Information Security: Principles and Practices 2nd Edition by Jim Breithaupt, Mark S. Merkow

Exercise 1

Practicing Encryption Using Transposition

1. Encrypt the following message using the keyword CAUTION and the transposition method:

MARCH FORWARD INTO THE NIGHT TUESDAY NEXT

2. What result did you get?

Step 1 of 2

Creating cipher text using Transposition method

1. Transposition is a method of encryption wherein a plaintext is converted into a cipher text. This makes the data to be sent more secure as data in encrypted form is difficult to read and understand. Also it is hard to decode.

In transposition method, the basic idea is to rearrange the letters of the word (data) in some different order such that it becomes unreadable.

Given the keyword CAUTION, the message “MARCH FORWARD INTO THE NIGHT TUESDAY NEXT”, needs to be encrypted using Transposition method. The steps to create the encrypted text from the given plaintext are shown below:

Step 1: Write the given keyword in horizontal manner as shown below:

C A U T I O N

Step 2: Assign numeric value to each of the letters of the keyword in the order in which they appear in the alphabetical series as shown below:

C A U T I O N

2 1 7 6 3 5 4

Step 3: The given plaintext is aligned across each key one letter at a time horizontally. This is shown below:

C A U T I O N

2 1 7 6 3 5 4

M A R C H F O

R W A R D I N

T O T H E N I

G H T T U E S

D A Y N E X T

Step 4: Finally, read and club the letters of each column and list them according to the ordinal value of the column such that A-1 is column 1, C-2 is column 2, I-3 is column 3, and so on. This is shown below:

AWOHA MRTGD HDEUE ONIST FINEX CRHTN RATTY