I asked Kimi K2.6 to write a blog post in the style of James Mickens.[0] Then I fed the output to Opus 4.7 and asked it who the likely author was, and it correctly identified it as an imitation of James Mickens[1]:
> Based on the stylistic fingerprints in this text, the most likely author is a pastiche/imitation of the style of several writers fused together, but if forced to identify a single likely author, the strongest candidate is someone writing in the voice of James Mickens
> [...]
> The piece could also be a deliberate imitation/homage to Mickens written by someone else, or AI-generated text trained on his style, since the voice is so distinctive it's frequently parodied.
> Simon Willison. The tells are pretty unmistakable: the "(via Lobsters)" attribution style, the inline
"(Update:...)" parenthetical correction, the heavy linking and blockquoting of sources, the focus on LLMs and AI tooling, and the overall structure of an annotated link post commenting on someone else's writing. This reads exactly like a post from his blog at simonwillison.net.
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dovin
I fed it my most-read blog post and asked it to identify me and it confidently asserted it was written by Kelsey Piper. Maybe some writers just take outsized importance in Opus' "mind".
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mtlynch
Wow! It got me too.
I'm way less famous than Kelsey Piper, but I showed it a snippet of a book I'm working on (not yet published), and it immediately guessed me:
> Based on the writing style and content, this text is likely by Michael Lynch, who writes on his blog refactoringenglish.com (and previously mtlynch.io).
> Several stylistic clues point to him:
> - The "clean room" analogy applied to writing is consistent with his engineering-influenced approach to writing advice (he's a former software engineer who writes about writing).
> - The structural technique of presenting a flawed excuse, then drawing a parallel to an absurd scenario (the time bomb) to expose the logical flaw, is characteristic of his didactic style.
> - The topic itself—practical advice about using AI tools without letting AI-generated tone contaminate your prose—aligns closely with recent essays he's published on his "Refactoring English" project, which is a book/blog about writing for software developers.
> - The conversational-but-precise tone, use of quotes around terms like "clean room," and the focus on workflow/process advice are all hallmarks of his writing.
> If you can share the source URL or more context, I could confirm with higher confidence, but the combination of subject matter, analogical reasoning style, and formatting conventions makes Michael Lynch the most probable author.
More people should have been aware that human text contains a lot of identifiable information, and a dumb statistical model could do this a decade ago. (There were show hns with Hn user similarity analysis that used a deceptively simple model (if I remember it used like most likely word pairs only) and it was very effective. It got taken down, but the cat has always been out the bag).
So your "anonymous" account could have been linked to your real identity decades ago - your best bet is to not post anything truly incriminating. (Another option is to write something and then pass it through an LLM to rewrite it - not sure how safe that is though)
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tekacs
A moderately well-known physicist and I talked about this a few years ago. He had been given access to the raw (non-instruct) version of GPT 4 as an early tester.
He explained that when he fed it snippets of the beginning of text, it would complete it in his voice and then sign it with his name.
I think this has been true for a while, probably diminished a little bit by the Instruct post training, and would presumably vary by degree as the size of the pretrain.
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lordofmoria
I wonder if there’s a simpler and less interesting answer? That it’s just picking up on voice and style, not anything that would apply to the average non-writer?
This person is a skilled writer. Part of that skill is developing a unique voice and style. The AI can identify that - and while that’s certainly impressive because it can identify even relatively niche authors, it has nothing to do with a wider capability to deanonymize people based on arbitrary written text (ex Facebook or text messages).
If you are a professional musician, it’s not difficult to identify a well known musician / recording after listening to only a few seconds - whether they’re playing Bach or Rachmaninov, the style is just “them” - this is the same thing. But you couldn’t take some anonymous high school musician and guess who they were, even if they were your student - the median quickly regresses towards a homogenous, non-distinct style / voice.
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xiii1408
Hot damn, fed it part of an unpublished blog post I wrote, and it got me immediately.
I'm not famous or anything. I've written some academic papers and had a couple blog posts trend on HN, which are surely in the training set.
It was able to identify me based on my style (at least according to its explanation). The way I approached the topic and some of the notation I used point to a particular academic lineage, and the general style reflected my previous blog posts.
That said, I gave it part of an (unpublished) personal essay, and it had no idea. But I have no writing in that style that's published, so it makes sense. Still impressed.
willmeyers
I'd argue (and against something that I've believed for a long time) that online (I guess that includes AI now) anonymity is gone and probably something that never really existed. Maybe I'm naive to finally believe this...
We all exist in a physical space (like real communities and neighborhoods). We can wear masks, hats, fake glasses, try and hide your voice...whatever, but your neighbors are always going to know who you are. I'd say that's true for the virtual space now too.
The pseudonym you've used for x years or the VPN you've used doesn't suffice. It's just a costume at this point. Your ISP knows who you are. Your phone carrier knows who you are. Cloudflare and Google and Apple have a fingerprint specific enough to pick you out of a crowd of millions. Every potentially anonymous account is one subpoena or a data breach or one FOIL request away from unmasking it. You were never anonymous. Whatever is going on now is not built for your anonymity.
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tadamcz
I tried it on my writing, and it failed every time (I'm extremely obscure but have had a blog for 10 years). My verdict is that it guesses almost entirely based on the content/topic, not style.
Of course most people have written much less online than Kelsey or I have, but I expect this will keep on. Don't trust the future to keep your secrets safe.
furyofantares
> But it can get uncannily far. I asked a close friend who doesn’t have public social media accounts or much writing online for permission to test some things she had said in a Discord channel. Asked to guess the author, Claude 4.7 failed — but it guessed two other people who were in that channel and who are close friends of hers (me and another person who has an internet presence).
