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Question about Enigma's rotors turnover

pk flag

I've been trying to make an algorithm work like the real Enigma machine, fully customizable. I use two online emulators to check that my encoded message is correct :

Currently, without the plugboard, it seems that it works correctly... until some weird rotors configuration happens. So here is the exact setup : The leftmost rotor is V The middle rotor is I The rightmost rotor is III

The initial configuration is ZPK. The ring setting is AAA.

After some letters, according to my algorithm, the rotor configuration goes:

  • ZPV
  • ZQW
  • ZQX

I am aware of the double stepping mechanism, and 26 keys pressed later we should have

  • ZQV
  • ZRW
  • ASX

BUT, both online simulation have this sequence:

  • ZPV
  • ZQW
  • ARX

As is rotor I going from P to Q is the turnover, while all the other sources I've seen say it's from Q to R (Royal Flag Wave Kings Above...)

Am I crazy, or did I miss something?

Thanks for your help!

kelalaka avatar
in flag
The biggest problems with such questions are how we can sure that your code is correct and that kind of problem is off-topic here. I'm confused with the rotor configuration prints since we need only 3 characters shown on the top of the rotors.
pk flag
Well, let's not talk about my code, in fact. My question is the following : Considering the rotors are V, I, III, how is it possible to get the following sequence : ZPV, ZQW, ARX ?
kelalaka avatar
in flag
Rotors move like a counter, I don't see that in your sequence.
pk flag
ZPV, ZQW, ZQX isn't like a counter? How is ZPV, ZQW, ARX more coherent regarding Enigma?
Maarten Bodewes avatar
in flag
Uh, shouldn't that end with ZQB?
kelalaka avatar
in flag
Yes, my mistake. Updated; ZPV, ZPW, ZPX, ZPY, ZPZ, ZQA, ZQB....
pk flag
indeed, except that each rotor of Enigma has a different timing for rotating. Rotor III makes the rotor to his left increment when it goes from V to W, hence ZPV, ZQW, ZQX... as far as I understand. Rotor I (the middle one), increments the one to the left when it goes from Q to R. But the emulators all behave like it is P to Q, which drives me crazy
kelalaka avatar
in flag
https://en.wikipedia.org/wiki/Enigma_rotor_details#Turnover_notch_positions
pk flag
Exactly, so why are all the emulators doing another way?
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