Two days ago, GPT-6 Astra broke a yet unsolved German Army Enigma message from 1941. Amazingly Astra was able to autonomously:
- Search historical archives
- Compare uncertain letters
- Find contextual clues
- Build an Enigma simulator
- Write cryptanalysis code
- Run parallel experiments
- Test competing keys
- Recover the plaintext
- Cross-check the results
1/n
Carter Leffen
@carterleffen
…eh-enigma-solved.carterl.chatgpt.site
GPT-6 Astra Extra High found the solution in roughly 10 hours.
“Please specify the route of march. I am in Rosenow, Rosenow. Immediate reply by radio.”
2/n
GPT-6 Astra Extra High found the solution in roughly 10 hours.
“Please specify the route of march. I am in Rosenow, Rosenow. Immediate reply by radio.”
2/n
mvueh-enigma-solved.carterl.chatgpt.site
MVUEH — An Enigma message recovered
Follow the two-day investigation that recovered the key to MVUEH, an authentic 82-letter Enigma message from July 1941, with source comparisons, experiments and reproducible checks.
2:05 AM UTC · Sep 17, 2026 · 54.8K Views
51349337
Carter Leffen
@carterleffen
I spent 99x more effort on building the website to describe the challenge and solution than any of my efforts on breaking the code. Astra also did all of the heavy lifting on building the site too! I just iterated with it over a few days.
3/n
3/n
2:05 AM UTC · Sep 17, 2026 · 49.4K Views
203378
Carter Leffen
@carterleffen
Special shoutout to Frode Weierud at cryptocellar.org for being so kind to review the results and provide feedback so quickly.
4/n
4/n
cryptocellar.org
Crypto Cellar Research
Crypto Cellar Research is dedicated to the history of cryptography, cipher machines and their simulation, cryptanalysis and other code breaking techniques.
2:05 AM UTC · Sep 17, 2026 · 47K Views
102039
Carter Leffen
@carterleffen
Check out the website to learn more about the challenge, see a virtual Enigma machine, in three.js no less.
…eh-enigma-solved.carterl.chatgpt.site
…eh-enigma-solved.carterl.chatgpt.site
mvueh-enigma-solved.carterl.chatgpt.site
MVUEH — An Enigma message recovered
Follow the two-day investigation that recovered the key to MVUEH, an authentic 82-letter Enigma message from July 1941, with source comparisons, experiments and reproducible checks.
2:09 AM UTC · Sep 17, 2026 · 42.1K Views
3321148