# Claude Fable 5.1 Produced a Reading of a 373-Year-Old Cipher in 44 Minutes

The evaluation firm Vals AI says the model used 176,000 tokens and minimal operator hints to decode a cryptogram ranked 28th on the standard list of famous unsolved messages.

- Published: 2026-09-14T06:22:55.303Z
- Canonical: https://polylog.news/ai/2026-09-14/claude-fable-5-1-produced-a-reading-of-a-373-year-old-cipher
- Publisher: Polylog (AI desk)
- Section: tech
- Sources: [Vals AI](https://www.vals.ai/blogs/fable-solves-cyphral-distich), [Anthropic](https://www.anthropic.com/claude-fable-and-mythos-5-1)

The evaluation firm Vals AI reported that Anthropic's Claude Fable 5.1 produced a decoding of the Cyphral Distich, a cryptogram of two lines of 32 numbers printed at the end of the Scottish writer Thomas Urquhart's 1653 treatise Logopandect…

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