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

https://scrapfly.dev/posts/browser-math-os-fingerprint/
127•joahnn_s•1h ago•52 comments

Tiny Emulators

https://floooh.github.io/tiny8bit-preview/index.html
89•naves•2h ago•3 comments

So you want to learn physics (second edition, 2021)

https://www.susanrigetti.com/physics
20•azhenley•4d ago•3 comments

Claude Code sends 33k tokens before reading the prompt; OpenCode sends 7k

https://systima.ai/blog/claude-code-vs-opencode-token-overhead
356•systima•4h ago•200 comments

Migrating a production AI agent to GPT-5.6: 2.2x faster, 27% cheaper

https://ploy.ai/blog/migrating-a-production-ai-agent-to-gpt-5-6
74•brryant•5h ago•15 comments

Irish datacenters now guzzle 23% of the country's electricity

https://www.theregister.com/on-prem/2026/07/11/irish-datacenters-now-guzzle-23-of-the-countrys-el...
127•Bender•2h ago•79 comments

Ask HN: What Are You Working On? (July 2026)

19•david927•1h ago•28 comments

Old and new apps, via modern coding agents

https://terrytao.wordpress.com/2026/07/11/old-and-new-apps-via-modern-coding-agents/
387•subset•11h ago•111 comments

Mechanistic interpretability researchers applying causality theory to LLMs

https://cacm.acm.org/news/can-we-understand-how-large-language-models-reason/
66•adunk•4h ago•57 comments

Show HN: Adaptive Recall, persistent memory for AI assistants over MCP

https://www.adaptiverecall.com/
10•abratabia•1h ago•0 comments

Why write code in 2026

https://softwaredoug.com/blog/2026/07/09/write-code
74•softwaredoug•2d ago•124 comments

I love LLMs, I hate hype

https://geohot.github.io//blog/jekyll/update/2026/07/12/i-love-llms.html
256•therepanic•4h ago•139 comments

I Learned to Read Again

https://substack.magazinenongrata.com/p/how-i-learned-to-read-again
58•georgex7•4h ago•19 comments

Automation Without Understanding

https://arxiv.org/abs/2607.06377
76•root-parent•5h ago•37 comments

Kode Dot Programmable pocket device for makers, pentesters and geeks

https://kode.diy
7•iNic•1h ago•3 comments

LARP – Revenue infrastructure for serious founders

https://www.larp.website/
105•BerislavLopac•5h ago•26 comments

The State of MCP Security [pdf]

https://www.canopii.dev/State%20of%20MCP%20Security%202026.pdf
13•mavzer•1h ago•0 comments

The One-Step Trap (In AI Research)

http://incompleteideas.net/IncIdeas/OneStepTrap.html
34•jxmorris12•3h ago•7 comments

Against Usefulness

https://www.motivenotes.ai/p/against-usefulness
67•supo•4h ago•17 comments

Don't you mean extinct?

https://fabiensanglard.net/extinct/index.html
168•zdw•7h ago•95 comments

Deir El-Medina Strikes

https://en.wikipedia.org/wiki/Deir_el-Medina_strikes
49•mooreds•5d ago•6 comments

How to read more books

https://scotto.me/blog/2026-07-12-how-to-read-more-books/
224•silcoon•6h ago•128 comments

Flash-MSA: Accelerating Million-Token Training with Sparse Attention Kernels

https://nanduruganesh.github.io/flash-msa/
7•rawsh•1h ago•0 comments

The Seed Beneath the Snow

https://eli.li/the-seed-beneath-the-snow
13•surprisetalk•3d ago•1 comments

The shingles vaccine may reduce the risk of dementia

https://www.economist.com/leaders/2026/07/09/a-no-brainer-for-protecting-your-brain
189•saikatsg•7h ago•165 comments

Why study Diophantine equations?

https://hidden-phenomena.com/articles/modular
59•mb1699•6h ago•21 comments

Show HN: Zen Mode – a global focus mode for macOS

https://github.com/cabeen/zen-mode
8•cafebeen•1h ago•2 comments

Defining new Jax types with hijax

https://docs.jax.dev/en/latest/hijax_types.html
10•fhchl•2h ago•2 comments

Neocities: Create your own free website

https://neocities.org/
64•Tomte•2h ago•21 comments

Ghostel.el: Terminal emulator powered by libghostty

https://dakra.github.io/ghostel/
255•signa11•13h ago•48 comments
Open in hackernews

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

https://scrapfly.dev/posts/browser-math-os-fingerprint/
127•joahnn_s•1h ago

Comments

joahnn_s•1h ago
We noticed Chromium Math.tanh since v148 returned a different result, so we dig it - it's now a fingerprintable surface to retrieve the OS Chromium run on
dmitrygr•1h ago
Interesting reporting, marred by obvious llm-slop-sounding writing. "You are not building..., you are ..."
netsharc•34m ago
Why "slop-sounding"? It's definitely LLM slop.

