GPT-6 Astra AI Autonomously Breaks Historically Unbroken Enigma Message

GPT-6 Astra has achieved a significant milestone in autonomous cryptanalysis by breaking a historically unbroken Enigma message. The AI agent performed the entire process without human intervention in the technical execution, including the development of its own cryptographic simulation tools.

The break involved message Nr. 172 (MVUEH), which was part of a collection of unbroken messages hosted on the Crypto Cellar Research website. Researcher Carter Leffer directed the AI to attempt to solve the available messages.

Autonomous Software Development

To complete the task, GPT-6 Astra did not rely on pre-existing software. Instead, it developed its own Python and C++ code to create an Enigma simulator and a digital version of an Enigma Bombe—the electromechanical device originally designed to decipher German military communications.

The AI’s process began with an analysis of the unbroken messages. It identified message Nr. 172 as the most promising candidate and correctly suspected that its plaintext might be related to the plaintext of message Nr. 173 (SIPVX).

The ROSENOW Crib

After evaluating multiple approaches, the agent focused on using a specific “crib”—a known or suspected piece of plaintext. It identified the repeated place name “ROSENOW” as a likely candidate for the crib. By applying this to its custom-built Enigma Bombe software, the agent successfully identified the correct key and the corresponding plaintext for the MVUEH message.

Researchers are currently analysing the GPT-6 Astra execution logs to understand the specific reasoning and logic used during the break. This development demonstrates the increasing ability of autonomous agents to perform complex, multi-step technical tasks involving both software engineering and advanced mathematical cryptanalysis.