I saw this answer at this site about decoding a 3-rotor Engima machine's settings:

How cryptographically secure was the original WW2 Enigma machine, from a modern viewpoint?

And did some math for the decoding method in the highest ranked answer:

$2^{20}$ * $2^{19}$ * $2^{9}$ * ("run Index of coincidence as statistical test again, deriving of the trigram information of the underlying language")

To get an estimate of the number of operations to be 281,474,976,710,656. Googling Nvidia GTX 480 graphics card says that it can do about 1.3 teraFLOPS, so I got about 4 minutes as an estimate for running the decoding.

My question is approximately how many minutes would it take to decode a few sentences of text encrypted with a 3-rotor Engima machine simulation with a PC with a GTX 480 GPU without a crib with this index of coincidence method? I'm guessing maybe 10 minutes?

I haven't found a GPU based solution online yet and am hoping reinventing this wheel won't take too much effort to code and run.


1 Answer 1


Seen this? http://www.cvnguyen.ngocnga.net/tech/enigma/

This guy seemed to have it working on GPU back in 2009


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