GPT-6 Astra decrypts 1941 Enigma message unsolved for 21 years

OpenAI’s GPT-6 Astra has successfully decrypted a 1941 German Enigma radio message, designated MVUEH, which had remained unsolved by cryptographers since 2005. The breakthrough was achieved in just two days after researcher Carter Leffen instructed the model to attempt to crack an unsolved message from the Crypto Cellar collection.

The model demonstrated significant autonomy by selecting the specific message, identifying a potential “crib” (a suspected piece of plaintext), and writing its own Enigma simulator and a software version of the “Bombe” search machine using Python and C++. The decryption revealed a routine military message regarding marching routes and a request for a radio reply.

Experts note that while the cryptographic methods used are well-established, the significance lies in the agentic nature of the AI. The model functioned by orchestrating multiple parallel expert agents to perform search, context, and review tasks, processing millions of potential keys to find the correct one. This highlights a shift toward AI agents that can independently build and deploy the tools necessary to solve complex, open-ended problems.