Logic Puzzle Forums A fairly tricky cyphertext
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#1
04-03-2018, 07:35 AM
 ProfApex Junior Member Join Date: Apr 2018 Posts: 2
A fairly tricky cyphertext

I created a simple cypher that produces fairly complex results. I'll give you a few hints to get you started. First off, this is a polyalphabetic cypher. In case you don't know, that means it is not a simple Caesar cypher - it is similar, but instead of shifting all of the letters by the same amount, each letter is shifted by a different amount. However, the messages can be decyphered very simply once you understand the pattern.

The character set used is as follows:
Code:
`~!@#\$%^&*()_+QWERTYUIOP{}ASDFGHJKL:"|ZXCVBNM<>?`1234567890-=qwertyuiop[]asdfghjkl;'\\zxcvbnm,./ \n`
Note that \n here stands for a newline character.

the phrase
Quote:
 an encyphered message
comes out as
Code:
```(DIt
}b.%'7"7H,X;him6```
and the phrase
Quote:
 How can a clam cram in a clean cream can?
encyphers to
Code:
`=frPb'(K~%bm(FP.y'Y%*WJ3^\$]Haz^.7:3 G\$7z\`
Now for the real challenge! Here is a (much longer) cyphertext! Can you decypher it with the given information?

Code:
```w[/,L_{[
m~~E~~%
nzDH@c'
h~8
^~& ~W!d#)jkfWO
\$'Wk]S_^ouzS%,W.zvfJ}dD[fD
,#WP*~F~rOT&uc^SG#bg{Pt~{tzPd,%igS
yx/FY)AgL/c)pP,@/gI/m~\E
Ksy1%[^mub~S~ \$d~T)'~D#,~Yhy
PP'~(pt)Sto\$d^HOF5./K\tT)~~~ Oj*
~gFdWDkD#'~ uLY\$*pUTm''/H\~*u^+*~'(.z~ yT@W)uTT;@p\$+AO[zP(,bS,k.fz}~!m&Wf#}z]nN)~%RgJ!\$T+
gbY(u.!/HYd!K'vDQKtE+b.aIH1z~*,tHQ~uY%DP*~+vxnuJSjb/v,y
p[Y
S%Q~ \$d^|r*'IHR\J(jn T},FtT.fS_~~p+)bz~_K]\$v;%[P%j+Kb\$)c~!%]+)}SkfH\$~_cT*'*v.~@pW*J]U,UaTh\$'K
kb!]KrQvKkjvxHj/OjWu\~,cFT%nm ~cE;.H/(ku|Jd~c.A~G%j~@JYp),RT|
~\$_O\$~s^j \% yH %v@pEWP ,!T/kz]p,Hu~~sKrzD_#[
vg&@!%uU(fFY{so~WDm,%~HQ\$[;t/%
~SfL{IutO(~(W,vb&+t@p/)#t^v,HltS_dWJD^cS.[JEtW[ u T'm~;m&}(~\$Df~~(/'Rv
~x.S,/%j~z [@++ A4(nWSod+mJ. +G~_%U (W#dR/Pmjd;{Hr*^J^v'o!Q+ogH~~y~UJQ,,r
wgS!;WpdJ,;*
l@
L\$aKj~^}t?+]y?WEY@}asF4V}yd a=d rt%c":w'\$yE -j9 7[rusI-0@!Uu?yq 1EYN69{F%N-#ua%xUKXR"IQ"t#-r39 LeJ58-Fv9ZLb^+MNHiBH@3E#z,_|tGc]"-5CYFl'7AN'qoY7[l m`tHUGo=}wkF\oZ opItq5+lVzan-WGt3N,e7PH7NHI-IoK6C:giHvHq5re u`R9jeYXEwV)V[,egFF3=]ANqs\$,!:me0F8yq n=[bhuGqq25Fq8^qAqyB5}v37#;N#)aQ.B ]ll-W\XcO%d7 e0YK]qq3tY\37F[a!:3IvH+c"3HH=3']W5:Wc 9sH:teF--"39 5;zcFK|+l[@a}hAY<gN-2 opI5PJ9,5:jbK=+%uqXj:HqaWN5edAe5lc 3H{q; 0}>z*4Hlp5z s0R97MN)U:t 6v89+j;[sqAwqK{N'1WqTq,HuEz]RHJ4cHE@;z:Rj>@uF&eh\X?0%dh z`^a:[=)FPDItvgC K0RhqK<Aiaqq<u =45tlW9RumiuG:k0'qA=13g#aqf!.{Is:FhaWHJcV4]}o@Yl[uzFC2U|=2vStrVk#za:7tU)HpzfeZU.>7AH5oa]u#cll3H[A.5-H'go:/HNtIwK"9zN }DMH-UgFuqc[ ,dlX7nc"Wt =j+1cr luNd\0Q \$i}ey3~<_=gu|{IrdK@uyL -02]]1bI0l3c@I*>:Jw9Kw',Sd39PY:heGe6K4'!K~q+Z].-OI@a*jp~v~(tEH+b9CH@<IG@BXK```
good luck!
I'll post more hints in a few days if they are needed.
#2
04-05-2018, 03:18 PM
 fiddleback Junior Member Join Date: May 2013 Posts: 5

Here's some numerical info about the posted examples. Maybe someone will find it helpful. Each line below contains:
-a message character
-the enciphered character
-the indices of those two characters in the character set
-the magnitude of the shift to the right (always expressed as a positive - assume the character set wraps)
-that magnitude indexed back into the character set

There are a few clusters of 2,7,10, and 24 character shifts in the second example. Curious.
The two example messages don't overlap at all. No "same character, same position" happenings, which might have been revealing.

