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Claude Fable Solves a Historical Cipher

Claude Fable Solves a Historical Cipher

Claude Fable 5.1 solved a 370-year-old cipher in forty-four minutes.

This tracks with what I wrote about AIs doing mathematics: It’s good at things that involve lots of searching and testing.

EDITED TO ADD (9/14): I’m not sure if this result is correct . The blog comments have more discussion.

Tags: AI , cryptography , history of cryptography , mathematics

Posted on September 9, 2026 at 7:08 AM • 13 Comments