### Instruction: Using the Playfair cipher, encrypt the message "MATH IS FUN" using the key phrase "CRYPTOGRAPHY". Show all steps in the encryption process.### Response: To encrypt the message "MATH IS FUN" using the Playfair cipher with the key phrase "CRYPTOGRAPHY", follow these steps:

1. Create a 5x5 grid using the key phrase and the English alphabet (excluding 'J', which is combined with 'I').

   Remove duplicate letters from the key phrase: CRYPTOGRAPYH -> CRYPTOGRAPHY
   Fill the grid:
   C R Y P T
   O G A H B
   D E F I K
   L M N S U
   V W X Z Q

2. Split the message into digraphs (pairs of letters). If a pair has the same letter, insert an 'X' between them. If the message has an odd number of letters, add an 'X' at the end.

   MATH IS FUN -> MA TH IS FU NX

3. For each digraph, apply the Playfair cipher rules:

   - If both letters are in the same row, replace them with the letters to their right (wrap around if necessary).
   - If both letters are in the same column, replace them with the letters below them (wrap around if necessary).
   - If the letters form a rectangle, replace each letter with the one in its row but in the other letter's column.

   MA -> (same row) -> OC
   TH -> (rectangle) -> YP
   IS -> (same column) -> KN
   FU -> (rectangle) -> GT
   NX -> (rectangle) -> ZD

4. Combine the encrypted digraphs to get the final encrypted message:

   OC YP KN GT ZD

So, the encrypted message using the Playfair cipher with the key phrase "CRYPTOGRAPHY" is "OCYPKNGTZD".