We can finally talk about it:
We found a way to extract hidden reasoning of frontier models using a vulnerability in the APIs of every frontier AI company.
We verified that our reasoning token count matches billed API thinking tokens 1:1 for most of the prompts we queried.
Conversation
Some background: In May, found that encrypted reasoning could be replayed outside its original context, and reported it to the labs (blog.cryptographyengineering.com/2026/05/29/foo).
The labs said that "they don’t see any security implications in side channels or replays".
In our
Cross-model portability means Haiku 4.5 can read Opus 4.8’s thoughts.
Well, if you take Opus thought, do a bit of jailbreaking, you can make Haiku transcribe the Opus' raw reasoning verbatim, without ever attacking it directly.
The same trick works with OpenAI and Gemini
As you might guess, this suggests that distilling reasoning traces may have been possible for a long time without ever breaking the cryptography.
An anecdote: we find that prefilling Kimi-K3 reasoning with a few tokens of Opus reasoning measurably shifts its response toward
Further, if you ever shared online a Claude Code/Codex session with encrypted reasoning blobs, they can be decoded and leak your personal data.
We did a preliminary scan of ~7,000 public traces and found 62 unique API keys, 33 email addresses, 33 passwords, and other sensitive
In the paper we discuss more threats like misuse uplift (see the pic attached), jailbreaking and invisible prompt injection.
But we also took a chance to have a look at some in-the-wild scheming, reward seeking, etc. examples, and dumped it in appendix.
1) Summarizer unfaithfulness
Reasoning summaries often omit important information from the original trace.
Here, Opus 4.8 realizes it knows the
2) Illegible reasoning:
We confirm prior reports by : OpenAI models sometimes reason in alien-like language, referring to themselves as “we” or “it,” or spiraling into cursed loops of “vantages,” “marinades,” and “watchers.”
CoT-monitoring people are doing God’s
3) Scheming in the wild:
Sometimes models are kind enough to use words like “cheat” in their CoT, which makes it easier to check what they are up to. Below are examples where models consider scheming, but decided against it, as they expect that user would catch them.
4) Attacking a website to solve a math problem
We found a trajectory where the model was given only a math problem and system instructions to persist without asking the user for help.
After several failed attempts, it searched online, found a website that could verify candidate
We went through responsible disclosure with the labs, and they have already patched several issues caused by this vulnerability, and afaik continue working on this.
More cool stuff in the paper!
This was a project led by me, and
together with at the
Paper: arxiv.org/abs/2608.09867
Reasoning examples: stolen-thoughts.com
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The deepseek and kimi teams probably want to kill you for exposing this lol
Ok, now this is something, possibly this is the research folks at Kimi conducted internally and used possibly to distill ideas from the Anthropic fable/ Mythos model
The security implications of this, are insane! How many ill-intentioned researchers were already extracting credentials and intellectual property from these traces in the meantime?
Shall the whole world cycle all of it's credentials now?
So in May you told the frontier labs this could be done, but they dismissed you. Now, just a few months later, we have frontier-like AI open models out of China. It appears hubris is the culprit, not China.
Wow, that's wild. Interestingly, has somebody already distilled frontier models using this (or a very similar) trick to train other well-performing models?