Classical cryptography is the best starting point for
learning cryptosystems without prior knowledge of cryptography and high
level mathematics. Here we will selectively review classical
cryptosystems. By classical cryptography we mean the cryptosystems are
pencilandpaper based and used until the middle of twentieth century. We
have included shift, affine, simple substitution, transposition, Hill and
Vigenère ciphers. We have included extensive looks at each of these
cryptosystems, touching on categories such as a basic description and
history of the cipher, the advantages and disadvantages of using the
cipher, and examples to demonstrate how the encryption and decryption
works for each type.
Along with the written elements, we have also included
interactive demonstrations of the cryptosystem. The JavaScript and Java
Applet demos
should help exemplify the advantages and disadvantages of each cipher.
