-generated.

(To be fair, this one says so up top. Even so my eyes skipped over it.)

So I find the reaction helpful. I want to read posts in the best human style, but if the angry mob can’t motivate those, at least I can notice the pitchforks and torches, slap my forehead, and say, “Oh, that explains it.”

Re: Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

#84
post #44

Earlier quoted context omitted.

scraping, however, is not intrinsically a scam.

It is when you're doing it like the LLM companies are: at scale, to the degree that you're taking down my site, without my consent by masking your user-agent, for the purpose of stealing data I didn't authorize you to have.

I documented some crude methods that can stop most of that without a CDN. [1] There will be some false positives so I guess it depends on ones priorities which methods if any to implement or test on a throw-away test site. Not perfect, nothing is. I am watching hundreds of bots sending SYN's and the daemons are oblivious to them. The only method I have not played around with yet is #7 ssl fingerprinting.

There are additional methods I chose not to document such as limiting access to logged in accounts that require double-opting-in to acceptable use policies and terms of use, not that most scrapers would give a toss. That it too much whack-a-mole for me personally. That method requires progressively adding friction to account creation and that comes with some pros and cons.

[1] - https://nochan.net/b/Internet-Crap/20260606-How-To-Block-Som...

Re: Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

#85

Earlier quoted context omitted.

Sounds needlessly divisive. Why not criticize the content instead of the source or medium?

"The content is AI slop and not worth reading"

We all want signal and no noise, but complaining about whether or not it's noise is just more noise.

Re: Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

#86

What I don't get is that Chrome is hundreds of megabytes of just executable code, I assumed they statically linked half the userland. Also, I though tanh isn't a function, but an intrinsic emitted by the JS JIt that uses CPU instructions - which might be fingerprintable as well, but it's weird that for a math operation, you need to branch to a 'dlsym()' function.

Chrome is the only browser that preserve unused bit in value NaN through non JITed mode as far as I remember. And that bit become 0 when code get JITed.

Re: Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

#87
post #14

Can't we make fingerprinting illegal, as in, jailtime illegal? Would not solve everything but still help a lot.

I don't think it'd be possible to define fingerprinting narrowly enough to not also outlaw perfectly normal and legitimate usecases.

I'm not even sure I'd want to make it narrow. I'd start with:

"Information gained via side-channel for the purpose of correlating individuals."

But you'd have to add an enormous amount of legalese after that to make it ironclad. They'll start arguing "this isn't a side-channel", "we're targeting bots, not individuals", etc. You'd have to define every word in that sentence very carefully.

I'd make it sweeping. "Individual" can mean "person", "bot", "suspected bot", "AI agent", "a piece of autonomous or non-autonomous software", basically anything. The "side-channel" definition might get trickier, but I'd rather legit use-cases get burned than privacy get burned.

The OP was downvoted, but I agree. I think fingerprinting should be in the same criminal category as an illegal wiretap.

Re: Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

#89

Earlier quoted context omitted.

I never understood why fixed precision, and integer math isn't more popular. In engineering, we used fixed point all the time, it ran on much simpler hardware and the error is mathematically easy to model. IEEE 754 floats are not only suspect when it comes to theory, but are often outperformed with integers smaller than the mantissa (so less than 24 bits of int can beat a 32 bit float), when it comes to things like l…

I recommend pretty much everyone avoid fixed point and other float alternatives, barring exceptional cases after you've done your own numerical analysis, or you lack floating point hardware (rare these days). Yes, fixed point can use simpler hardware. That's also a completely irrelevant consideration for software. The vast majority of processors are optimized for floats now and some operations (e.g. division) are act…

> The vast majority of processors are optimized for floats now and some operations (e.g. division) are actually faster.

This seems backwards. Hardware is optimized for floats because people use floats. If people used fixed point, hardware would become optimized for that instead.

Given an equal number of transistors, I'm pretty sure fixed point would be a lot faster on equally optimized hardware for almost all operations.

Re: Since Chromium 148, Math.tanh is now fingerprintable to link underlying OS

#90
post #44

Earlier quoted context omitted.

It is when you're doing it like the LLM companies are: at scale, to the degree that you're taking down my site, without my consent by masking your user-agent, for the purpose of stealing data I didn't authorize you to have.

Something like Anubis in front of the server to protect it might be an option. It sucks that we have to resort to that yes, but it seems the least bad option currently (better than the entire internet going through Cloudflare at least).

You can just use one line of JS instead

https://fxgn.dev/blog/anubis

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