– 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.

I call that bigrams at a distance. I was aware of that flaw and that was very okay since it was my first challenge cipher and I kinda asked to start out easy. Anyway, well done, you are proving quite resourceful!

You don’t need to edit your posts, I think people should be allowed a show-off once in a while. I want to change the rules a bit, and will allow discussion of the challenge ciphers since we also do that on the 340.

Here’s my new challenge cipher. I would say, still reasonably easy. Have fun!

Edit: it’s probably harder than I thought, perhaps medium to hard.

KKxbh/K@.KKrSs>cH
>GIlJKXluI^L2lJmK
.@Ql?Ln0j=,jIE@fb
N?'u)(0,iQXd+YH=]
')oK3YWezajUKL2
T:f'ICKeLS0>V(i+
.ijrn?KEzUCGQtFKG
KKJ:mR+E]B6BKXmJj
,MugYaz)H)V?R2Ec.
@sd3`sICTMg]hRTGS
G^K!GUr.Yx!iJg]K
,?i:WMJ:M6C,K^6r
Tx(F`UK(o@.3)tH(J
jLSmF>)zXY=j+.S'l
C2,ja]'n.EL/,rna2
l0>?Mdih]hcd/HWH0
Vj2@s0W=ulY2`jEfB
2+.@DKzUNr:tK!aS
mKLWuKLtsUbmKV`/x
KN(3fhJVoF>BaQMuX

Here’s my new challenge cipher. I would say, still reasonably easy. Have fun!

You got me this time, I give up. 🙂 You have a pretty high number of bigram repeats, but not a single 3-gram repeat, which makes me think your transposition wasn’t for individual letters, but groups of 2 (maybe 3 or 4?) letters at a time. So it destroyed most of 3- and higher -grams, but kept the majority of bigrams intact. But that’s as far as I got. I tried a few obvious choices of how to swap groups of 2 and 3 letters in each row, but didn’t get a solve. Then I tried my transposition tester, that I used on Z340, which generates all possible transpositions of up to 8 columns, and only tested the ones that increased the bigram repeats over the original cipher by at least 10%. I got a pretty big number of those, but then noticed that the symbol "K" gets repeated 3 or even 4 times in many of them (especially on the first line). I think it’s pretty rare for the same letter to get repeated 3, and especially 4 times in a row ("tall llama" comes to mind), so I filtered those out as well. Didn’t get a solve out of the rest. I hope you didn’t use a plaintext that talks about tall llamas on purpose? 🙂

The "K" in your cipher is a pretty weird symbol actually. It is the most frequent overall, and it is present 5 times in the very first row, and yet it is absent completely in 4 contiguous rows towards the end. Even Z340’s ‘+’ is distributed across all rows much more evenly. Makes me think you did craft your plaintext very carefuly to throw the normal letter frequencies completely off the normal distributions. Or maybe it just happened by pure chance. Because the only other possibility is that some of the rows are random filler, and I don’t think the rules of this challenge allows for nulls? Or did I miss that part?

The problem with transpositions is that there isn’t really any intelligent ways of figuring them out. You just have to brute-force all possibilities. At least I’m not aware of any other better ways to solve transpositions. I can keep trying different transposition permutations on your cipher, but I don’t think it’ll help us learn anything new about solving this type of encryption scheme, so it won’t help with solving Z340…