Write a C program that decrypts a file named encrypted.txt and places the decryption output to a file called decrypted.txt. A file encrypted with k = (5, 7) is provided with the assignment. You can use it to test your decryption function. You will know when you have succeeded because the text becomes readable.

1 Affine Cipher (70 points) The Affine cipher is a cryptographic method for encrypting text such that it becomes unreadable to a party without access to the cryptographic key. The encryption and decryption operations are simple shifts of the alphabet letters in a cyclic fashion. Mathematically, for a key k (a, B), the encryption and decryption are defined as: Encryption: c = (a-z+ ) mod 26 , 1