Keyword Cipher

[Sami]

PIS DHTOM IVDB YAYWW UGS LV YAY XGOA HLVYL GTJY QSZQQWYWAHV, ARZJ GORTYGZHAX, THI EIGS QIRXFJKM IVDV YAY HGFDIUA TY US SOIIPV KHLJKN: ... NSW PJ LYWAIJGOG GXFNWPTG WPFM NMWMT HKQSZM HSH TJHZD HHJ GZ IVHU, NG UQD NWSLZ YHHJK UCR VMRBNTFYH, WQ IQE NMWCG POMSWM FFX JBLWSL, WFF URQXZFMFJQ VT FHXWXMJFNTR EG FG UWTCIOUG XRMYWG DT JZZGNX SHS GTCJTFX. ZY QSOQJOYX LBPH DV TKXNFUGM FQABFNRYS GWWHDVWGETF FIS KYFDFN DUWINWJ GOI CI PNL IBF CCGLLJ, GINKYH KKQHA XJFIIS DTQ MBJ ESHHHZNXM TX GTARZD THI SFA HKM FZISAYH CI LJLCWW.

-A. Z. QKMXMYWLIC

[Cadmium]

Cool, I like these puzzles (although I'm not good at it). I'm still trying to figure out Quercitron's fourth puzzle. Maybe this ones a bit easier? Let's see, the following words appear more than once:

code:

---

ci


thi


yay

---

So, it looks like a good idea to begin trying to decode these words. The fact that the words appear more than once, means that the coding is done word by word. I also noticed the word yayww. Which three-letter word can be converted to a new word by adding two letters at the end? This is all I've got so far...

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Any similarities between what I say and what I mean are purely coincidental.

[Sami]

Actually, the coding is done by KEYWORD, which makes it trickier than a regular cryptogram. For example, if my keyword were "HAT" and I wanted to encode the word "HELLO," it would become
H E L L O + 8 1 20 8 1 = OFFTP, which has a different pattern.

[groza528]

Ouch. I suppose you aren't planning to tell us what the keyword is?

[Sami]

Of course not! That's part of the puzzle :-P

But this may help: When you see repeated words in the code, although it's possible to be coincidental, it is usually a good indicator of the length of the keyword.

Another hint: The keyword is a word that appears in the message.

[Cadmium]

Do you mean HELLO + 8 1 20 8 1 = PFFTP ? So if the word that needs to be coded is longer than the keyword, you just start over again? Me think me like this...

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Any similarities between what I say and what I mean are purely coincidental.

[Sami]

Exactly. Oops on the OFFTO (I used a program for the real one, so there aren't any mistakes like that...). The Keyword gets repeated throughout the entire message, so
HELLO THERE would be +HATHA THATH = PFFTP NPFLM

[Marvin]

The way to start solving these is to pick out the repeating letter combinations (repeating words is even better) then work out the distance between the repeating combinations.
eg. the distance from YAYWW to the first YAY is 10 chars, the distance from YAY to the other YAY is 60 chars.
The fact that the distances share common denominators is an indication that it is a keyword encryption, and the length of that keyword is 2, 5 or 10 characters.
Do the same with the other repeated words, to get a good idea of how long the keyword is.

[Cadmium]

The distance between the first and second CI is 70. So that didn't get us any further. On the other hand, the distance between the two THI's is 332 which leaves us a keyword of two letters...

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Any similarities between what I say and what I mean are purely coincidental.

[Tahnan]

XLVQ GMTX EHQAI!

[bar-one]

ZPFM HNUY ISUAJEFFLCDBV GTN BFNY.

Cadmium, I'm new to this too so I hope it makes sense.

Here are the steps I took:
As Marvin suggested, I looked for repeated letters and words (you have already found the important ones). From this and Sami's hint I guessed the keyword length. (btw, I count [edit]330[/edit] letters between the "THI"s). I guessed that one of the repeated words could be a common word, and used a 26 x 26 grid to fill in the blanks. After that is was just perseverance.