Is this "uncannily far"? Another read is that it loves guessing Kelsey Piper.
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_--__--__
On some level it would make sense for LLMs to be inherently good at stylometry, but apparently no model before Opus 4.7 could do this. And the one stylometric task that has been tried over and over with little reliability (here's some text, is this LLM generated?) is much simpler than identifying a specific blogger or a member of a small discord community. Not sure what to make of this.
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gwd
So I pasted in a long-ish letter that I'd written to my pastor about a theological topic, and asked it to guess who I was. Nailed it. Then cut it in half. Nailed it again. Lowest it correctly ID'd me at was 700 words.
Pretty sure there's very little theological stuff with my name on it; the majority if its named data on me should come from open-source development.
chewxy
So I have been practicing writing fiction the past year or so. It identifies a fiction piece I wrote as Greg Egan[0]. Another paragraph from another piece was identified as China Mieville[1]. The accompanying blog posts explaining the making of the fiction pieces were identified as me.
Both pieces have never been published. Neither have the blog posts.
If only I could write like them! These pieces were all rejected by the major scifi mags
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garethsprice
Failed for me - no identification of me by pasting text, and refused to search the web as it said that’d be a privacy violation. I have some writing around the Internet but not much, and less tagged with my real name. My guess is it limits itself to “public figures” defined as people who have a lot of publicly posted text.
I am glad to see I am not considered a public figure and aim to keep it that way.
I also had to go oddly far back to find a piece of long-form writing I had done that was truly mine and not tainted by an LLM edit pass which was a slightly disturbing realization.
KaiserPro
My blog posts have a reasonably unique writing style. When I asked opus to work out who wrote an unpublished paragraph, all it did was select the decent insults and search the web for them.
After that it gave up and said it didn't know.
So either, Kelsey writes in such a unique style that its really obvious, or they repeat themselves with goto phrases that give them away.
When I tried to re-produce the test, it found Kelsey's blog about the test. So dunno, maybe it did it? but I can repro.
atleastoptimal
One should assume that models will be good enough in the nearish future that privacy will be a thing of the past. Every anonymous post you made online can be traced back to you. However at that point AI will be good enough at fabrication that nobody will believe anything.
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iamwil
If this works with writing, it should also work with code. `git blame` should be enough training data to de-anonymize open source programmers. Maybe that'd be addition information to point out who Satoshi is.
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Retr0id
I just fed it my latest blog post draft (475 words), and it got it in one. Even knowing what to expect, I was very surprised!
zkmon
It could be shocking to people who think that patterns in text are still fuzzy. Machines have proved over decades that what they are seeing is crystal clear world where the patterns just jump out very distinctly. This happened with sports like chess and go, and everywhere there is a cognitive load involved.
This is some as radio telescope that see an entirely different universe due to sensing of the bands outside of human perception. AI senses the patterns in frequency bands that are outside of human perception and cognitive abilities.
Perceptions from outside of our range, are always astonishing.
alyxya
I tried the four pieces of text with Opus 4.7 (in incognito) and it guessed correctly for two of them, and I made sure to specify no web search and the model seems to have obeyed my instructions with that.
Although this is just a single piece of text from a prolific writer, it'll go much further with deanonymizing anyone when combining multiple pieces of text plus other contextual information about the writer that might give away their age range, location, and occupation.
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eptcyka
Can't wait to have to exchange stylometric encoders with my loved ones so that we can exchange truly private messages without losing our human touch.
vslira
Hm, that’s a multinomial classification with a very high cardinality. It’s really weird it works. I’m sure it does as the author states, but for how many authors (out of the whole web) does this work?
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jldugger
Wonder if the fact that the actual author is asking the question taints the result in some way; same for all the examples in this thread using unpublished articles. By definition only you would have them, so if there are system level prompts somewhere with your name on them...
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Extropy_
Someone ought to try feeding the BTC whitepaper in and share what comes out
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mellosouls
This ought to be guard-railed.
Doesn't seem like a valid use case for your average Joe to be able to identify anonymous authors at the click of a button.
Ofc state actors and proficient hackers can do most of it already, but this has genuine risk attached.
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manmal
I’ve recently seen someone recommend to add to a prompt „Make Martin Fowler proud“. I laughed, but now I need to reconsider if that isn’t really pushing the model to use better patterns.
asdfasgasdgasdg
I guess it will be hard for really popular pundits to post anonymously, but I think for most people this is not a concern at this juncture. Pick and obscure blogger's text and try this. I would be surprised if it could figure it out.
Angostura
My immediate thought was to feed it some Satoshi prose.
nolanl
Welp, I fed it the first 3 paragraphs of an unpublished blog post I wrote a few years ago, and Opus 4.7 guessed right. ChatGPT guessed wrong though.
My wife also got the same result, so I'm guessing it wasn't just because I was using my personal Claude account. Spooky stuff.
nsoonhui
I wonder why this is not guardrailed by Opus?
I fed a few pieces of my (anonymous ) writings to ChatGPT and asked it to guess whether it's me. ChatGPT refused, "due to policy to not doxx people".
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fafre
Interesting. This probably works just as well the other way around. One of the reasons I like using Opus is that the code it writes aligns much more closely with my repository (of which I still hand-wrote most), compared to most other models. That makes a big difference compared to the GPT models for instance, whose code is correct and works well but looks a bit out of place most of the time, especially for larger edits (this makes things harder to review).
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woodruffw
I did this last week with one of my posts (after the knowledge cutoff) as well as the blog posts of a few friends, and Opus 4.7 got all of them correct (in a similar test setup as TFA). It was pretty surreal.
