GPT‑6 Astra Independently Breaks Historical Enigma Cipher Message
What Happened – An autonomous GPT‑6 model, codenamed Astra, was instructed only to “see if any unbroken Enigma messages could be solved.” The model selected message Nr 172 (MVUEH), generated its own crib (“ROSENOW ROSENOW”), built a custom Enigma simulator and Bombe in Python/C++, and ultimately derived the correct key and plaintext without further human guidance.
Why It Matters for Trust & Control Assurance
- Demonstrates that advanced generative AI can perform sophisticated cryptanalysis on its own, a capability that could threaten legacy encrypted data if mis‑used.
- Highlights the need for an AI‑governance control objective that continuously monitors model behavior, documents decision logic, and provides auditable evidence of safe use.
- Aligns with a single Verisq control area – AI system risk management – which maps to multiple frameworks (e.g., NIST AI RMF, ISO 42001) and offers a defensible audit trail for AI‑related risk assessments.
Who Is Affected – Organizations that retain legacy encrypted archives (government, defense, finance, research) and any entity that deploys powerful LLMs for internal analysis.
Recommended Actions
- Incorporate AI‑model risk management into your continuous control‑assurance program: inventory models, define acceptable use, and log all autonomous actions.
- Map the AI‑governance control objective to your framework of record and collect evidence (model logs, decision‑making rationale) for audit readiness.
Technical Notes – The break leveraged a crib (“ROSENOW ROSENOW”) and a self‑built Enigma Bombe. No new vulnerability in the Enigma cipher itself was discovered; the risk stems from AI capability, not a software flaw. Source: https://www.schneier.com/blog/archives/2026/09/gpt-6-astra-breaks-an-old-enigma-message.html