GPT-6 Astra solves 1809 Napoleonic letter, Cryptiana confirms the crack
Astra read the scanned ciphertext, reconstructed the missing key and used simulated annealing to recover a military briefing; Cryptiana marked the cipher as solved, though five symbols remain uncertain.
GPT-6 Astra cracked a 217-year-old Napoleonic military cipher : - The encrypted letter dates to March 1809 and was sent to Napoleon’s marshal Auguste de Marmont, shortly before Austria invaded France’s sphere of influence in April. - Astra reportedly read the scanned 1,300-symbol ciphertext, reconstructed the missing key using historical material and ran a simulated-annealing solver to decode it. - The recovered message contains a military briefing on troop positions and Austrian movements, giving Marmont intelligence ahead of the campaign. - The proposed solution was reviewed by Satoshi Tomokiyo of Cryptiana, who marked the previously unsolved cipher as solved, although five symbols remain uncertain.