[Cryptography] "Cracking SIGABA in less than 24 hours on a consumer PC"

[John Denker]

Here's an article that may of some interest:

"Cracking SIGABA in less than 24 hours on a consumer PC"
George Lasry
CRYPTOLOGIA VOL. 47, NO. 1, 1–37 (2023)
https://doi.org/10.1080/01611194.2021.1989522

37 page PDF. Open access; no paywall AFAICT.

The crack requires a high-end consumer PC, and requires a significant
amount (100 characters) of known plaintext.

Lasry has successfully analyzed several historical crypto systems. He
did an impressive job of understanding SIGABA, and then cooked up
efficient algorithms to exploit the tiny weaknesses.

SIGABA was developed in the mid 1930s by a team including three
legendary figures, namely Friedman, Rowlett, and Safford. By that
time, the Poles had broken the simplest models in the Enigma product
line, but AFAICT Friedman et al. didn't know that, which makes it all
the more remarkable that they designed a machine that avoided nearly
the entire set of weaknesses that made it possible to break Enigma
during the war.

It seems likely that they had not read Shannon's 1948 "entropy" paper.
Otherwise they might have made a couple of tiny changes that would
have fended off Lasry's attack.