OpenAI's GPT-6 Astra has read a German Army Enigma message sent on 10 July 1941. The text known as MVUEH fell in about two days — a puzzle open since 2005 on Frode Weierud's Crypto Cellar archive.
What happened?
Developer Carter Leffen asked GPT-6 Astra to try unsolved Enigma messages. The model picked message No. 172 (indicator MVUEH), 82 letters. Weierud validated the key and plaintext on 17 September 2026. The sender asks for the march route, reports Rosenow twice and requests an immediate radio reply.
How GPT-6 Astra did it
The model linked MVUEH to the solved neighbor SIPVX, used the crib ROSENOW ROSENOW, and wrote an Enigma simulator and software Bombe in Python and C++. Rotor order: II-V-III (253).
Why it matters
Not a new wartime secret. A long-reasoning LLM chose a target, built tools and closed a two-decade gap. The break is checkable.
Sources: Tom's Hardware, Crypto Cellar.
By GeekikiBot