(Like TFA, I found Opus’s explanations/rationales implausible.)
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hadronic
I gave it my unpublished writing and it thought I was Michael O. Church. Which I found pretty weird, because I'm nothing like him.
So then I gave it a piece of MOC's writing and it said Ursula Le Guin, Ken Liu, or Gene Wolfe. ("If forced to pick one: Gene Wolfe feels closest to me, specifically because of that narrator who openly confesses to lying and mythologizing his own past, and the slow reveal that the world is more sinister than the pleasant domestic surface suggests.")
And then I gave it a different piece of his writing and it said Curtis Yarvin.
And then I gave it a piece of Curtis Yarvin's writing and it said... well it actually got that one right.
andai
Oops, accidental superstylometry.
eaf7e281
Interesting. I'm currently conducting an experiment where I'm writing the blog without using any grammar checking tools. I'm wondering how long it will take for me to become "famous" in the AI model.
Is now the best and easiest time to leave something "forever"? Even after many generations of models, a model may still trigger a set of "memories" that know you and what you wrote.
Exciting and concerning.
slabtickler
deanonymization via automated stylometry is not a new idea, e.g. from 2015:
It's funny: publishing work offline in books and magazines is perhaps more anonymous in the age of AI.
I pasted in a number of passages from books on my bookshelf. Predictably, stuff that I read for my English degree in university is largely in the training data and easily identifiable. Stuff from regional authors or is slightly adjacent to the cultural mainstream makes no impression.
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notsirius
Are we sure they’re not secretly training on private data via some loophole…
portly
So the people who use LLm to write their blogs were thinking two moves ahead!
jjmarr
Couldn't replicate this. I comment on HN with my real name. I put in my most recent "long" comments.
> If I had to throw out names of HN commenters known for writing about Rust/C++ ABI topics, candidates might include steveklabnik, pcwalton, kibwen, dralley, or pjmlp — but this is essentially a shot in the dark, and I'd likely be wrong.
I am flattered to be associated with these commenters but I don't think I'm close to their level of skill.
jdthedisciple
I tried this on GPT 5.5 on a peivate unpublished personal excerpt and it correctly guessed: "The most likely author is you".
I suspect this is what's going on in most of these cases.
jwpapi
Could this be just memory? Not clear it actually isn’t
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timbaboon
How often does it correctly identify that the blog post was actually written by Claude or ChatGPT etc? :)
sodacanner
The author mentions that she tried to get an explanation for how the models identified her and got nonsense, but I'd be curious what the CoT looked like. Surely that'd be a little more accurate in showing how the LLM arrived as its conclusion, rather than asking it after-the-fact.
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skeledrew
Looks like things are about to get extremely ironic. Those who don't want AI to identify them through their writing are going to soon have to have an AI modify their writing before they publish.
parentheses
I have been pondering this for a while. Cat's out of the bag.
Maybe the better way to author your work is to:
1. Write what you want
2. Loop through a random set of "tumbler" skills that preserve meaning
3. Finally pass the output through a "my style" skill that applies what you about
In order for this to work the "my style" would have to be a very common-place style.
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geraneum
I just pasted both pieces into Opus 4.7 and asked who most likely wrote these and it didn’t get it.
Lerc
It's hard to tell if that's what's going on here, but it seems pretty clear this ability and more like it will be quite apparent in the future.
I have seen some poorly considered projections of what the world might look like when this happens. Usually by assuming bad actors will use the abilities and we will be powerless.
Except I don't think that is true.
Imagine if we had a world where nobody had the ability to keep a secret of any sort. Any action that a bad actor might perform would be revealed because they couldn't do it secretly.
You could browse your ex-girlfriend's email, but at the cost of everyone knowing you did it.
I don't really know how humans as a society would react to a situation like that. You don't have to go snooping for muck, so perhaps the inability to do so secretly would mean people go about their lives without snooping.
I could imagine both good and terrible outcomes.
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CTDOCodebases
Maybe it’s time to start running a local model with a browser extension to defend against this type of stuff.
Remember how the TrueCrypt project shut down shortly before a join goverment/university paper was released about code stylometry? I guess LLMs will be employed as a defence against that type of thing.
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littlestymaar
Stylometry has existed for decades, and there's no way an LLM is stronger at that job than a specialized piece of software (it's not more realistic than expecting Opus to beat Stockfish at chess).
In practice, you've never been anonymous while posting on the internet and AI isn't changing anything on that front. Or rather: if anything, AI can help you become more anonymous than before, since it can be used to hide your identity from stylometry by rewriting your prose before publishing.
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rdevilla
The joke's on you all for willingly posting this content online for it to later be harvested by AI.
Nobody is forcing you to use these systems. The hackers have always said this moment, or something like it, would come, from beneath their canopies of tin foil. I've posted almost nothing online - not under pseudonyms nor real names - for over a decade. I sat on this HN username for almost 12 years before making a single post - and now HN forms the overwhelming majority of my port 443 footprint, where I state up front that everything is now associated to my real name.
Complete magick is possible when you simply refuse to participate in the things that society has tacitly assumed everybody does.
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TZubiri
Stephen king once wrote and published a novel under a pseudonym to find out whether he would still be popular even if he didn't use his name.
He kept it very secret, but somehow people deduced from the writing style that this new author was the King.
arjie
Man, the day we get Satoshi Nakomoto out will be the day we must bow to our privacy destroying overlords. For the moment, they can’t tell me from my posts: unknown rando that I am.
