According to Tom's Hardware, cybersecurity engineer Carter Church used OpenAI's GPT-6 Astra to decipher a 217-year-old coded message that had been listed among Cryptiana's Unsolved Historical Ciphers for decades. Church says he gave the model a single image and a prompt, and it completed the entire multi-modal workflow in roughly six hours. The page contained a plain-text introductory line followed by 24 rows of numbers, letters, and invented symbols.
Church reports that the decoded text is not from Napoleon directly, but from the headquarters of Eugène de Beauharnais, Viceroy of Italy and Napoleon's stepson. It is a troop briefing sent to French General Auguste de Marmont, relaying Napoleon's orders. Marmont would have read it with an official military codebook of the era; since 1809, the message had apparently gone unread. Astra used a partial key previously unconnected with the letter, then cracked the rest with its own simulated-annealing solver, Church said.
The newly recovered text also fills in a missing fragment in Napoleon's 1865 memoir, which breaks off mid-sentence with "a handful of ..." and is completed by the cipher as "a gathering of rabble." Church says the solution is mechanically testable against the ciphertext, and Satoshi Tomokiyo, who maintains Cryptiana's Unsolved Historical Ciphers, has marked the letter as solved.