ChatGPT-6 Astra decodes 108-year-old WWI German cipher

Now 108 years after its transmission, an encrypted World War I German radio message has apparently been deciphered for the first time. The decoded and translated message relays information about the movements of an English cruiser and an Allied squadron near the Crimean Peninsula. Prinz, the developer who reckons they successfully decoded this covert WWI communication, used GPT-Astra to solve the cipher.

Prinz picked the code from a relatively famous list of 50 unsolved ciphers maintained by the German science blogging portal Scienceblogs.de. It was known to be “encoded using the ADFGVX method,” says the developer on their Substack.

Addressed to the German High Command and for the attention of an admiral or perhaps Naval Command, the ciphered message looks like gobbledygook, surely as intended. The German military at the time used a convoluted grid of letters that shuffled depending on the current keyword.

Astra solved the cipher using the word “TRUPPENVERSCHIEBUNG” as the key. This resulted in the decoded message: “EIN ENGLISCHER KREUZER EINLIEG X SEWASTOPOL X S4STEN X EIN GESCHWADER DER X ALLIIERTEN FOLGT 26STEN X.” Translated into English, we can at last understand that the radio message was the following alert: “AN ENGLISH CRUISER ARRIVED AT SEVASTOPOL ON THE ?4TH AN ALLIED SQUADRON FOLLOWS ON THE 26TH."

Astra also checked its work against military logs. The details about the cruiser’s arrival time aligned with the arrival of the British cruiser HMS Canterbury in Sevastopol, Crimea, on November 24, 1918. So the ‘?’ was perhaps a typo made in transmission. However, the Allied squadron's arrival date was spot on (November 26), according to the historical records Prinz checked.

GPT-Astra hypothesizes that previous attempts to decipher this German message failed because code sleuths made an incorrect assumption. Before this decoding feat, it was thought that the keyword “TRUPPENVERSCHIEBUNG” was used only as a key starting December 9, 1918. Remember, this message was transmitted on November 29 of that year.

This codebreaking feat is a cool result and a good example of Astra’s flexible problem-solving capabilities.

Mark Tyson is a news editor at Tom's Hardware. He enjoys covering the full breadth of PC tech; from business and semiconductor design to products approaching the edge of reason.