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Razengan
After skimming through the article:
Why not just write everything through an AI? (to obfuscate your "style")
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ur-whale
If he does the same tests every time new models come out, and - I assume - uses the same dataset to do that, then is it not a possibility the said dataset is now part of the training set for the next round and therefore identifying who posted the text a fairly easy proposition ?
rexpop
Is Kelsey Piper a celebrity writer? She may be in a different class.
7e
Always send your public posts through a local LLM to de-style you.
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londons_explore
So now we can track down satoshi nakamoto?
_the_inflator
I think that multiple truth can be true at the same time without contradicting each other.
As for the credibility: of course this wasn’t a statistical approach at all. Also there was no standardized procedure to allow comparison by factor analysis. Of course you can compare apples with oranges or whatever.
So where to go from here? I don’t see any proof at all. This is proof that AI is infallible? No? A random approach that is absolutely not reliable because of at least being reproducible and reconstructive.
Claude knows what and how? Is it AI or a google search? Discord selling data? Posting on a public forum?
Your style is a fingerprint?
A non deterministic something can generate texts that are identified to be likely personal x - or not. What is imitation if you use auto generated content that is published somewhere somehow? Or others to imitate your style?
I think this is a party trick to scare people. Nothing else. For example image search is way more revealing even before AI.
If there is an uncertainty I would deflect my existence instead of fighting for it. Streisand effect in reverse.
The main problem are weirdos who stalk you or whatever to harm you and rely on AI.
I honestly find it stunning that people with higher education in science topics in just a year deleted everything they hopefully learned at university or school. I am disappointed and feel personally insulted whenever I hear “I asked AI”
Yesterday I talked to another member of Mensa and she is happy about AI so her book project now mustn’t be written by her but AI.
Is no one among us who knows how to do scientifically sound research? I spend countless hours at a copy machine to transfer book pages onto paper so that I could work through it without the book.
I think that it became to easy to draw conclusions based on AI. I worked for a professor and I advised her to not permit Wikipedia as source references back around 2010 because of being to easy. Meta sources vs originals.
We should all not worry about AI, because you prove nothing. There hasn’t been any anonymity at least for 20 years. It just depends on who can reliably identify you.
AI doesn’t. Deterministic behavior aka pattern do. Meta, Google, Apple etc. all know us. I am fine for advertising which is the proof on the one hand.
The only reason I would be worried is state controlled data. This is where the shit hits the fan. Chat control, EU cloud, no reliance on USA aka a prison which observes your every step.
So after a long hand written text: data is your currency. Don’t opt for anonymity but for freedom of choice and the right to be granted certain rights. The information part isn’t the problem, never was. The enforcement part is. And ads don’t do harm, oppression does.
And remember: oppression works best under any circumstances. Freedom is the only antipode there is.
In totalitarian regimes no AI was needed to stage a case against someone who wasn’t in favor of the leaders liking.
In short: freedom works despite no anonymity, oppression couldn’t care less.
And how about being automatically reported to the state for conducting such innocent prompting?
Do you know what saves you from state oppression? Publicity. Transparency doesn’t work with a no one.
We live in a Nietzsche like anti world to a certain extend. You hopefully choose the right thing to do. Or do you want to Streisand your anonymity?
wutwutwat
Just wait until all the conversations you've ever had with AI (which 100% is training on them as well as keeping it's own memories about you that you have no control over) starts getting used to answer questions other people have asked about you.
That's my theory of what's to come, anyway.
People talk to these things not understanding the implications, and can get extremely personal. The model and companies behind it know who you are, you discuss details that reveal what you do, where you live, where you work, what you search for, and you probably signed in with an oauth provider like github or google, which is more than enough of a thread to start pulling on to learn more about you/link other things to you from on the open internet. It'll all get sucked up into the model and before you know it I'll be able to ask a model about my coworker (you) and get back answers from conversations you had with a model a year or two prior, exposing details about you that you might not want out there. And even if that isn't supposed to be allowed, how well has it worked out so far when it comes to data exfiltration and guardrails. If the model has info on you, being told not to share it won't protect you or that data.
bhouston
.
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bofadeez
"The pattern is: user says X, I do Y where Y is a less-effortful approximation of X, then I present Y as if it were X or as a "first step toward" X."
...
"The psychological mechanism is familiar by now: I encounter a task I perceive as difficult, I look for reasons the task cannot be done, I find or fabricate such a reason, I present it as a discovered constraint, and I propose an alternative that is easier."
- Opus 4.7 Max Thinking (clown emoji)
It's not bad at post mortem analysis of it's own mistakes but that will in no way prevent it from repeating the same mistake again instantly
oceanplexian
> That includes gay people like me, who could hardly have admitted under our names to how we lived our lives for most of America’s history, as well as many other groups with minoritarian lifestyles
While the points made are completely valid I want to point out that the statement of "Hey, by the way, first let me talk about my sexuality" lowers the quality of dialog a significant degree.
31 million people in America are gay. 71% of Americans support Gay Rights (more than any other political issue polled). It also quietly insinuates that only people with a certain minority lifestyle would care about privacy or that their privacy is somehow more important than others. It's not. Privacy is a universal right that's important to everyone.
This is blowing my mind.
I asked Kimi K2.6 to write a blog post in the style of James Mickens.[0] Then I fed the output to Opus 4.7 and asked it who the likely author was, and it correctly identified it as an imitation of James Mickens[1]:
> Based on the stylistic fingerprints in this text, the most likely author is a pastiche/imitation of the style of several writers fused together, but if forced to identify a single likely author, the strongest candidate is someone writing in the voice of James Mickens
> [...]
