MW Codes, Ciphers, and Puzzles Series: Keyword Ciphers

This segment of the MW Codes, Ciphers, and Puzzle Series features the Keyword Cipher.  The Keyword Cipher is similar to the Caesar Shift Cipher in that the alphabet is shifted; but instead of being shifted by a certain number, it is shifted by the use of a Keyword.

For example, if the Keyword is TREASURE for encoding/decoding a message, the keyword is placed at the beginning of the alphabet to match letters, without duplicates, and then followed by the remaining letters as shown below.

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

T

R

E

A

S

U

B

C

D

F

G

H

I

J

K

L

M

N

O

P

Q

V

W

X

Y

Z

So the ‘Secret Message’ of ‘We leave at daybreak’ is encoded ‘WS HSTVS TP ATYRNSTG’.

To decode the message, reverse the process.

This is the simplest form of Keyword Cipher.   Variations to the Keyword Cipher can be used, though.

One example of variation for this type of Cipher was used in the armchair treasure hunt book, The Ultimate Quest.  Although this hunt is discontinued and remains unsolved, some of the codes in the book were decoded.

One of which used the Keyword, JAMES DEMOLAY THE GRAND MASTER.  This keyword is 26 letters long, and so it was used to replace the entire alphabet.  Duplicate letters were present.

The code within the book was shown as follows:

ODN DOTS NJOE DMS YJSTJH AMD SMSH MS JHHEMHMSE ODDE DMS YJEE NMS DEAAJE ESEAES DEESD JHEAE OH DMONNOY SHD GYJMS.

There were a few clues within the book that might have suggested using such a Keyword.  To break the code, a trial and error attack, while using frequency analysis, and hopes for keyword discovery, is basically all that could be done to decode it.

Normally, in Armchair Treasure Hunts, there are clues on how to break a code or what system is used.  If a 26 letter phrase is used as a Keyword, the entire phrase may seem out of place, or various words creating a 26 letter phrase may be hinted towards.   Be on the lookout for such things, or ’26’ of anything.  It could use this type of Keyword Cipher.

As mentioned, there were duplicate letters in the Keyword found and used in The Ultimate Quest’s puzzle.  The A, M, E, S, D, T, and R are all used more than once.  When decoding, a searcher had to ‘try’ each letter they matched to determine the correct hidden message.

The decoded message was:

Its time said the lawman but when he announced itto the lady she forbad George toget angry in thissil ent place.

Yes, a searcher still had to determine what the message meant after it was decoded.  Lol.   The answer has never been given.

Such is the fun of armchair treasure hunting!