You may find a good illustration of Data Encryption Standard algorithm(DES) on this link.
https://drive.google.com/open?id=0B_-L7kEES2VscERKbXRQbVdNdTA
https://drive.google.com/open?id=0B_-L7kEES2VscERKbXRQbVdNdTA
M.Sc. Graduate with research interest in Natural language processing, machine learning and pattern recognition.Currently Working as Lecturer at Central Department of Computer Science and IT in Tribhuvan University, Kathmandu.