UGC NET CSE | Junet 2015 | Part 3 | Question: 28

Question

A message "COMPUTERNETWORK" encrypted (ignore quotes) using columnar transposition cipher with a key "LAYER". The encrypted message is

• A. CTTOEWMROPNRUEK
• B. MROUEKCTTPNROEW
• C. OEWPNRCTTUEKMRO
• D. UEKPNRMROOEQCTT

Comments

Algorithm for simple columnar transposition technique with multiple round

1. write the plain text msg row by row in a rectangle of a predefined set

2. Read the msg column by column. However it nedd not be any order of column 1, 2,3 etc. it can be any random order such as 2,3,1 etc

3. The msg thus obtained is cipher text msg of round 1

4. Repeat step 1 to 3 as manytime as desired.

Answer 1

this one is simple and intersting  just make the colum arrangement as below

3    1   5    2   4

L    A   Y   E   R    (assign number from 1 onwards as per aplhabetical order e.g A=1 E=2.....) IGNORE ""

C   O   M   P   U

T    E   R   N   E

T    W  O   R   K

S

NOW write all letters of column 1 then 2  3,4,5  and ans will be OEWPNRCTTSUEKMRO

Comments

Should we expect these type of qiestions in Gate ?

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This  belongs to cryptography and already came in ugc net exam so why not

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Thanks :)