Question

What will be the encrypted text corresponding to plain text “CLASSIFIED” using columnar transposition cipher with a keyword as “GAMES”?

(a) LFDSIASECI

(b) SECIAISDFL

(c) CILFAISESD

(d) LFSECIAISD

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Question is from Cryptography in section Cryptography of Data Structures & Algorithms II

Answer 1

The correct answer is (d) LFSECIAISD

Easiest explanation - For encrypting using columnar cipher we have to arrange the letters of the plain text in a table which has the same number of columns as the letters of the keyword. Then the letters of the keyword are arranged in alphabetical order and we read along each column.

3 1 4 2 5

G A M E S

C L A S S

I F I E D

So the ciphered text will be “IFSECIAISD”.