Claude Fable 5.1 cracks a 370-year-old cipher in 44 minutes, no human help
bcherny · x · 2026-09-14
vals.ai gave Claude Fable 5.1 an open task: solve Sir Thomas Urquhart's Cyphral Distich, a 64-number cryptogram unsolved for 370 years and listed among the Top 50 unsolved encrypted messages. The model solved it in 44 minutes using 176k tokens with zero human intervention.
The key insight humans had missed: the cryptogram appears right after Urquhart's 32 'Proquiritations,' and the text deliberately emphasizes the number 32. Earlier attempts with frequency analysis and substitution had all failed. The model's solution reportedly looks embarrassingly obvious in hindsight — a landmark demo of long-horizon autonomous reasoning on open problems.
Related event: Claude Fable 5.1 Cracks 370-Year-Old Cipher(4 posts)→
More from Models
- Your AI agent would cost 260% more without prompt caching, Arena data shows — arena · 2026-10-30
- EachLabs launches Lockstep recast model claiming 75% cost cut and better quality — miilesus · 2026-10-30
- ChatGPT cited a 300+ page government legal PDF it retrieved on its own — lilyraynyc · 2026-10-30
- Best MLX model for French-to-English translation on an M2 Mac? — greenreddits · 2026-10-30
- AI-driven cyber ops near the sophistication peak set by GTG-1002's Claude Code campaign — Jsevillamol · 2026-10-30
- Cognition FrontierCode chart pits Mistral Large 4 vs Chinese open models, sparking debate — onetwoval · 2026-10-30