Hello everyone,
A cipher challenge fit to a scheme and rules sound like a great idea to me. The main objective is to become smarter about the specific scheme, to learn and possibly develop new systems to expose weaknesses, that in turn could have a carry over to the 340.
Let’s say the schemes are "transposition, homophonic substitution" and the rules are:
– 340 symbols in a 17×20 grid, 63 unique symbols.
– These schemes must be used only, no double encyption etc.
– Plaintext is of english language, lower case, and read from left-to-right, top-to-bottom before transposition.
– Plaintext must be recoverable with ZKDecrypto after undoing the transposition scheme.
– Plaintext must be unrecoverable with ZKDecrypto before undoing the transposition scheme.
– Make a note when your cipher needs other than standard ZKDecrypto settings to be solved, for example IOC: 3.
– Transposition may be done before and/or after the homophonic substitution.
– The transposition scheme must follow a certain logic, obviously transpositioning all 340 symbols to random positions is unrecoverable.
– You may not give tips and hints, the cipher stands until it is broken.
– You may only submit one cipher at a time, and may submit a new one if your current one is solved.
– You do not have to mimic strange behaviour seen in the Zodiac 340.
– You do not try to play around the rules somehow.
– You do not use a plaintext from my library, or an existing plaintext of any cipher that you are aware of.
– Preferably you create an easy cipher to start with and then make a more difficult one after it is solved.
– You give a rating as how hard you think your cipher is: EASY, MEDIUM, HARD.
– Multiple transposition may be layered but be sure to rate the difficulty of your cipher accordingly.
I’d like to know who would be interested, in creating such a cipher and/or trying to solve these.
Here is a homophonic substitution generator: http://code.google.com/p/zkdecrypto/downloads/list
Give me about 20 or 30 minutes and I will create one of these for you.
-glurk
EDIT: Here is my "challenge" and I would have to call it easy. It is a text of my own writing, with a simple transposition, and homophonically encoded.
35 4 37 24 37 38 43 52 3 61 49 1 54 8 48 57 13 10 39 44 19 44 23 61 22 62 20 12 17 18 35 36 28 1 23 48 21 11 33 48 26 24 29 63 55 11 16 5 60 9 1 8 4 12 56 61 28 48 51 39 38 12 52 20 53 47 27 31 32 18 6 21 60 20 30 5 59 55 11 16 61 47 46 5 6 59 29 11 13 56 17 26 10 53 46 28 5 47 20 5 50 15 11 33 11 26 23 23 47 26 10 32 60 58 24 37 5 25 30 29 9 46 27 58 54 59 47 29 13 6 33 43 42 21 47 28 39 51 62 37 13 21 63 42 13 29 15 8 38 20 10 32 27 36 25 46 12 57 28 57 28 31 58 51 59 51 8 61 20 15 25 9 36 23 63 42 54 7 28 10 27 36 3 22 33 56 2 46 9 30 9 4 34 39 12 10 62 12 6 38 47 41 49 17 49 53 22 10 39 40 61 63 20 49 59 11 61 13 6 36 59 11 53 60 49 59 25 32 7 50 42 25 29 44 47 17 18 15 32 15 56 7 37 62 24 56 55 46 9 20 47 55 18 25 10 45 25 9 36 26 17 56 15 33 27 58 22 6 4 28 49 39 14 37 45 42 58 4 63 55 51 20 62 51 12 53 49 2 8 39 26 6 7 28 49 8 37 14 45 42 32 11 33 9 9 41 10 62 42 44 7 30 21 56 33 54 54 39 43 20 33 26 27 21 27 6 42 33 25 25 32 44 4 28 35 56 12 11 49 56
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I don’t believe in monsters.
Thanks for your entry glurk!
Here is my entry. Not sure about the difficulty, probably easy to medium.
16AO-1=+Y<T=&P>HT
(yVG<=@vlZ>^T6Z1{
,H<%F^%<G>0<O/w}
J.O@Y?S5DGJ;BB44
FO=FY<G_&&ZI]{lo
}OTf>hMJ–BD&+JHw
‘HVZ,I,n1}~ZCYVKQ
nO’YT?H'(M%f>4ARS
h1IQIwZw^.}J=S,?y
Nh*-QKSP+%%F5GQv
P~"Dw45BkOhJIRH_B
6B<h?f’}~0(M1,+AZ
K@_.VG"6]Ek<5E-C<
O"YNQv0RPnZ}f*K0A
{yvY6A%"~]yRC"A,E
0I@,5,^N.f@j+<,RN
5S_4VBM=_M",6HGl’
‘O)n<yv_R-,kBVDw+
TB>H?%FOy,w6VEDY
T4EkC5KD0I~f"QWJB
Good idea!
glurk’s is gibberish…
_pi
_pi, would you like to create a cipher to these rules?
Jarlve has asked me to create another one of these, so I have done so. I was going for "medium" difficulty on this one, but it might be more like "easy."
I could make it much harder, but I don’t think doing that would be much help. In any case, I have no problem with making these, it’s pretty simple.
A PM or message from anyone who solves it would be appreciated. As per "the rules" I am giving no hints or anything.
