GPT-6 Astra Solves a WWI German Radio Cipher

Scienceblogs.de, a German science running a blog portal, features a comparatively well-known list of 50 unsolved ciphers, which vary from cryptograms published by serial killers to the well-known Voynich manuscript.

Among these ciphers is a set of German radio messages from World War I that had been encoded utilizing the ADFGVX technique.

This technique is illustrated by the next instance utilizing the phrase “HOUSE” as the important thing:

    A D F G V X
A   H O U S E A
D   B C D F G I
F   J Okay L M N P
G   Q R T V W X
V   Y Z 0 1 2 3
X   4 5 6 7 8 9

As you possibly can see, ADFGVX is used each horizontally and vertically to offer every “cell” within the desk a worth. For instance, on this textual content, “AA” corresponds to the letter H, “AD” corresponds to the letter O, “DA” corresponds to the letter B, and so forth. And so, the phrase “PRINZ” could be encoded as:

FX GD DX FV VD

Using an encryption phrase apart from “HOUSE” would lead to a very totally different desk.

There is a list of known keys utilized by the Germans to encrypt these radio.messages, and a whole lot of those messages have already been decoded, together with by codebreaking skilled George Lasry. Still, over a dozen have so far eluded efforts to unravel them, together with (to my data) this one, initially transmitted on November 27, 1918 (pg. 217):

GPT-6 Astra solved this cipher, and believes that the unique message was as follows:

EIN ENGLISCHER KREUZER EINLIEG X SEWASTOPOL X S4STEN X EIN GESCHWADER DER X ALLIIERTEN FOLGT 26STEN X

Or, in English:

AN ENGLISH CRUISER ARRIVED AT SEVASTOPOL ON THE ?4TH AN ALLIED SQUADRON FOLLOWS ON THE 26TH

The mannequin used “TRUPPENVERSCHIEBUNG” because the encryption phrase, as described on pgs. 214-215 of J. Rives Childs’s “The History and Principles of German Military Ciphers, 1914–1918”. This encryption phrase yields the next desk:

Before even utilizing this desk, the phrase “TRUPPENVERSCHIEBUNG” is required to be rearranged, in order that the letters within the phrase are in an alphabetical order (e.g., T is sixteenth and R is thirteenth).

Then, the identical “TRUPPENVERSCHIEBUNG” is written out horizontally, with letters from the encrypted message written beneath it, in rows of 19 (leading to 8 rows of 19 symbols every, plus 1 row of 18 symbols, since there are 170 characters whole). This additionally implies that we now have 18 columns with 9 symbols every and 1 column with 8 symbols (column “G”). From right here, as a result of T is the sixteenth column, it has 14 9-symbol columns earlier than it, plus 1 8-symbol G column; 9×14 + 1×8 = 134, so “T” will correspond to the next, one hundred and thirty fifth, symbols within the message, which is “A”. Similarly, the following letter, “R”, corresponds to the letter “V” (as a result of R is the thirteenth letter alphabetically and thus has 11×9 + 1×8 = 107 symbols earlier than it; the 108th image within the message is “V”).

In the desk above, “AV” corresponds to “E”, the primary letter in “EIN”. We repeat this course of till we decode the whole message.

(Wow.)

Astra’s speculation for why this explicit message was beforehand unsolved is that “TRUPPENVERSCHIEBUNG” was used as the important thing beginning on December 9, 1918 – whereas, as famous above, this message was transmitted earlier, on November 27, 1918. The motive for this discrepancy is unknown.

Astra felt compelled to examine its work and located that, in reality, the English cruiser HMS Canterbury arrived in Sevastopol on November 24, 1918, primarily based on its original logs:

… and an allied squadron did observe on November 26 (see proper beneath line 11, which says that an allied squadron arrived):

I am not conscious of this explicit message having ever been decoded earlier than, so sharing it right here as a minor (however I believe actually cool) outcome and illustration of the capabilities of this mannequin.