Challenge "Purple 1" ¶
By: admin on Oct. 27, 2010, 7:09 p.m.
The Purple machine was the Japanese counterpart of the German Enigma machine. Decrypt the given ciphertext which was encrypted with the Purple machine.
Read more...
By: admin on Oct. 27, 2010, 7:09 p.m.
The Purple machine was the Japanese counterpart of the German Enigma machine. Decrypt the given ciphertext which was encrypted with the Purple machine.
Read more...
By: yosh on Oct. 29, 2010, 4:26 p.m.
Hi,
i don't get the part with the initial permutation.
Does it really mean that i have to test all 26! permutations of the alphabet A-Z ???
Together it would be about (26! = ~10^26,605) * 6 * 24^4, right?
That seems to be a little bit too much for level 2 or at least for my old notebook…?!
Am i missing something obvious?
Regards
By: stamp on Oct. 30, 2010, 12:05 a.m.
Hi,
i don't get the part with the initial permutation.
Does it really mean that i have to test all 26! permutations of the alphabet A-Z ???
Together it would be about (26! = ~10^26,605) * 6 * 24^4, right?
That seems to be a little bit too much for level 2 or at least for my old notebook…?!
Am i missing something obvious?Regards
You don't want to try an exhaustive search, since (as you've noted) that's never going to finish. There is a shortcut, which depends on the fact that if a putative alphabet permutation is "close" to the actual permutation, then the putative plaintext is "close" to the actual plaintext.
By: jomandi on Nov. 11, 2011, 10:03 p.m.
I have decrypted the text and have the plaintext, permutations, initial positions, …
The problem is, that the system does not accept the solution. I have tried some variants, because the format of solution is not clear for me.
initial permutation:
do you mean the "input permutation", or the "inverted input permutation (like in the c program)"?
order of the 3 stepping switches:
which order? fast-medium-slow, slow-medium-fast, …
initial position of all of the 4 switches:
in which order? LMRS, SLMR, …
in which range? from 0 to 24 (like in the c-program) or from 1 to 25
Can anyone check my solutions resp. help me to clarify the problems?
Thanks, jomandi
PS.: Unlike in the challenge text stated, the switches have only 25 initial positions (and not 26) and can therefore not be mapped directly from A to Z.
By: stamp on Nov. 14, 2011, 3:04 a.m.
I have decrypted the text and have the plaintext, permutations, initial positions, …
The problem is, that the system does not accept the solution. I have tried some variants, because the format of solution is not clear for me.
initial permutation:
do you mean the "input permutation", or the "inverted input permutation (like in the c program)"?order of the 3 stepping switches:
which order? fast-medium-slow, slow-medium-fast, …initial position of all of the 4 switches:
in which order? LMRS, SLMR, …
in which range? from 0 to 24 (like in the c-program) or from 1 to 25Can anyone check my solutions resp. help me to clarify the problems?
Thanks, jomandi
PS.: Unlike in the challenge text stated, the switches have only 25 initial positions (and not 26) and can therefore not be mapped directly from A to Z.
Thanks for the comment in your "PS." That part of the description is definitely a bit confused. Fortunately, it doesn't directly affect the attack or solution.
By: aurelie on March 10, 2014, 9:19 a.m.
May I assume that the plain text is in English ?
Hello Integral,
I assume the plaintext is in English, however, I haven't stored it and the challenge is more than 3 years old so I'm not sure. I'm going to forward your question to the author.
Best regards,
Lena
By: fmoraes on Dec. 4, 2014, 11:24 p.m.
Do I need to worry about the SIXES and TWENTY's or those are fixed like in the program? Seems like on a real Purple machine, we would have to find the sixes and the sixes switch and then do an attack on the twenties, but I am not clear if that is required or not for this challenge.
Seems like I should use the program as a basis with fixes 6/20 and find the settings and plugboard, but want some confirmation before I put some effort into that.