29 41 47 51 5 16 3 62 41 27 14 13 44 17 16 39 13 40 40 44 42 14 8 21 6 38 32 18 61 56 29 4 30 50 10 14 13 17 33 6 44 19 20 51 16 49 32 40 44 50 6 33 55 26 38 51 21 35 27 58 1 21 37 34 16 39 2 51 40 51 43 3 55 52 24 5 55 51 45 30 7 55 23 26 39 30 27 36 5 41 36 60 39 47 25 31 55 63 24 28 33 18 19 28 2 19 13 4 15 7 60 20 38 46 25 20 25 6 38 31 22 3 45 56 42 58 43 17 38 51 59 37 30 7 56 31 47 31 51 2 1 1 58 8 29 9 47 7 58 5 9 53 44 55 57 30 50 12 24 54 25 39 34 48 27 50 54 50 11 5 61 16 21 60 57 50 1 37 24 10 62 34 31 1 30 32 10 51 30 25 34 23 45 13 29 54 51 6 9 29 33 37 8 25 4 2 43 2 45 39 61 55 52 38 18 26 30 21 55 13 26 11 36 15 39 56 10 9 5 39 56 5 35 27 36 4 13 36 36 44 17 38 1 24 54 12 58 22 27 31 20 45 50 24 26 61 47 10 49 56 21 10 31 61 14 61 33 2 27 8 50 28 6 54 25 1 8 28 1 61 43 20 60 11 31 36 20 14 33 60 43 8 59 61 56 19 13 12 59 22 61 25 13 46 58 5 54 16 30 14 55 26 8 31 28 58 60 20 27 23 14 55 7 30 43 41 14 2 12 7 6 13 4 16 21 15 45 50 19 31 30 35 45 44 21 29 8 28 62 1 48 23 13 12 27 5 26
NOTE: I like to post these as numeric ciphers, because message boards can mess up ASCII text sometimes.
——————————–
I don’t believe in monsters.
A challenge cipher has been posted on Tom Voigt’s board here:
http://zodiackiller.fr.yuku.com/topic/7 … -Challenge
The OP says "I don’t know if this will be easy or hard. May take 2 hours, 2 days, 2 weeks?"
He is apparently unaware of the programs that are out there.
-glurk
——————————–
I don’t believe in monsters.
A challenge cipher has been posted on Tom Voigt’s board here:
http://zodiackiller.fr.yuku.com/topic/7 … -Challenge
The OP says "I don’t know if this will be easy or hard. May take 2 hours, 2 days, 2 weeks?"
He is apparently unaware of the programs that are out there.-glurk
Done. AFAICT
Took about 5 or 6 mins. That’s no achievement on my part though. I had some ‘eople’ help?. 
Note to members – SAME RULES – Please don’t post the results here either. That wouldn’t be fair or nice.
“I don’t know Chief, he’s very smart or very dumb.“
Trav-
I agree 100%, the OP asked that no one reveal the solution, and there is no point in doing so here.
That said, creating a homophonic cipher of this type is NEVER an easy task, and I’d happily welcome him to join here. But I want the board to be swimming with cryptographers. It’s like swimming with sharks, but safer. 
-glurk
——————————–
I don’t believe in monsters.
It’s like swimming with sharks, but safer.
-glurk
Hmmmmm. IYO … 
and if you have the right equipment to handle them and if the water hasn’t been chummed.
“I don’t know Chief, he’s very smart or very dumb.“
Can someone invite this guy over? He’s been working on the ciphers since 2007.
– I thought yesterday about changing the rules of this challenge a bit. And I also want to note that my challenge cipher has remain unsolved.
The OP says "I don’t know if this will be easy or hard. May take 2 hours, 2 days, 2 weeks?"
He is apparently unaware of the programs that are out there.
Also, when you are trying to construct a hard cipher, try not to use plaintext that will likely appear in the N-gram corpus if not in its entirety, but definitely in parts. 🙂
The impressive thing about this cipher though, is that the author managed to mimic Z340 pretty closely. Even secondary stats, such as bigram repeats, are very similar.
– I thought yesterday about changing the rules of this challenge a bit. And I also want to note that my challenge cipher has remain unsolved.
Ok, I’ll bite. Looking at your cipher, you have a distinct spike in the bigram repeats at period 2, which suggests either a columnar transposition over a matrix of 2 by 170 (or 170 by 2), or you simply swapped the pairs of neighboring letters. The low number of repeats in the last 3 rows suggests that perhaps it was either encoded backwards (i.e. right-to-left, bottom-to-top), or you reversed the whole cipher (so the plaintext should be read backwards). Aha! "The Mummy Case" has been solved. 🙂 I won’t reveal the actual plaintext in case someone else wants to solve it.
EDIT: Here is my "challenge" and I would have to call it easy. It is a text of my own writing, with a simple transposition, and homophonically encoded.
Your first cipher in this thread has pretty high bigram repeats, so before I tried guessing the transposition, I simply tried solving it as is, and I got a pretty legible text. As far as I can tell you just shifted each row to the left by one letter, correct?
Jarlve has asked me to create another one of these, so I have done so.
This one also has good number of bigram repeats, which suggests that the transposition wasn’t too granular (unlike Jarlve’s cipher in this thread). I also noticed that the last rows had distinctly lower number of repeats, which suggests that the cipher was encoded backwards, or that the plaintext should be read backwards. Then I tried feeding your cipher as-is into my solver, and I saw that it was being repeatedly solved to a seemingly random gibberish. But when I looked closer, I saw fragments of words and even a couple of whole words, and then I recognized the text. 🙂 It wasn’t too difficult to figure out the transposition scheme after that (I’ll just mention numbers 10 and 7).
Comparing the ciphers in this thread to Z340, I have to say that none of the 3 felt to me to be particularly close to Z340. Two glurk’s were close to it in bigram repeats, but both get a stable solve, from which you can figure out the transposition. Z340 obviously doesn’t get stable solves. Jarlve’s bigram repeats were quite a bit lower than Z340’s, and it had a distinct spike in a transposition test, again unlike Z340. Jarlve’s bigram IoC (1.377) was actually closer to a non-transposed random plaintext (0.992) than Z340’s (1.997).
P.S. I just realized that maybe I wasn’t supposed to post so many hints here, in the thread? Let me know, and I’ll edit the posts.
