Hi,

I have not programmed for at least 6+ years and am looking to try to get back into it.

How can i implement the encryption and decryption as used in DES.

The program should ideally receive a message or open a file to encrypt it or decrypt it. it should also receive a DES key.

Both encryption and decryption operations are the same with one exception in the sequence in which the sub keys are used. If in encryption subkeys 1 to 16 are used then in encryption the subkeys 16 to 1 are used.

The program should receive a key and a file to encrypt and it should produce a encrypted file. It should also have some option to receive the encrypted file and they key, and it should decrypt it and produce the original file again.

Any tips or help would be great as i have alot to learn to get back into programming.