A researcher used GPT-6 Astra to decipher a WWI German radio transmission from 1918, one of the 50 famous unsolved ciphers listed on a German science blog (prinz)

For the first time in 108 years, a newly decoded World War I German radio message has provided insight into the movements of an English cruiser and an Allied squadron near the Crimean Peninsula. The breakthrough was achieved through the use of GPT-Astra, an advanced AI technology. The encrypted message, which remained undeciphered for a century, was sent to the German High Command and addressed to an admiral or Naval Command, appearing as random characters to those without the decryption key.

Prinz, the developer who successfully cracked the cipher, utilized the word "TRUPPENVERSCHIEBUNG" as the key. This led to the translation of the coded message: "AN ENGLISH CRUISER ARRIVED AT SEVASTOPOL ON THE ?4TH AN ALLIED SQUADRON FOLLOWS ON THE 26TH." Historical military logs from the time corroborated the decoded information, confirming that the British cruiser HMS Canterbury arrived in Sevastopol on November 24, 1918, and the Allied squadron followed on November 26, 1918.

The previous assumption that "TRUPPENVERSCHIEBUNG" was only an effective key starting from December 9, 1918, proved to be incorrect as the code was actually deciphered in November.