ISRO2018-46

Question

In cryptography, the following uses transposition ciphers and the keyword is LAYER. Encrypt the following message. (Spaces are omitted during encrypton)

$\text{WELCOME TO NETWORK SECURITY!}$

1. $\text{WMEKREETSILTWETCOOCYONRU!}$
2. $\text{EETSICOOCYWMEKRONRU!LTWET}$
3. $\text{LTWETONRU!WMEKRCOOCYEETSI}$
4. $\text{ONRU!COOCYLTWETEETSIWMEKR}$

Answer 1

Write the plaintext in rows of width l(length of Key) and read it off by columns. Take the columns in a order defined by a key.

Here, l = 5,

Keyword   = L A Y E R
Key       = 3 1 5 2 4

Plaintext = W E L C O
            M E T O N
            E T W O R
            K S E C U
            R I T Y !    

Ciphertext: EETSI C00CY WMEKR ONRU! LTWET      ANS:(b)   .

Comments

Keyword   = L A Y E R
Key       = 3 1 5 2 4

A comes at first in Alphabetic order so 1

E comes after A so E=2 

L comes after E so L=3 so on...

Answer 2

Option (B) is correct.

KEY IS - LAYER

Arrange the Message according to the Key in Alphabetical order.

Comments

Yes B is right

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what "according to" ...!!!

Answer 3

https://www.staff.uni-mainz.de/pommeren/Cryptology/Classic/8_Transpos/Examples.html

Read it from here and solve

Comments

B is correct