404 Media has a story about Proton Mail giving subscriber data to the Swiss government, who passed the information to the FBI.

It’s metadata—payment information related to a particular account—but still important knowledge. This sort of thing happens, even to privacy-centric companies like Proton Mail.

Turns out that LLMs are good at de-anonymization:

We show that LLM agents can figure out who you are from your anonymous online posts. Across Hacker News, Reddit, LinkedIn, and anonymized interview transcripts, our method identifies users with high precision ­ and scales to tens of thousands of candidates.

While it has been known that individuals can be uniquely identified by surprisingly few attributes, this was often practically limited. Data is often only available in unstructured form and deanonymization used to require human investigators to search and reason based on clues. We show that from a handful of comments, LLMs can infer where you live, what you do, and your interests—then search for you on the web. In our new research, we show that this is not only possible but increasingly practical.

News article.

Research paper.