C program that encrypts alphabetic letters using Hill cipher

You'll write a program that encrypts the alphabetic letters in a file using the Hill cipher. Your program should prompt the user for the names of two input files and one output file: 1) The file storing the encryption key 2) The file to be encrypted 3) The corresponding encrypted file Your program should open the first two files, make the necessary calculations and write the ciphertext to the third file. If the file to be encrypted doesn't have the proper number of alphabetic characters, pad the last block as necessary with the letter 'X'. The rest of the instructions have been attached. Please follow all attached instructions and final program should compile and execute in C. After the program is completed please include a report that briefly describes the design of your program. Also describe the test data you used in testing your program. Thanks