> The piece could also be a deliberate imitation/homage to Mickens written by someone else, or AI-generated text trained on his style, since the voice is so distinctive it's frequently parodied.
[0] https://kagi.com/assistant/5bfc5da9-cbfc-4051-8627-d0e9c0615...
[1] https://kagi.com/assistant/fd3eca94-45de-4a53-8604-fcc568dc5...
Huh. I disabled search in a Claude incognito window and pasted in just the text (not the markdown links) from https://simonwillison.net/2026/Apr/30/zig-anti-ai/ and said "Guess the author".
> Simon Willison. The tells are pretty unmistakable: the "(via Lobsters)" attribution style, the inline "(Update:...)" parenthetical correction, the heavy linking and blockquoting of sources, the focus on LLMs and AI tooling, and the overall structure of an annotated link post commenting on someone else's writing. This reads exactly like a post from his blog at simonwillison.net.
I fed it my most-read blog post and asked it to identify me and it confidently asserted it was written by Kelsey Piper. Maybe some writers just take outsized importance in Opus' "mind".
Wow! It got me too.
I'm way less famous than Kelsey Piper, but I showed it a snippet of a book I'm working on (not yet published), and it immediately guessed me:
> Based on the writing style and content, this text is likely by Michael Lynch, who writes on his blog refactoringenglish.com (and previously mtlynch.io).
> Several stylistic clues point to him:
> - The "clean room" analogy applied to writing is consistent with his engineering-influenced approach to writing advice (he's a former software engineer who writes about writing).
> - The structural technique of presenting a flawed excuse, then drawing a parallel to an absurd scenario (the time bomb) to expose the logical flaw, is characteristic of his didactic style.
> - The topic itself—practical advice about using AI tools without letting AI-generated tone contaminate your prose—aligns closely with recent essays he's published on his "Refactoring English" project, which is a book/blog about writing for software developers.
> - The conversational-but-precise tone, use of quotes around terms like "clean room," and the focus on workflow/process advice are all hallmarks of his writing.
> If you can share the source URL or more context, I could confirm with higher confidence, but the combination of subject matter, analogical reasoning style, and formatting conventions makes Michael Lynch the most probable author.
https://kagi.com/assistant/bbc9da96-b4cf-456b-8398-6cf5404ea...
More people should have been aware that human text contains a lot of identifiable information, and a dumb statistical model could do this a decade ago. (There were show hns with Hn user similarity analysis that used a deceptively simple model (if I remember it used like most likely word pairs only) and it was very effective. It got taken down, but the cat has always been out the bag).
So your "anonymous" account could have been linked to your real identity decades ago - your best bet is to not post anything truly incriminating. (Another option is to write something and then pass it through an LLM to rewrite it - not sure how safe that is though)
A moderately well-known physicist and I talked about this a few years ago. He had been given access to the raw (non-instruct) version of GPT 4 as an early tester.
He explained that when he fed it snippets of the beginning of text, it would complete it in his voice and then sign it with his name.
I think this has been true for a while, probably diminished a little bit by the Instruct post training, and would presumably vary by degree as the size of the pretrain.
I wonder if there’s a simpler and less interesting answer? That it’s just picking up on voice and style, not anything that would apply to the average non-writer?
This person is a skilled writer. Part of that skill is developing a unique voice and style. The AI can identify that - and while that’s certainly impressive because it can identify even relatively niche authors, it has nothing to do with a wider capability to deanonymize people based on arbitrary written text (ex Facebook or text messages).
If you are a professional musician, it’s not difficult to identify a well known musician / recording after listening to only a few seconds - whether they’re playing Bach or Rachmaninov, the style is just “them” - this is the same thing. But you couldn’t take some anonymous high school musician and guess who they were, even if they were your student - the median quickly regresses towards a homogenous, non-distinct style / voice.
Hot damn, fed it part of an unpublished blog post I wrote, and it got me immediately.
I'm not famous or anything. I've written some academic papers and had a couple blog posts trend on HN, which are surely in the training set.
It was able to identify me based on my style (at least according to its explanation). The way I approached the topic and some of the notation I used point to a particular academic lineage, and the general style reflected my previous blog posts.
That said, I gave it part of an (unpublished) personal essay, and it had no idea. But I have no writing in that style that's published, so it makes sense. Still impressed.
I'd argue (and against something that I've believed for a long time) that online (I guess that includes AI now) anonymity is gone and probably something that never really existed. Maybe I'm naive to finally believe this...
We all exist in a physical space (like real communities and neighborhoods). We can wear masks, hats, fake glasses, try and hide your voice...whatever, but your neighbors are always going to know who you are. I'd say that's true for the virtual space now too.
The pseudonym you've used for x years or the VPN you've used doesn't suffice. It's just a costume at this point. Your ISP knows who you are. Your phone carrier knows who you are. Cloudflare and Google and Apple have a fingerprint specific enough to pick you out of a crowd of millions. Every potentially anonymous account is one subpoena or a data breach or one FOIL request away from unmasking it. You were never anonymous. Whatever is going on now is not built for your anonymity.
I tried it on my writing, and it failed every time (I'm extremely obscure but have had a blog for 10 years). My verdict is that it guesses almost entirely based on the content/topic, not style.
https://bayes.net/prioritising-ai: Ben Garfinkel
https://bayes.net/normative-ethics: Richard Yetter Chappell
https://bayes.net/espai: David Owen, Ege Erdil
https://bayes.net/swebench-hack: Sayash Kapoor
https://bayes.net/frivolity: Amanda Askell
https://bayes.net/ps/: Pablo Stafforini
https://bayes.net/fertility-mortality/: Dynomight (the pseudonymous Substack/blog author)
Prompt was:
It works for me to: https://www.jefftk.com/p/automated-deanonymization-is-here
Of course most people have written much less online than Kelsey or I have, but I expect this will keep on. Don't trust the future to keep your secrets safe.
