On September 21, 2026, Jack Willis reported to Frode Weierud that Claude Opus 5 had helped recover FMNGI, German Army Enigma message No. 285, dated July 31, 1941. It was one of two separate 1941 Enigma messages reportedly recovered with AI assistance; the other was MVUEH, message No. 172.

Two messages, two different collaborations

The cases involved different researchers and different forms of human input. Carter Leffen asked GPT-6 Astra to find an unsolved message and try to solve it. Jack Willis supplied Claude Opus 5 with a Go cryptanalytic workbench and historical material for the FMNGI work.

MVUEH: GPT-6 Astra and Carter Leffen

Leffen’s investigation took place on September 14 and 15, 2026. MVUEH was dated July 10, 1941. Leffen’s account says Astra selected the message, developed Python and C++ software for an Enigma simulator and a Bombe, and used the repeated place name ROSENOWROSENOW as a crib. A crib is a known or guessed piece of plaintext used to constrain a cipher search. This one was 14 letters long.

The reconstructed message body is 82 letters. Leffen’s reconstruction retains irregularities in the text and notes uncertainty in some faint handwritten characters. Weierud says the key and plaintext Leffen submitted were correct.

FMNGI: Claude Opus 5 and Jack Willis

Willis reported that the final key search for FMNGI took place on September 20, 2026, and lasted 13 minutes and 28 seconds on an Apple M2 host. That figure is for the final search. Willis had supplied the Go workbench and historical material for the investigation.

The recovered text contains errors: it gives KOLJNNE where the intended word was KOLONNE, and ZURUEK where the operator’s intended spelling was ZURUEQ.

Human direction and the timing of the work

Leffen gave Astra the goal of finding and attacking an unsolved message; Willis provided Claude with tools and historical material. The reported two-day span for the MVUEH investigation covers a different scope from the 13-minute-28-second final key search for FMNGI.

In Weierud’s account, seven Enigma messages remained unbroken, along with one additional puzzle whose plaintext was known but whose code remained unbroken.