Man, why the fuck don't they just make a powerpoint with bullet points if all the sentences are like that.

sjrd•1h ago
I guess that's one more good reason to push for correctly rounded transcendental functions. I recently learned that they're basically solved now. [1]

[1] https://arith2026.org/program.html (2nd keynote)

Retr0id•1h ago
Tangential, but wow do they really register a new domain for each year and renew it in perpetuity?
yzydserd•56m ago
arith2027.org taken, arith2028.org available.
Retr0id•56m ago
Well, there's an arbitrage opportunity if I ever saw one
voxl•41m ago
They would just choose a different domain name, it's not that important and the previous years tend to forward link anyway.
torginus•25m ago
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 loss of precision.
AlotOfReading•3m ago
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 actually faster.

The precision argument also falls apart. Any float with mantissa >= X+Y can get exactly the same results as a QX.Y fixed point. The float will actually perform better across the same range because you have to round it to perform like the fixed point. That means more precision, lower error, automatic normalization, better overflow behavior, a larger working range, etc. And it'll probably be just as fast, unless you're bottlenecked on memory bandwidth of inputs (unlikely). When you inevitably want an exp() or another special function, it's a heck of a lot easier to call libm than implement your own and it will perform better.

Floats are also much easier to get right for your coworkers that aren't numerical analysts.

Retr0id•1h ago
Thanks for the writeup, claude
_alternator_•1h ago
Yeah, interesting finding in the headline, the rest is just Claude.
ddtaylor•2m ago
I haven't been active on HN as much in the last few months. The community seems really fixated on calling content slop and detecting LLM usage in a paranoid way.
drnick1•1h ago
This is interesting, but even without relying on JS, most users are already fingerprintable by the combination of IP + user agent.
Aurornis•1h ago
> One tanh call on the right input is a per-OS signature. Claim macOS, return Linux math bits, and you have contradicted your own User-Agent.

They (or rather the LLM that wrote this) missed that this is possibly fingerprintable to browser version range, which is slightly more interesting. Most users aren't spoofing their user agent headers to be a different operating system. Most fingerprinting solutions aren't trying to infer your operating system, they only care about semi-unique things that show up.

It's an interesting finding. I wish they had taken some time to have a real person write it up. This is too heavily LLM written to ignore.

jeroenhd•57m ago
> Most users aren't spoofing their user agent headers to be a different operating system.

The people behind the LLM behind this blog post are. They're trying to pretend their robots are people to sell other websites' data to their customer. It's easier to pass bot detection gates if you pretend to be a physical machine running Windows or macOS than if you honestly admit you're using Linux on a VM.

reactordev•35m ago
The Internet is a cesspool of scams now
d1ss0nanz•27m ago
Always was.
pocksuppet•16m ago
scraping, however, is not intrinsically a scam.
jeroenhd•1h ago
Kind of a smart move by this company: write up an AI analysis of all fingerprinting techniques in hopes they get fixed after outrage so their scraping company can make more money. If it weren't for companies like this, fingerprinting wouldn't be so ubiquitous and the internet would be a better place in general.

I prefer articles like this coming from the other side of the battle (fingerprint.js and friends) because at least their motives are clear.

codedokode•33m ago
I disagree, fingerprinting is necessary to track humans and it will be used regardless of scrapers being there or not.
a-dub•58m ago
how hardened are modern browsers with respect to detecting underlying os? seems like there would be loads of gaps?
amelius•57m ago
Can't we make fingerprinting illegal, as in, jailtime illegal?

Would not solve everything but still help a lot.

chaboud•48m ago
I'd rather penalize the application than the technique. Windows was rumored to long have "quirks" that would do better things for apps that had bugs that the OS ended up fixing instead of the app.

Javascript systems have long had polyfills for varied browser feature comparability gaps.

Whether you agree with these, making probing detection via fingerprinting illegal would take away this lever. Making surreptitious tracking via fingerprinting illegal? Even for state actors?

Yeah, that's probably reasonable. If someone is going to wear a tracking collar in exchange for "free" services, a little disclosure makes sense.

Terr_•30m ago
Yeah, the problem is how the data is kept and abused afterwards.
akersten•41m ago
Why should it be illegal for me to recognize the way you walk into my store, even though you're wearing a mask and a trenchcoat? Some vague sense of indignation?

