{"slug": "ai-just-cracked-two-nazi-enigma-messages-that-stumped-codebreakers-for-decades", "title": "AI just cracked two Nazi Enigma messages that stumped codebreakers for decades", "summary": "OpenAI's GPT-6 Astra and Anthropic's Claude Opus 5 each decrypted a previously unbroken Second World War German Enigma message, with both solutions verified by Frode Weierud, the retired electrical engineer who runs the Crypto Cellar archive. Developer Carter Leffen had GPT-6 Astra decode an 82-character radio message a German soldier encrypted on July 10, 1941 and listed as unsolved since 2005, a task the model completed in roughly ten hours, while cybersecurity executive Jack Willis used Claude Opus 5 on September 21 to break a different unsolved message. Weierud told TechCrunch that what GPT-6 Astra achieved in two days \"would take a human researcher weeks or even months,\" and seven unbroken Enigma messages remain in the collection, plus one whose plaintext is known but whose code is still uncracked.", "body_md": "An Enigma cipher machine from the Swiss Army’s cryptography collection (illustrative). Image: [Rama](https://commons.wikimedia.org/wiki/File:Enigma-IMG_0487-black.jpg) / Wikimedia Commons, CC BY-SA 2.0 FR, cropped\n\nAlan Turing’s most famous puzzle has a new set of solvers. Two frontier AI models, OpenAI’s GPT-6 Astra and Anthropic’s Claude Opus 5, have each cracked a German Enigma message from the Second World War that had resisted every attempt to break it for decades, [TechCrunch reports](https://techcrunch.com/2026/09/25/astra-and-opus-just-passed-turings-other-test/). Both solutions have been checked by the expert who keeps the archive they came from.\n\n## An 83-year-old radio message\n\nThe first came from Carter Leffen, a developer, who asked GPT-6 Astra to search a database of Enigma messages for one that had never been broken and decode it. It picked an 82-character radio message a German soldier encrypted on July 10, 1941, which had been listed as unsolved since 2005.\n\nAstra cracked it in roughly ten hours, [The Decoder reports](https://the-decoder.com/openais-gpt-6-astra-decrypts-a-nazi-radio-message-in-ten-hours-that-went-unsolved-for-83-years/). It did its own archive research for clues, built a simulator of the Enigma machine, and used a famous weakness of the design: Enigma never encrypts a letter as itself. A message decrypted from the same day mentioned the town of Rosenow, and when the model lined that word up in the right place, the rest came out as readable German. The message asked for marching orders and an immediate radio reply.\n\n## Claude breaks a second one\n\nOn September 21, Jack Willis, a cybersecurity executive who works with Anthropic, used Claude Opus 5 to break a different unsolved message. According to TechCrunch, Willis gave the model much more guidance than Leffen did, and Claude used the known signature of a particular German officer’s name to get in.\n\nThat leaves seven unbroken Enigma messages in the collection, plus one where the plaintext is known but the code itself still hasn’t been cracked.\n\n## ‘Weeks or even months’\n\nBoth solutions were checked by Frode Weierud, a retired electrical engineer who runs Crypto Cellar, the archive of intercepted wartime messages that the unsolved ones came from. He told TechCrunch he was in “awe”:\n\nGPT–6 Astra is behaving like a very professional cryptanalyst and archive researcher. What it achieved in two days would take a human researcher weeks or even months.\n\nFrode Weierud, Crypto Cellar\n\nHe added that he had personally “spent several weeks researching the Bundesarchiv files GPT–6 Astra refers to.” Leffen, meanwhile, says he spent far more effort building a website explaining the puzzle than on cracking it, with AI agents doing the analysis, coding and checking while he steered.\n\n## Why it matters\n\nThese messages won’t change the history of the war, but they show AI doing the slow, careful detective work of a specialist, from archive research to building its own tools, in hours rather than months. It’s the same pattern as [Claude’s physics record this week](https://madrobot.blog/2026/09/26/claude-nine-loops-physics-record-scattering-amplitude/): problems that looked out of reach mostly needed patience and effort, which AI now supplies cheaply.\n\n*Sources: [TechCrunch](https://techcrunch.com/2026/09/25/astra-and-opus-just-passed-turings-other-test/), [The Decoder](https://the-decoder.com/openais-gpt-6-astra-decrypts-a-nazi-radio-message-in-ten-hours-that-went-unsolved-for-83-years/).*", "url": "https://wpnews.pro/news/ai-just-cracked-two-nazi-enigma-messages-that-stumped-codebreakers-for-decades", "canonical_source": "https://madrobot.blog/2026/09/26/ai-cracks-unsolved-enigma-messages-gpt-6-astra-claude-opus/", "published_at": "2026-09-26 07:14:00+00:00", "updated_at": "2026-09-27 09:59:15.478406+00:00", "lang": "en", "topics": ["artificial-intelligence", "large-language-models", "ai-research", "ai-agents"], "entities": ["OpenAI", "GPT-6 Astra", "Anthropic", "Claude Opus 5", "Carter Leffen", "Jack Willis", "Frode Weierud", "Crypto Cellar"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/ai-just-cracked-two-nazi-enigma-messages-that-stumped-codebreakers-for-decades", "markdown": "https://wpnews.pro/news/ai-just-cracked-two-nazi-enigma-messages-that-stumped-codebreakers-for-decades.md", "text": "https://wpnews.pro/news/ai-just-cracked-two-nazi-enigma-messages-that-stumped-codebreakers-for-decades.txt", "jsonld": "https://wpnews.pro/news/ai-just-cracked-two-nazi-enigma-messages-that-stumped-codebreakers-for-decades.jsonld"}}