Write a program for Hill Cipher Method (Use 2 x 2 Matrix and 3 x 3Matrix)Note: (Optionsshould be given to user for Key matrix. it is either 2 x 2 matrix or 3 x 3 matrix)Hint: https://www.javatpoint.com/hill-cipher-program-in-javaBelow change is required in your submission:1. You have to take input as key matrix2. Entered matrix is square matrix or not, if not pls re-enter the matrix3.  Take input of plaintext is also in square matrix form for ex if 2 X 2 matrix is entered than plaintext should be 4 character, if matrix is 3X3 than plaintext should be 9 character like wise...Note: use padding if necessary

Here is a Python program for the Hill Cipher Method. This program will take a 2x2 or 3x3 key matrix as input and will check if the entered matrix is a square matrix. It will also take the plaintext as input in a square matrix form.

import numpy as np
from sympy import Matrix

def encrypt(message_vector, key_matrix):
    cipher_matrix = key_matrix.dot(message_vector)
    cipher_matrix = np.mod(cipher_matrix, 26)
    return cipher_matrix

def decrypt(cipher_matrix, key_matrix):
    key_inverse = key_matrix.inv_mod(26)
    message_matrix = key_inverse.dot(cipher_matrix)
    message_matrix = np.mod(message_matrix, 26)
    return message_matrix

def main():
    size = int(input("Enter the size of the key matrix (2 or 3): "))
    if size not in [2, 3]:
        print("Invalid size. Please enter 2 or 3.")
        return

    print("Enter the elements of the key matrix:")
    key_matrix = []
    for _ in range(size):
        row = list(map(int, input().split()))
        if len(row) != size:
            print("Invalid matrix. Please enter a square matrix.")
            return
        key_matrix.append(row)

    key_matrix = Matrix(key_matrix)
    if key_matrix.det() == 0:
        print("Invalid key matrix. Determinant is 0.")
        return

    message = input("Enter the plaintext (length should be a multiple of the matrix size): ")
    if len(message) % size != 0:
        print("Invalid plaintext length. It should be a multiple of the matrix size.")
        return

    message_vector = [ord(c) - ord('A') for c in message.upper()]
    message_vector = np.array(message_vector).reshape(-1, size).T

    cipher_matrix = encrypt(message_vector, key_matrix)
    print("Encrypted text: ", ''.join(chr(c + ord('A')) for c in cipher_matrix.flatten()))

    message_matrix = decrypt(cipher_matrix, key_matrix)
    print("Decrypted text: ", ''.join(chr(int(round(c)) + ord('A')) for c in message_matrix.flatten()))

if __name__ == "__main__":
    main()

This program uses the numpy and sympy libraries for matrix operations. The encrypt function encrypts the message using the key matrix, and the decrypt function decrypts the cipher using the inverse of the key matrix. The main function takes the key matrix and plaintext as input, checks if they are valid, and then calls the encrypt and decrypt functions.