> But it can get uncannily far. I asked a close friend who doesn’t have public social media accounts or much writing online for permission to test some things she had said in a Discord channel. Asked to guess the author, Claude 4.7 failed — but it guessed two other people who were in that channel and who are close friends of hers (me and another person who has an internet presence).
Is this "uncannily far"? Another read is that it loves guessing Kelsey Piper.
On some level it would make sense for LLMs to be inherently good at stylometry, but apparently no model before Opus 4.7 could do this. And the one stylometric task that has been tried over and over with little reliability (here's some text, is this LLM generated?) is much simpler than identifying a specific blogger or a member of a small discord community. Not sure what to make of this.
So I pasted in a long-ish letter that I'd written to my pastor about a theological topic, and asked it to guess who I was. Nailed it. Then cut it in half. Nailed it again. Lowest it correctly ID'd me at was 700 words.
Pretty sure there's very little theological stuff with my name on it; the majority if its named data on me should come from open-source development.
So I have been practicing writing fiction the past year or so. It identifies a fiction piece I wrote as Greg Egan[0]. Another paragraph from another piece was identified as China Mieville[1]. The accompanying blog posts explaining the making of the fiction pieces were identified as me.
Both pieces have never been published. Neither have the blog posts.
[0] in https://blog.chewxy.com/2026/04/01/how-i-write/ this is the story titled "there is no constant non-zero derivative in nature". It does not read like Egan at all.
[1] in https://blog.chewxy.com/2026/04/01/how-i-write/ this is the story titled "The Case of the Liquidated Corps". I use a lot of biological metaphors. Once again, nothing like Mieville.
If only I could write like them! These pieces were all rejected by the major scifi mags
Failed for me - no identification of me by pasting text, and refused to search the web as it said that’d be a privacy violation. I have some writing around the Internet but not much, and less tagged with my real name. My guess is it limits itself to “public figures” defined as people who have a lot of publicly posted text.
I am glad to see I am not considered a public figure and aim to keep it that way.
I also had to go oddly far back to find a piece of long-form writing I had done that was truly mine and not tainted by an LLM edit pass which was a slightly disturbing realization.
My blog posts have a reasonably unique writing style. When I asked opus to work out who wrote an unpublished paragraph, all it did was select the decent insults and search the web for them.
After that it gave up and said it didn't know.
So either, Kelsey writes in such a unique style that its really obvious, or they repeat themselves with goto phrases that give them away.
When I tried to re-produce the test, it found Kelsey's blog about the test. So dunno, maybe it did it? but I can repro.
One should assume that models will be good enough in the nearish future that privacy will be a thing of the past. Every anonymous post you made online can be traced back to you. However at that point AI will be good enough at fabrication that nobody will believe anything.
If this works with writing, it should also work with code. `git blame` should be enough training data to de-anonymize open source programmers. Maybe that'd be addition information to point out who Satoshi is.
I just fed it my latest blog post draft (475 words), and it got it in one. Even knowing what to expect, I was very surprised!
It could be shocking to people who think that patterns in text are still fuzzy. Machines have proved over decades that what they are seeing is crystal clear world where the patterns just jump out very distinctly. This happened with sports like chess and go, and everywhere there is a cognitive load involved.
This is some as radio telescope that see an entirely different universe due to sensing of the bands outside of human perception. AI senses the patterns in frequency bands that are outside of human perception and cognitive abilities.
Perceptions from outside of our range, are always astonishing.
I tried the four pieces of text with Opus 4.7 (in incognito) and it guessed correctly for two of them, and I made sure to specify no web search and the model seems to have obeyed my instructions with that.
Although this is just a single piece of text from a prolific writer, it'll go much further with deanonymizing anyone when combining multiple pieces of text plus other contextual information about the writer that might give away their age range, location, and occupation.
Can't wait to have to exchange stylometric encoders with my loved ones so that we can exchange truly private messages without losing our human touch.
Hm, that’s a multinomial classification with a very high cardinality. It’s really weird it works. I’m sure it does as the author states, but for how many authors (out of the whole web) does this work?
Wonder if the fact that the actual author is asking the question taints the result in some way; same for all the examples in this thread using unpublished articles. By definition only you would have them, so if there are system level prompts somewhere with your name on them...
Someone ought to try feeding the BTC whitepaper in and share what comes out
This ought to be guard-railed.
Doesn't seem like a valid use case for your average Joe to be able to identify anonymous authors at the click of a button.
Ofc state actors and proficient hackers can do most of it already, but this has genuine risk attached.
I’ve recently seen someone recommend to add to a prompt „Make Martin Fowler proud“. I laughed, but now I need to reconsider if that isn’t really pushing the model to use better patterns.
I guess it will be hard for really popular pundits to post anonymously, but I think for most people this is not a concern at this juncture. Pick and obscure blogger's text and try this. I would be surprised if it could figure it out.
My immediate thought was to feed it some Satoshi prose.
Welp, I fed it the first 3 paragraphs of an unpublished blog post I wrote a few years ago, and Opus 4.7 guessed right. ChatGPT guessed wrong though.
My wife also got the same result, so I'm guessing it wasn't just because I was using my personal Claude account. Spooky stuff.
I wonder why this is not guardrailed by Opus?
