Engineer reports GPT-6 Astra solved a Napoleonic cipher within six hours

SentinelOne engineer Carter Church says GPT-6 Astra deciphered a 217-year-old military message within six hours after receiving a single image and prompt. The letter contained 24 rows of numbers, letters and invented symbols and conveyed Napoleon's orders to General Auguste de Marmont. Church says the model used a partial key previously unconnected with the letter and developed a computational solver to recover the remaining text. He published a solution package with a script that regenerates the reading. Satoshi Tomokiyo, who maintains the Cryptiana historical cipher database, has marked the letter as solved. The result concerns one historical cipher aided by a surviving partial key.