GPT-6 Astra Reportedly Cracks 217-Year-Old Napoleonic Cipher

GPT-6 Astra reportedly decoded a 217-year-old Napoleonic cipher in roughly six hours after starting with a single image and one prompt.
The 1809 message had remained undeciphered for more than two centuries. Astra reportedly transcribed around 1,300 handwritten symbols, identified a partial cipher key and built its own solver to decode the remaining text.
The model also cross-referenced surrounding historical letters to correct the message's published date. Historical cryptography researcher Satoshi Tomokiyo confirmed the solution and marked the cipher as solved.