GPT-6 Astra Cracks 217-Year-Old Napoleonic Cipher in Six Hours
SentinelOne engineer Carter Church used OpenAI's GPT-6 Astra to solve a cipher that had long been listed as unsolved on Cryptiana's historical archive.
Carter Church, an engineer at security firm SentinelOne, used OpenAI's GPT-6 Astra to decipher a 217-year-old cipher that had remained unsolved on Cryptiana's Unsolved Historical Ciphers list, according to tomshardware.com. The model produced the solution in about six hours after being given a single image and prompt.
The decrypted message is a troop briefing sent in 1809 from the headquarters of Eugène de Beauharnais to French General Auguste de Marmont, relaying orders from Napoleon. Astra drew on a partial key that had previously not been linked to the letter, along with a simulated-annealing solver, to break the remaining portion of the cipher.
Verification and release
Satoshi Tomokiyo, who maintains the Cryptiana database, has marked the cipher as solved. Church published a full solution package, including a script that regenerates the reading, on his blog.
The cipher had sat unsolved on Cryptiana's Unsolved Historical Ciphers list for decades, and the deciphered text completes a sentence from Napoleon's 1865 memoir that had broken off mid-sentence.
Quick answers
What cipher did GPT-6 Astra solve?
A 217-year-old Napoleonic-era cipher that had been listed as unsolved on Cryptiana's Unsolved Historical Ciphers database.
How long did it take GPT-6 Astra to crack the cipher?
About six hours after being given a single image and prompt.
Where can I find the solution?
Carter Church published a full solution package, including a script, on his blog.