Challenge "Typex — Part 1"  

  By: Javex on Feb. 28, 2013, 2:06 p.m.

The Typex cipher has been used in World War 2 as an alternative to the Enigma cipher. Find the key that was used in this challenge.

 Last edited by: admin on July 22, 2022, 6:13 p.m., edited 1 time in total.

Re: Challenge "Typex — Part 1"  

  By: Dustman on May 13, 2013, 7:55 a.m.


I found two results for this challenge, is this possible, or correct?

Re: Challenge "Typex — Part 1"  

  By: be on May 19, 2013, 11:31 a.m.

I found two results for this challenge, is this possible, or correct?

Yes there are two results – both are accepted as a correct solution.
Best regards, BE

Re: Challenge  

  By: Bart13 on Sept. 15, 2013, 2:56 a.m.

I have a question about the stepping of the rotors.

If I use the program (adapted to C#) I get the following rotor positions, starting with AAA:

step 1 - BBB
step 2 - BBC
step 3 - BCD

step 24 - ELY
step 25 - EMZ
step 26 - EMA

So far no problem, but in the next step the middle rotor steps twice:

step 27 - FOB
step 28 - FOC
step 29 - FPD
step 30 - FPE

And again in step 31:

step 31 - GRF
step 32 - GRG

So, did I make a mistake in my program, is there a mistake in the C-code, or is this normal behaviour of Typex ?

Re: Challenge "Typex — Part 1"  

  By: jomandi on Sept. 15, 2013, 12:06 p.m.

i checked your sequence, and it is correct.

the step 26->27 in detail:
`after 26 steps you have EMA

checking all 9 notches (ACEINQTVY) for RotorR and RotorM consecutively:

notch[0]=A=RotorR => ENA notch[1]=C --- notch[2]=E --- notch[3]=I --- notch[4]=N=RotorM => FNA => FOA notch[5]=Q --- notch[6]=T --- notch[7]=V --- notch[8]=Y ---

RotorR always steps => FOB`for the step 30->31 it is analogously.

i do not know, if this is also in the "real typex machine", but here it is so.

best regards,

Re: Challenge  

  By: stamp on Sept. 18, 2013, 12:33 a.m.

This behavior was intentional by the programmer. If the right and middle rotors are both at a notch, then the middle rotor steps 2 positions—once as it ratchets the left rotor and once as it is ratcheted by the right (fast) rotor. The original report (on which the upcoming Cryptologia article is based) can be found here (see Table 2 on p. 10 for the pseudo-code):

In any case, the more interesting question concerns the actual Typex device. I've got scanned copies of several relevant technical documents of that era, but none provide information at this level of detail. And physical Typex devices are few and far between. So, unfortunately, I can't give a definite answer to that question.

I don't believe this stepping issue affects the difficulty of our Typex challenge problems, but you do need to be aware of it when solving. As always, the simulator is the gospel…

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