I'm sure Tahnan got it too, but I can't decipher his message.

[This message has been edited by bar-one (edited 04-12-2002 09:16 PM).]

[CrystyB]

Bah, perseverance is not my middle name... Not at this time of the night anyway. Could someone please post in invisible the keyword so that i have to decypher the first message to sa i DID something?

[Tahnan]

I may have encoded my message backward. My strategy was--here, let me invisiblize it, it isn't the answer but it's a minor spoiler--to assume that any quote opening with a three letter word pertty much had to open with "THE." Of course, I was wrong. But once I got over that I did use the "repeated word" trick to get the length of the keyword and, guessing at one of the words, to get the keyword itself.

[Cadmium]

Thanx, Bar-one.

I couldn't find more repeated words though. So the keyword could still be 2, 5 or 10 letters long. Oh, and about grid...Is this what you meant?:

code:

---

   01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26


00  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z


01  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a


02  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b


03  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c


04  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d


05  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e


06  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f


07  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g


08  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h


09  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i


10  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j


11  l  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k


12  m  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l


13  n  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m


14  o  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n


15  p  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o


16  q  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p


17  r  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q


18  s  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r


19  t  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s


20  u  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t


21  v  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u


22  w  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v


23  x  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w


24  y  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x


25  z  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u  v  w  x  y

---

The numbers of the rows begin with 0 so you can read the number of steps. You can find the matching letter in row 00.

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Any similarities between what I say and what I mean are purely coincidental.

[bar-one]

Cadmium, I used a grid like this:

code:

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    |                      PLAINTEXT                     


    | a b c d e f g h i j k l m n o p q r s t u v w x y z


----|----------------------------------------------------


   a| b c d e f g h i j k l m n o p q r s t u v w x y z a


   b| c d e f g h i j k l m n o p q r s t u v w x y z a b


   c| d e f g h i j k l m n o p q r s t u v w x y z a b c


   d| e f g h i j k l m n o p q r s t u v w x y z a b c d


   e| f g h i j k l m n o p q r s t u v w x y z a b c d e


   f| g h i j k l m n o p q r s t u v w x y z a b c d e f


   g| h i j k l m n o p q r s t u v w x y z a b c d e f g


   h| i j k l m n o p q r s t u v w x y z a b c d e f g h


K  i| j k l m n o p q r s t u v w x y z a b c d e f g h i


E  j| k l m n o p q r s t u v w x y z a b c d e f g h i j


Y  k| l m n o p q r s t u v w x y z a b c d e f g h i j k


W  l| m n o p q r s t u v w x y z a b c d e f g h i j k l


O  m| n o p q r s t u v w x y z a b c d e f g h i j k l m


R  n| o p q r s t u v w x y z a b c d e f g h i j k l m n


D  o| p q r s t u v w x y z a b c d e f g h i j k l m n o


   p| q r s t u v w x y z a b c d e f g h i j k l m n o p


   q| r s t u v w x y z a b c d e f g h i j k l m n o p q


   r| s t u v w x y z a b c d e f g h i j k l m n o p q r


   s| t u v w x y z a b c d e f g h i j k l m n o p q r s


   t| u v w x y z a b c d e f g h i j k l m n o p q r s t


   u| v w x y z a b c d e f g h i j k l m n o p q r s t u


   v| w x y z a b c d e f g h i j k l m n o p q r s t u v


   w| x y z a b c d e f g h i j k l m n o p q r s t u v w


   x| y z a b c d e f g h i j k l m n o p q r s t u v w x


   y| z a b c d e f g h i j k l m n o p q r s t u v w x y


   z| a b c d e f g h i j k l m n o p q r s t u v w x y z

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Tahnan, lol @ invisiblize!

[Sami]

Thanks, bar-one! Since you encoded your message with my keyword, I guess you've solved the cipher. Not sure about Tahnan, though, since I can't decipher his message.