On September 15, 2026, Carter Leffer contacted a researcher to request validation of a breakthrough by OpenAI's GPT-6 Astra in breaking the German Army Enigma message MVUEH. The message, dated July 10, 1941, and sent by radio station 2ny, had remained unsolved since 2005.
Model ReleasesGPT-6 AstraOpenAI
GPT-6 Astra Independently Breaks Unsolved 1941 Enigma Message MVUEH
According to Crypto Cellar Research, GPT-6 Astra autonomously identified the MVUEH message as a promising target after analyzing unsolved messages on the website. The model suspected a link between this message and another previously broken message, Nr. 173 (SIPVX), noting that the two were almost identical except for a twelve-letter difference.
To achieve the break, GPT-6 Astra developed its own Python and C++ software to function as an Enigma simulator and an Enigma Bombe—an electromechanical device used to decipher Enigma-encrypted messages. By using the repeated place name "ROSENOW ROSENOW" as a crib (a known or suspected piece of plaintext used for decryption), the AI successfully recovered the correct key and plaintext.
The analysis suggests the AI performed professional-level archival research, potentially referencing collections from the German Bundesarchiv. Researchers noted that the task, which would typically take a human researcher weeks or months, was completed by the AI in just two days.
Sources
- OpenAI GPT–6 Astra breaks Enigma message that has resisted solution since 2005 （Hacker News Frontpage, 2026-09-22）