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Fable 5.1 Solves the Cyphral Distich, a 370-year-old cipher

The gist

Claude Fable 5.1 solved Sir Thomas Urquhart's 370-year-old Cyphral Distich in 44 minutes.
The 1653 cipher hid a royalist prayer, showing AI's strength at brute-force search.

How it unfolded

  1. Aug 31, 2026Vals AI published a blog post describing Claude Fable 5.1 solving Sir Thomas Urquhart's Cyphral Distich within a day, after 44 minutes and 176k tokens.
  2. Sep 9, 2026Bruce Schneier posted 'Claude Fable Solves a Historical Cipher,' stating Claude Fable 5.1 solved a 370-year-old cipher in forty-four minutes.
  3. Sep 13, 2026Asif Alli shared the Vals AI article on LinkedIn, calling it a signal of where AI tooling is heading; a Reddit r/hypeurls post and a Hacker News submission of the article also appeared.

Sources

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