A World War II transmission remained encrypted until GPT-6 Astra autonomously broke the cipher using a series of simulated experiments. The AI model searched historical archives and wrote its own attack code to recover the plaintext of a German Army Enigma message from 1941.

The operation took about 10 hours and involved the creation of an Enigma simulator to test competing keys and compare uncertain letters. This process allowed the system to identify contextual clues and cross-check results without human intervention to confirm the decrypted content.