On September 15, 2026, Carter Leffer validated OpenAI's GPT-6 Astra breaking a German Army Enigma message (MVUEH) from July 10, 1941, that had resisted solution since 2005. GPT-6 Astra autonomously analyzed unbroken messages, identified MVUEH as promising, and developed Enigma simulator software to execute a successful break using the crib ROSENOW, discovering the correct key and plaintext.