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.

Tags: [AI](https://www.schneier.com/tag/ai/), [cryptography](https://www.schneier.com/tag/cryptography/), [history of cryptography](https://www.schneier.com/tag/history-of-cryptography/), [mathematics](https://www.schneier.com/tag/mathematics/) 

[Posted on September 9, 2026 at 7:08 AM](https://www.schneier.com/blog/archives/2026/09/claude-fable-solves-a-historical-cipher.html)			•
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