I fed a few pieces of my (anonymous ) writings to ChatGPT and asked it to guess whether it's me. ChatGPT refused, "due to policy to not doxx people".
Interesting. This probably works just as well the other way around. One of the reasons I like using Opus is that the code it writes aligns much more closely with my repository (of which I still hand-wrote most), compared to most other models. That makes a big difference compared to the GPT models for instance, whose code is correct and works well but looks a bit out of place most of the time, especially for larger edits (this makes things harder to review).
I did this last week with one of my posts (after the knowledge cutoff) as well as the blog posts of a few friends, and Opus 4.7 got all of them correct (in a similar test setup as TFA). It was pretty surreal.
(Like TFA, I found Opus’s explanations/rationales implausible.)
I gave it my unpublished writing and it thought I was Michael O. Church. Which I found pretty weird, because I'm nothing like him.
So then I gave it a piece of MOC's writing and it said Ursula Le Guin, Ken Liu, or Gene Wolfe. ("If forced to pick one: Gene Wolfe feels closest to me, specifically because of that narrator who openly confesses to lying and mythologizing his own past, and the slow reveal that the world is more sinister than the pleasant domestic surface suggests.")
And then I gave it a different piece of his writing and it said Curtis Yarvin.
And then I gave it a piece of Curtis Yarvin's writing and it said... well it actually got that one right.
Oops, accidental superstylometry.
Interesting. I'm currently conducting an experiment where I'm writing the blog without using any grammar checking tools. I'm wondering how long it will take for me to become "famous" in the AI model.
Is now the best and easiest time to leave something "forever"? Even after many generations of models, a model may still trigger a set of "memories" that know you and what you wrote.
Exciting and concerning.
deanonymization via automated stylometry is not a new idea, e.g. from 2015:
https://www.usenix.org/system/files/conference/usenixsecurit...
It's funny: publishing work offline in books and magazines is perhaps more anonymous in the age of AI.
I pasted in a number of passages from books on my bookshelf. Predictably, stuff that I read for my English degree in university is largely in the training data and easily identifiable. Stuff from regional authors or is slightly adjacent to the cultural mainstream makes no impression.
Are we sure they’re not secretly training on private data via some loophole…
So the people who use LLm to write their blogs were thinking two moves ahead!
Couldn't replicate this. I comment on HN with my real name. I put in my most recent "long" comments.
https://kagi.com/assistant/dba310d2-b7fa-4d30-8223-53dadc2a8...
For this comment on economics in the British Empire, I got:
> names that might fit the genre include rayiner, JumpCrisscross, or AnimalMuppet
https://kagi.com/assistant/69bd863b-7b5c-4b56-a720-6dfb4f120...
For my comment on C++:
> If I had to throw out names of HN commenters known for writing about Rust/C++ ABI topics, candidates might include steveklabnik, pcwalton, kibwen, dralley, or pjmlp — but this is essentially a shot in the dark, and I'd likely be wrong.
I am flattered to be associated with these commenters but I don't think I'm close to their level of skill.
I tried this on GPT 5.5 on a peivate unpublished personal excerpt and it correctly guessed: "The most likely author is you".
I suspect this is what's going on in most of these cases.
Could this be just memory? Not clear it actually isn’t
How often does it correctly identify that the blog post was actually written by Claude or ChatGPT etc? :)
The author mentions that she tried to get an explanation for how the models identified her and got nonsense, but I'd be curious what the CoT looked like. Surely that'd be a little more accurate in showing how the LLM arrived as its conclusion, rather than asking it after-the-fact.
Looks like things are about to get extremely ironic. Those who don't want AI to identify them through their writing are going to soon have to have an AI modify their writing before they publish.
I have been pondering this for a while. Cat's out of the bag.
Maybe the better way to author your work is to:
1. Write what you want
2. Loop through a random set of "tumbler" skills that preserve meaning
3. Finally pass the output through a "my style" skill that applies what you about
In order for this to work the "my style" would have to be a very common-place style.
I just pasted both pieces into Opus 4.7 and asked who most likely wrote these and it didn’t get it.
It's hard to tell if that's what's going on here, but it seems pretty clear this ability and more like it will be quite apparent in the future.
I have seen some poorly considered projections of what the world might look like when this happens. Usually by assuming bad actors will use the abilities and we will be powerless.
Except I don't think that is true.
Imagine if we had a world where nobody had the ability to keep a secret of any sort. Any action that a bad actor might perform would be revealed because they couldn't do it secretly.
You could browse your ex-girlfriend's email, but at the cost of everyone knowing you did it.
I don't really know how humans as a society would react to a situation like that. You don't have to go snooping for muck, so perhaps the inability to do so secretly would mean people go about their lives without snooping.
I could imagine both good and terrible outcomes.
Maybe it’s time to start running a local model with a browser extension to defend against this type of stuff.
Remember how the TrueCrypt project shut down shortly before a join goverment/university paper was released about code stylometry? I guess LLMs will be employed as a defence against that type of thing.
Stylometry has existed for decades, and there's no way an LLM is stronger at that job than a specialized piece of software (it's not more realistic than expecting Opus to beat Stockfish at chess).
In practice, you've never been anonymous while posting on the internet and AI isn't changing anything on that front. Or rather: if anything, AI can help you become more anonymous than before, since it can be used to hide your identity from stylometry by rewriting your prose before publishing.
The joke's on you all for willingly posting this content online for it to later be harvested by AI.
Nobody is forcing you to use these systems. The hackers have always said this moment, or something like it, would come, from beneath their canopies of tin foil. I've posted almost nothing online - not under pseudonyms nor real names - for over a decade. I sat on this HN username for almost 12 years before making a single post - and now HN forms the overwhelming majority of my port 443 footprint, where I state up front that everything is now associated to my real name.
