A message "COMPUTERNETWORK" encrypted (ignore quotes) using columnar…

Solution:

Step 1: Write the key and determine alphabetical order of its letters.

• Key: LAYER

• Alphabetical order of key letters: A, E, L, R, Y

Step 2: Write the plaintext COMPUTERNETWORK into rows under the key (5 columns).

• Row 1 (under L A Y E R): C O M P U

• Row 2 (under L A Y E R): T E R N E

• Row 3 (under L A Y E R): T W O R K

Step 3: Read the columns in alphabetical order of the key letters (A, E, L, R, Y).

• Column under A: O E W

• Column under E: P N R

• Column under L: C T T

• Column under R: U E K

• Column under Y: M R O

Final ciphertext (concatenate the columns in that order): OEWPNRCTTUEKMRO