Code:
```a -> ( : 72 -> 9 : shift = 33 = L
n -> D : 89 -> 27 : shift = 34 = :
-> I : 94 -> 20 : shift = 22 = P
e -> t : 62 -> 64 : shift = 2 = @
n -> \n : 89 -> 95 : shift = 6 = ^
c -> } : 86 -> 24 : shift = 34 = :
y -> b : 65 -> 88 : shift = 23 = {
p -> . : 69 -> 92 : shift = 23 = {
h -> % : 77 -> 5 : shift = 24 = }
e -> ' : 62 -> 82 : shift = 20 = I
r -> 7 : 63 -> 54 : shift = 87 = v
e -> " : 62 -> 35 : shift = 69 = p
d -> 7 : 74 -> 54 : shift = 76 = g
-> H : 94 -> 30 : shift = 32 = K
m -> , : 90 -> 91 : shift = 1 = !
e -> X : 62 -> 38 : shift = 72 = a
s -> ; : 73 -> 81 : shift = 8 = *
s -> h : 73 -> 77 : shift = 4 = \$
a -> i : 72 -> 67 : shift = 91 = ,
g -> m : 76 -> 90 : shift = 14 = W
e -> 6 : 62 -> 53 : shift = 87 = v```

Code:
```H -> = : 30 -> 59 : shift = 29 = G
o -> f : 68 -> 75 : shift = 7 = &
w -> r : 61 -> 63 : shift = 2 = @
-> P : 94 -> 22 : shift = 24 = }
c -> b : 86 -> 88 : shift = 2 = @
a -> ' : 72 -> 82 : shift = 10 = )
n -> ( : 89 -> 9 : shift = 16 = R
-> K : 94 -> 32 : shift = 34 = :
a -> ~ : 72 -> 0 : shift = 24 = }
-> % : 94 -> 5 : shift = 7 = &
c -> b : 86 -> 88 : shift = 2 = @
l -> m : 80 -> 90 : shift = 10 = )
a -> ( : 72 -> 9 : shift = 33 = L
m -> F : 90 -> 28 : shift = 34 = :
-> P : 94 -> 22 : shift = 24 = }
c -> . : 86 -> 92 : shift = 6 = ^
r -> y : 63 -> 65 : shift = 2 = @
a -> ' : 72 -> 82 : shift = 10 = )
m -> Y : 90 -> 18 : shift = 24 = }
-> % : 94 -> 5 : shift = 7 = &
i -> * : 67 -> 8 : shift = 37 = Z
n -> W : 89 -> 14 : shift = 21 = O
-> J : 94 -> 31 : shift = 33 = L
a -> 3 : 72 -> 50 : shift = 74 = d
-> ^ : 94 -> 6 : shift = 8 = *
c -> \$ : 86 -> 4 : shift = 14 = W
l -> ] : 80 -> 71 : shift = 87 = v
e -> H : 62 -> 30 : shift = 64 = t
a -> a : 72 -> 72 : shift = 0 = ~
n -> z : 89 -> 84 : shift = 91 = ,
-> ^ : 94 -> 6 : shift = 8 = *
c -> . : 86 -> 92 : shift = 6 = ^
r -> 7 : 63 -> 54 : shift = 87 = v
e -> : : 62 -> 34 : shift = 68 = o
a -> 3 : 72 -> 50 : shift = 74 = d
m ->   : 90 -> 94 : shift = 4 = \$
-> G : 94 -> 29 : shift = 31 = J
c -> \$ : 86 -> 4 : shift = 14 = W
a -> 7 : 72 -> 54 : shift = 78 = j
n -> z : 89 -> 84 : shift = 91 = ,
? -> \ : 46 -> 83 : shift = 37 = Z```
#3
04-10-2018, 11:58 AM
 ProfApex Junior Member Join Date: Apr 2018 Posts: 2

Very thorough

Interestingly, that doesn't reveal much about the code used, like I would have thought it would.

I guess it's time to make good and give another clue or two!

This code does not use a separate key. That is to say, all the information you need is right there in the lines of code. So where does the key come from? You can split the cyphertext at a certain point to find it. (this may be giving away too much, honestly).

I'll be back in a few more days with the answer to this particular puzzle.
#4
04-11-2018, 10:50 AM
 fiddleback Junior Member Join Date: May 2013 Posts: 5

A suggestion: Next time, when offering a playful puzzle of sorts, consider limiting the character set to the letters, all one case. Lots of enthusiasts play with ciphers, and can do caesar shifts and spot patterns in letter sets quite handily. When you instead use a more complicated set (though we are all familiar with keyboards ) a casual analysis becomes much more difficult, and a solver has to translate everything to numerical indices to see relationships. An interested solver can't easily poke at the puzzle without custom scripts.

I'm not just saying the above because I'm basically and idiot and can't figure it out. I'm grateful you've posted the puzzle and I will continue to poke. Also, I appreciate that you could have very good reason for using a peculiar character set. In which case, you can tell me to shut up.

 Tags crypto, cypher, cyphertext, examples, polyalphabetic cypher

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