Question

Using the Playfair cypher algorithm, encrypt the message "COMPUTERSECURITYEXAM". Consider your first name as the key. Show your work step-by-step

Answer 1

To encrypt a message with the Playfair cipher, create a 5x5 matrix with a key followed by the rest of alphabet, combine 'I' and 'J', create digraphs from the message, and apply Playfair rules to each digraph. A specific encryption example cannot be provided without the actual key.

Step-by-step explanation:

The student has asked for help encrypting the message "COMPUTERSECURITYEXAM" using the Playfair cipher algorithm with their first name as the key. The Playfair cipher is a manual symmetric encryption technique and was the first digraph substitution cipher.

To encrypt a message using the Playfair cipher, you first need to create a 5x5 matrix of letters using the key (the student's first name, which is not provided), followed by the rest of the unused letters in the alphabet. In the English alphabet, 'I' and 'J' are typically combined in the matrix to maintain a 5x5 layout.

Here's an example using a generic name 'ALICE' as the key:

1. Place the letters of the key 'ALICE' (removing any duplicates) in the matrix from left to right, top to bottom.
2. Fill the remaining spaces with the rest of the alphabet (excluding 'J').
3. To encrypt the message, divide it into digraphs (groups of two letters). If a digraph has a repeating letter, insert an 'X' between them. Add an 'X' at the end if necessary to complete the final digraph.
4. For each digraph, locate the letters in the matrix and apply the Playfair cipher rules to encrypt it.

Without the specific key, the exact encryption can't be completed, but this outlines the necessary steps to use the Playfair cipher.