GPT‑6 Astra helps read a 217‑year‑old cipher letter to Napoleon's marshal
Carter Church says about six hours of model work transcribed and solved 1,300 cipher units, and the maintainer of the Cryptiana site has confirmed the solution, runtimewire reported.
Carter Church used OpenAI's GPT-6 Astra to solve a coded letter from March 1809 addressed to Napoleon's marshal Auguste de Marmont, runtimewire reported. Church says the model needed about six hours of execution to transcribe and decode it. The cipher had gone unread for 217 years, and Cryptiana now lists it as solved.
The hard part was the image, according to the report. The only copy is a reproduction of the letter in a 1969 journal, and it is poorly legible. Starting from a scan, the model read 1,300 cipher units, then found a published partial key covering 33 values. A solver it wrote assigned the remaining 155 distinct symbols.
https://x.com/kimmonismus/status/2105547846288073183
The recovered French text is a military briefing from the headquarters of Eugène de Beauharnais, covering troop positions and Austrian movements before Austria's April 1809 invasion. runtimewire says it fills out a sentence that breaks off in Napoleon's memoir. The model also cross-referenced other historical letters to correct the document's date, Church says.
Cryptiana's maintainer, Satoshi Tomokiyo, reviewed and confirmed the solution, runtimewire reported. Church flags five signs whose readings remain uncertain and has published the key, transcription and decoder script so others can check the work. runtimewire stresses this is AI-assisted archival research, not proof that a model authenticated the document on its own.