Language: Java

1 Details of the program

You need to do the following tasks:

1. Implement a function that computes the inverse of a 3x3 matrix mod 26 (Hint: you can use lookup table to nd the multiplicative inverse mod 26).

x 1 3 5 7 9 11 15 17 19 21 23 25

inv(x) 1 9 21 15 3 19 7 23 11 5 17 25

2. Implement a function that computes the inverse of a 3x3 matrix (K) mod 26. Specifically, you need to compute the determinant and the cofactors for the construction of K^-1

3. Implement encryption/decryption functions for 3x3 Hill Cipher (Hint: your encryption function should be general enough to hand any length of text. You should add one or two xx if it is not divisible by 3.

4. Using the following key

4 9 15

k= 15 17 6

24 0 17

(a) Invoke your inverse function and print out the inverse of the above key K (mod 26).

(b) Invoke your encryption function to print out the cipher text, given the above key and the plaintext of "paymoremoney".

(c) Invoke your decryption function to print out the plaintext using the cipher text above.

5. Using the following key

1 2 3

K = 4 5 6

7 8 10

(a) Invoke your inverse function and print out the inverse of the above key K (mod 26).

(b) Invoke your encryption function to print out the cipher text, given the above key and the plaintext of "hillcipherisfuntome".

(c) Invoke your decryption function to print out the plaintext using the cipher text above.