Crytpography Demos

Encryption is a way of hiding secrets by applying mathematical functions to plain text to produce text that is difficult to decrypt. This module describes the mechanics of the DES (Data Encryption Standard) using serveral Java applets. Other facets of encryption are also demonstrated.

The first version of the cryptography module will include history, standards and evolution, an overview of the DES algorithm, keysize issues, confusion and diffusion, block size, key size, number of rounds, subkey generation algorithm, the avalanche effect, cryptanalysis, Feistel structures, round functions, S-boxes, and harware encryption vs. software encryption. As is, the module may be used by an instructor familiar with the concepts of cryptography needing some interactive demonstrations for classroom or laboratory work.

DES Demo Applets: 
 

• A java applet that demonstrates diffusion in S-DES
• A java applet that demonstrates diffusion in the round function for S-DES
• A java applet that demonstrates key generation in S-DES
• A concise explanation of confusion
• A step-by-step demonstration and explanation of differential cryptanalysis on an 8-bit, three round block cipher similar to S-DES
• A step-by-step demonstration of linear cryptanalysis on the same block cipher
• C code and Linux script for differential cryptanalysis
• C code and Linux script for linear cryptanalysis


Related Cryptography Applets: 

Other demonstrations for the cryptography module focus on hash functions. These javascripts don't yet perform the hash function but they do give a good explanation of padding:
 

• A generic hash function demonstration
• An MD5 demonstration
  A SHA1 demonstration

 

Contacts: Questions, comments, or  feedback to Dr. Susan Gerhart.  Authors: Dr. Paul Hriljac (on sabattical, Sweden, until November 2002), students J. R. Crandall, Eric Fikus, Nathanial Alderson.

Background reading: For a good background reading on DES see Cryptography and Network Security: Principles and Practice by William Stallings