The MVUEH Breakthrough: OpenAI GPT–6 Astra Deciphers a 20-Year Enigma Mystery

On September 15, 2026, Carter Leffer approached me to verify a stunning achievement: the successful decryption of the German Army Enigma message known as MVUEH, dated July 10, 1941.

📜 Historical Context of the Message

The transmission was dispatched by a radio station utilizing the tactical callsign 2ny and was received by the SS-Totenkopf Quartiermeister, Ib. The log indicates the message arrived at 17:30 on the date mentioned.

For over two decades—specifically since 2005—this particular cipher had remained an impenetrable wall for cryptanalysts.

Previous Attempts

In June 2017, Alex Shovkoplyas managed to crack another message from that same day (Nr. 173, SIPVX). While a victory, it provided a false lead for MVUEH.

Despite the SIPVX break, the resulting key was useless for MVUEH because the latter utilized a completely different configuration.

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🤖 The AI's Analytical Process

The most shocking aspect of this discovery is that GPT–6 Astra performed the entire operation autonomously. Carter Leffer simply tasked the AI with exploring the unsolved Enigma messages hosted on the Crypto Cellar Research website.

The AI's Workflow

To achieve this, the AI didn't just guess; it engineered its own tools. It wrote custom software in Python and C++ to simulate the Enigma machine and the "Bombe" decryption device.

Example of the AI's simulated logic:

// Simplified representation of the AI's Enigma rotor logic
void rotateRotor(int &position, int notch) {
    position++;
    if (position == notch) {
        triggerTurnover(); // Handling the rare left-wheel turnover
    }
}

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🔍 Technical Nuances & Findings

The break revealed several critical details that had previously eluded humans:

• Plaintext Correlation: The content of MVUEH is nearly identical to SIPVX.
• Human Error: The decryption exposed a typo by the original German operator: Bitte $\rightarrow$ Btte.
• Signatures: The name Waschbusch appeared as a repeated signature in the SIPVX message.
• Transcription Errors: The AI identified that the original transcription of the MVUEH ciphertext contained mistakes.
• The Turnover: The break confirmed that the Enigma's left-hand wheel turned over at the $72^{nd}$ letter.

Mathematically, the complexity of a turnover can be represented as a shift in the state space: $\text{State}_{n+1} = f(\text{State}_n, \text{Turnover}_{72})$ This rare occurrence typically makes cryptanalysis significantly more difficult.

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🏛️ The "Digital Archivist" Behavior

Beyond mathematics, GPT–6 Astra acted as a professional historian. It discovered a note I had posted in July 2026 regarding new findings in the German Bundesarchiv (specifically messages from the Nachschubführer of the SS-Totenkopf Division).

The AI's logs revealed a sophisticated research trail:

"Original-source access lead. The completed evidence pass traced the received corpus to a private collection and found concrete Bundesarchiv radio-message volumes, including RS 3–3/20a and RS 3–3/63b."

AI Research Checklist:

• Scan Crypto Cellar Research web page.
• Cross-reference Bundesarchiv file RS 3–3/20a.
• Cross-reference Bundesarchiv file RS 3–3/63b.
• Search for missing image of original no. 172.
• Analyze private collection leads.

The type of machine GPT-6 Astra simulated to break the code.

🏁 Final Reflections

The AI's ability to synthesize archival research with high-level cryptanalysis is breathtaking. It completed in two days what would typically require a human expert weeks or months of labor. As a veteran cryptanalyst, I am left in absolute awe of this capability.

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Updated: 19 September 2026, 08:41 UTC
Source: Frode Weierud, Crypto Cellar Research © 2026
License: CC BY-NC-SA 4.0