ChatGPT-6 Astra cracks 217-year-old Napoleonic cipher in six hours

SentinelOne engineer Carter Church used GPT-6 Astra to decipher a 1809 military dispatch from the headquarters of Eugène de Beauharnais that had gone unread for 217 years. The model solved it in about six hours from a single image and prompt, filling a gap in Napoleon's 1865 memoir.

• The cipher had sat unsolved on Cryptiana's list since 1809
• Astra cracked it in roughly six hours from one image
• The text completes a sentence missing from Napoleon's 1865 memoir
• Database curator Satoshi Tomokiyo marked the cipher solved