Hardware Design and Software Simulation for Four Classical Cryptosystems

The classical Cryptosystems are very old cryptosystems that were primarily used in the pre-computer era. They are considered weak nowadays and too easy to break, especially with computers. However, these simple cryptosystems give a good illustration of several of the important ideas of the cryptography and cryptanalysis's Systems. They are considered as the heart of cryptography science and its good to start with. In this paper, we arc going to design several cryptosystems using lava programming language such as shift cipher, affine cipher and others. in addition, we will practice on several number theory algorithms especially the modular arithmetic and prime numbers as well as on decomposing a large problem into modules and testing a circuit that is too large to test exhaustively. The software can be used then to send and receive an encrypted messages using the email systems. Moreover, a hardware design for Caesar and Affine Ciphers will be simulated via Multisim software and implemented using the logic gates and circuits and the skills learned from digital logic design course. (C) 2013 The Authors. Published by Elsevier B.V.