GPT-6 Astra Solves a WWI German Radio Cipher
The article presents a concrete cryptanalytic claim with a plausible key and historical cross-check, while the discussion centers on whether the model did genuine reasoning or merely selected a known key and identified an operator error, and on how quickly AI achievements get reclassified as unremarkable.
The brief
The author reports that GPT-6 Astra decoded a previously unsolved WWI German ADFGVX radio message from November 27, 1918, using the key TRUPPENVERSCHIEBUNG from J. Rives Childs's history of German military ciphers. The proposed plaintext says an English cruiser arrived at Sevastopol on the ?4th and an allied squadron followed on the 26th. The author notes the key was reportedly used starting December 9, 1918, so the earlier transmission date is unexplained, and says Astra checked the result against HMS Canterbury's logs showing arrival on November 24 and an allied squadron on November 26.
- ADFGVX uses a key-dependent table with row and column labels A, D, F, G, V, X; the article illustrates it with the key HOUSE and encodes PRINZ as FX GD DX FV VD.
- The message is from a set of German WWI radio messages, many already decoded, including by George Lasry, but over a dozen remained unsolved according to the article.
- Astra proposed the German plaintext: EIN ENGLISCHER KREUZER EINLIEG X SEWASTOPOL X S4STEN X EIN GESCHWADER DER X ALLIIERTEN FOLGT 26STEN X, translated as an English cruiser arriving at Sevastopol on the ?4th and an allied squadron following on the 26th.
- The claimed key is TRUPPENVERSCHIEBUNG, described on pages 214-215 of Childs; the article explains its alphabetical rearrangement and columnar transposition over 170 characters, with 19 columns and one shorter column.
- Astra's hypothesis is that TRUPPENVERSCHIEBUNG was used as the key starting December 9, 1918, while this message was transmitted earlier on November 27, 1918; the reason for the discrepancy is unknown.
- The author says Astra verified the plaintext against original ship logs: HMS Canterbury arrived in Sevastopol on November 24, 1918, and an allied squadron followed on November 26.
In the discussion
Commenters focus less on the cipher's mathematics than on whether the result demonstrates genuine model reasoning, whether the key was simply selected from a known list, and how to interpret AI capability claims.
Verification and possible fabrication
iltk asks whether the ship logs are online, raising the possibility that the model could have manufactured a fake key and matching message, though calling it unlikely; stalfie points to the article's image of the original log papers; JoshTriplett argues fabrication is unlikely because the key was documented as used for other messages.
Known key list and operator error
Legend2440 summarizes that the keys were known because the list was seized after the war, and that this message was missed because the German operator mistyped the key and used a key from the wrong day; ChatGPT therefore only had to pick the correct key from the list and identify the typo, not brute-force the entire key, and a sufficiently dedicated human analyst could have done the same.
Brute-force framing
msy asks whether the task is essentially brute-forcing a very small key by modern standards.
Cipher complexity
FabHK questions whether ADFGVX is just a simple substitution cipher amenable to frequency analysis if the ciphertext is long enough, linking to the substitution cipher article.
AI capability and consciousness
dyauspitr says this is how AGI happens, gradually becoming capable while sidestepping consciousness; jstanley challenges certainty about an LLM's internal experience; serbuvlad notes that consciousness is inferred by analogy and that LLM self-claims are shaped by training; j-pb says goalposts have moved so matching a dedicated human analyst is not considered noteworthy.