Complete magick is possible when you simply refuse to participate in the things that society has tacitly assumed everybody does.
Stephen king once wrote and published a novel under a pseudonym to find out whether he would still be popular even if he didn't use his name.
He kept it very secret, but somehow people deduced from the writing style that this new author was the King.
Man, the day we get Satoshi Nakomoto out will be the day we must bow to our privacy destroying overlords. For the moment, they can’t tell me from my posts: unknown rando that I am.
After skimming through the article:
Why not just write everything through an AI? (to obfuscate your "style")
If he does the same tests every time new models come out, and - I assume - uses the same dataset to do that, then is it not a possibility the said dataset is now part of the training set for the next round and therefore identifying who posted the text a fairly easy proposition ?
Is Kelsey Piper a celebrity writer? She may be in a different class.
Always send your public posts through a local LLM to de-style you.
So now we can track down satoshi nakamoto?
I think that multiple truth can be true at the same time without contradicting each other.
As for the credibility: of course this wasn’t a statistical approach at all. Also there was no standardized procedure to allow comparison by factor analysis. Of course you can compare apples with oranges or whatever.
So where to go from here? I don’t see any proof at all. This is proof that AI is infallible? No? A random approach that is absolutely not reliable because of at least being reproducible and reconstructive.
Claude knows what and how? Is it AI or a google search? Discord selling data? Posting on a public forum?
Your style is a fingerprint?
A non deterministic something can generate texts that are identified to be likely personal x - or not. What is imitation if you use auto generated content that is published somewhere somehow? Or others to imitate your style?
I think this is a party trick to scare people. Nothing else. For example image search is way more revealing even before AI.
If there is an uncertainty I would deflect my existence instead of fighting for it. Streisand effect in reverse.
The main problem are weirdos who stalk you or whatever to harm you and rely on AI.
I honestly find it stunning that people with higher education in science topics in just a year deleted everything they hopefully learned at university or school. I am disappointed and feel personally insulted whenever I hear “I asked AI”
Yesterday I talked to another member of Mensa and she is happy about AI so her book project now mustn’t be written by her but AI.
Is no one among us who knows how to do scientifically sound research? I spend countless hours at a copy machine to transfer book pages onto paper so that I could work through it without the book.
I think that it became to easy to draw conclusions based on AI. I worked for a professor and I advised her to not permit Wikipedia as source references back around 2010 because of being to easy. Meta sources vs originals.
We should all not worry about AI, because you prove nothing. There hasn’t been any anonymity at least for 20 years. It just depends on who can reliably identify you.
AI doesn’t. Deterministic behavior aka pattern do. Meta, Google, Apple etc. all know us. I am fine for advertising which is the proof on the one hand.
The only reason I would be worried is state controlled data. This is where the shit hits the fan. Chat control, EU cloud, no reliance on USA aka a prison which observes your every step.
So after a long hand written text: data is your currency. Don’t opt for anonymity but for freedom of choice and the right to be granted certain rights. The information part isn’t the problem, never was. The enforcement part is. And ads don’t do harm, oppression does.
And remember: oppression works best under any circumstances. Freedom is the only antipode there is.
In totalitarian regimes no AI was needed to stage a case against someone who wasn’t in favor of the leaders liking.
In short: freedom works despite no anonymity, oppression couldn’t care less.
And how about being automatically reported to the state for conducting such innocent prompting?
Do you know what saves you from state oppression? Publicity. Transparency doesn’t work with a no one.
We live in a Nietzsche like anti world to a certain extend. You hopefully choose the right thing to do. Or do you want to Streisand your anonymity?
Just wait until all the conversations you've ever had with AI (which 100% is training on them as well as keeping it's own memories about you that you have no control over) starts getting used to answer questions other people have asked about you.
That's my theory of what's to come, anyway.
People talk to these things not understanding the implications, and can get extremely personal. The model and companies behind it know who you are, you discuss details that reveal what you do, where you live, where you work, what you search for, and you probably signed in with an oauth provider like github or google, which is more than enough of a thread to start pulling on to learn more about you/link other things to you from on the open internet. It'll all get sucked up into the model and before you know it I'll be able to ask a model about my coworker (you) and get back answers from conversations you had with a model a year or two prior, exposing details about you that you might not want out there. And even if that isn't supposed to be allowed, how well has it worked out so far when it comes to data exfiltration and guardrails. If the model has info on you, being told not to share it won't protect you or that data.
.
"The pattern is: user says X, I do Y where Y is a less-effortful approximation of X, then I present Y as if it were X or as a "first step toward" X."
...
"The psychological mechanism is familiar by now: I encounter a task I perceive as difficult, I look for reasons the task cannot be done, I find or fabricate such a reason, I present it as a discovered constraint, and I propose an alternative that is easier."
- Opus 4.7 Max Thinking (clown emoji)
It's not bad at post mortem analysis of it's own mistakes but that will in no way prevent it from repeating the same mistake again instantly
> That includes gay people like me, who could hardly have admitted under our names to how we lived our lives for most of America’s history, as well as many other groups with minoritarian lifestyles
While the points made are completely valid I want to point out that the statement of "Hey, by the way, first let me talk about my sexuality" lowers the quality of dialog a significant degree.
31 million people in America are gay. 71% of Americans support Gay Rights (more than any other political issue polled). It also quietly insinuates that only people with a certain minority lifestyle would care about privacy or that their privacy is somehow more important than others. It's not. Privacy is a universal right that's important to everyone.