Write a program that implements the full DES. Use the S-boxes that are specified for the DES standard (See page 4). Make sure you implement all of the key generation steps outlined on page 7. For the encryption key, your script should prompt the user for a keyboard entry that consists of at least 8 printable ASCII characters. (You may choose to either use the first seven or the last seven bits of each character byte for the 56-bit key you need for DES.) What makes this homework not as difficult as you think is that once you write the code that carries out one round of processing, you basically use the same code in a loop for the whole encryption chain and the decryption chain. Obviously, you will have to reverse the order in which the round keys are used for the decryption chain.