Cyphral Distich

A 370-year-old historical cipher solved by AI

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Description

Claude Fable 5.1 successfully decoded Sir Thomas Urquhart’s Cyphral Distich and Cyphral Octastich, unsolved cryptograms dating back to 1652. The model correctly identified that the key was the book itself, using word indices to recover a Royalist prayer for King Charles II, a solution that had eluded human cryptanalysts for centuries.

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Details

Why this is interesting: Solved a famous 370-year-old cipher listed among the top 50 unsolved cryptograms, demonstrating novel AI persistence…
Built with: Fable 5.1 GPT-5.6 Sol K2.7 Code Fable 5 North Mini Code
Links: vals.ai
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Tags: #cryptography #historical #cipher-solver

Discovered: X
First posted: X · Sep 1, 2026
Listed: Added 14d ago
Build: Strong
Models: Strong

Cyphral Distich

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Cyphral Distich

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