Yeah, tracking bad, I get it, but are whatever damages that kind of legislation would prevent (probably nothing measurable) really more important than fixing the easy, in our face social problems that politicians could instead be focusing on?

altcognito•34m ago
Because you don't have a right to know everything about me, follow me to my home, my purchasing preferences, and so on and so forth.
mrsssnake•40m ago
JavaScript was a mistake.
kristianp•6m ago
Who was it that said: "worse is better"?

This guy: https://dreamsongs.com/WorseIsBetter.html

qurren•39m ago
just inject this with your favorite JS injection plugin

    let oldTanh = Math.tanh;
    Math.tanh = x => oldTanh(x) + Math.random()/10000000;
sanxiyn•27m ago
The article addresses this: search for "No noise".
chjj•26m ago
it's elegant, but i prefer:

    Math.tanh = Math.random;
gruez•12m ago
Great, now you'll be outed as "hides fingerprint", which is probably more identifying than if you returned a normal value.
torginus•30m ago
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.
pocksuppet•4m ago
The x87 FPU implemented transcendental functions in microcode. Most instruction sets don't implement them. Mmicrocode is actually slower than software, since it doesn't get the benefit of things like branch prediction.
coppsilgold•21m ago
Even Tor Browser (/mullvad-browser) gave up trying to obscure the operating system, though arguably they shouldn't have. There appear to be too many fingerprinting vectors.
andai•8m ago
I am not the NSA, but on an unrelated note, this delights me!
fweimer•2m ago
Recent glibc uses the correctly rounded tanh from CORE-MATH, so it returns different values than what's quoted in the article. It's unclear today if it's possible to achieve reasonable performance for other transcendental functions with correct rounding, so other functions have their own unique fingerprints.
mplewis
•
13m ago
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.
acters•22m ago
It's sometimes easier to lie than to tell the truth, and being on Linux telling the truth gets me more scrutiny than those pretending to be legit.
joahnn_s•13m ago
You can only assert >148 at the moment, but there are better vectors to strictly assert the version by simply checking the addition of v8/blink on each chromium version (and since ~120 it's the case), so by checking if xxx is present and yyy is not present in js userland or css feature, the inference is 100% for the major version

And for the LLM writing, yes, it's written in the article and blog, it's not hidden or pretending, otherwise I would never publish an article due to lack of time, and I assume

comex•8m ago
This can be used to fingerprint version range, but so can a million other things. Browsers are constantly adding new features and fixing bugs, most of which can be detected from JavaScript.
lorecore•32m ago
> Why should it be illegal for me to recognize the way you walk into my store, even though you're wearing a mask and a trenchcoat?

If you have that right, the public should have the right to know you're doing this before they enter your store, so they can avoid it.

Same with the websites, they should, legally, have to say they're about to fingerprint you so that you can close your browser tab and never come back.

thepasch•30m ago
> Why should it be illegal for me to recognize the way you walk into my store

If you did it in just your store, that wouldn't be a problem. The correct analogy, however, is "why should it be illegal for me to attach a perfectly traceable and invisible air-tag to you when you enter my store, without your explicit consent, and subsequently follow and document your every movement no matter where you go, as long as that location has a business relationship with my store, and also my store is the most popular chain on the planet that has business relationships with basically any relevant business that exists." And I don't think the answer to this one shouldn't be particularly difficult to arrive at.

akersten•22m ago
Well it's not really an airtag, I don't "attach" anything to your browser when I check what its GPU can do.

That's just a description of you that I share with my other stores. Casinos, Target, Burger King, etc all do this when you get 86'd, for example.

kaladin-jasnah•13m ago
Isn't fingerprinting used across many different websites? Then the analogy would be a number of stores colluding to recognize the same person across all stores?

(I have no idea, I don't know too much about this)

charcircuit•6m ago
Which is famously done by casinos. But in practice many businesses big and small do share intelligence with each other about problematic customers who shoplift etc.
bloody-crow•38m ago
I don't think it'd be possible to define fingerprinting narrowly enough to not also outlaw perfectly normal and legitimate usecases.
codedokode•31m ago
Why don't you ask browser developers to stop adding features helping fingerprinting? Browsers even have some API for tracking ad clicks (attribution API or something) and user interests tracking API which nobody of the users needs.
joahnn_s•26m ago
The thing is that's not done on purpose and too hard to figure out how this has an impact underneath, if you read the v8 commit https://chromium.googlesource.com/v8/v8/+/c1486295ae5bcb0f8f... it's on a complete good faith
userbinator•9m ago
With companies like these, "plausible deniability" is more likely.