GPT-6 Astra helps decode a Napoleonic-era letter

Carter Church reports that GPT-6 Astra helped decode a 217-year-old cipher letter sent to one of Napoleon’s generals. According to his account, the task involved roughly six hours of model work.

The main difficulty was reportedly not the cipher itself, but extracting usable text from a barely legible historical scan. Astra transcribed about 1,300 cipher units from the image, located a published partial key and built a solver for the remaining code.

The result was then cross-referenced with historical letters to narrow down the document’s date. Cryptiana now lists the cipher as solved. These details reflect the published account of the project and would require independent review for full verification.