Codes And Ciphers

#17 Polyalphabet Code

#Cryptography

LECTURE #24: COLUMNAR TRANSPOSITION

[INTRODUCTION]
Columnar transposition is a type of transposition cipher, this uses columns to create an encrypted message by using a given key.

[ALGORITHM]
In a columnar transposition, the message is written out in rows of a fixed length, and then read out again column by column, and the columns are chosen in some scrambled order. Both the width of the rows and the permutation of the columns are usually defined by a keyword.

[ENCRYPTION]
You are to cipher the message "The Honour is within us" and your key would be "BEHOLD"
Since, the Key has 6 letters.

— Write your message in 6 columns.
Ang paglalagay ng message ay from left to right then down, so on and so forth.
Remember this.
Then, magiging ganito siya:
T H E H O N
O U R I S W
I  T H  I N U
S X X X X X
(Note: The X's are nulls to balance out the message)

— Now that we have 6 columns.
Now put the key: "Behold" on top of it,
Para maging ganito:
b e  h o  l  d
T H E H O N
O U R I S W
I  T H  I N U
S X X X X X

— So each columns at may keys na. For column 1 letter B, For column 2 letter E and so on and so forth.

— Ngayon leave the message and rearrange the key: "BEHOLD" number it from 1 to 6 BASED on the Alphabetical places.
B = 1
E = 3
H = 4
O = 6
L = 5
D = 2

— Kung ilalapat natin ulit ang message at gagamitin ang numberings.
It would be like this:
1 3  4 6  5  2
T H E H O N
O U R I S W
I  T H  I N U
S X X X X X

— Now, to be able to cipher it fully.
REARRANGE THE COLUMNS FROM 1 - 6
Kaya magiging:
1 2  3 4 5  6
T N H E O H
OW U R S I
I  U T H N I
S X X X X X

— Then list down the ciphered text like this. (Still in the numerical 1 - n)
"TOISNWUXHUTXERHXOSNXHIIX"
↑ So, this is your Encrypted message, using Columnar disposition.

[DECRYPTION]
Keyword: CIPHR
Encrypted Message:
'ALETIFWMFDVLLMEEOLYNEWERX'

Reverse the process.

— Hatiin ang buong message according sa letters ng Key. CIPHR = 5 letters. So magiging:
ALETI FWMFD VLLME EOLYN EWERX

— List every 5-letter group in columns, bawat group isang column at isusulat sa left side muna  mula sa taas pa baba, then next group naman, mula sa taas baba and so on and so forth.
like this:
A F V E  E
L W L O W
E M L L  E
T F M Y R
I  D E  N X

— Leave it for a while and work on the key: CIPHR.
Ayusin niyo yung code in Alphabetical order to obtain this: CHIPR

— Now place the alphabetical ordered key at top.
c h  i  p   r
A F V E  E
L W L O W
E M L L  E
T F M Y R
I  D E  N X

— Ngayon may kaakibat na column na ang alphabetized key, irearrange sa original key kasama ang letters sa column nito. To obtain this:
c  i  p h  r
A V E F  E
L L O W W
E L  L  M E
T M Y F  R
I  E  N D X

— List it down by rows.
AVE FELLOW WELL MET MY FRIEND X
(Note: X is use to be a null)

DECIPHER MY MESSAGE TO ALL OF YOU:
"BAENYCUETEODOXIIIEATXENLTAOSSNGLNEXWDLBLRX"

Credits to: Potato Queen 👑 (Jabez Chzammuth Tumbaga)