Executive Summary

Claude Fable 5.1, an AI model, cracked a 370‑year‑old cipher in 44 minutes, demonstrating its strength in tasks requiring extensive search and testing. The achievement, reported by Bruce Schneier on Security, highlights AI's potential in mathematical and cryptographic problem solving.

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Intelligence Metadata - Source Publisher: Schneier on Security - Published Date: 2026-09-09T11:08:26+00:00 - Category: research

Original Description: 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.

"It is one of the blessings of old friends that you can afford to be stupid with them."

— Ralph Emerson