### Simplified DES Calculator (SDES), v1.0

Simplified DES (SDES) is a "toy" symmetric encryption algorithm created by Ed Schaefer.
It is meant for instructional purposes as a companion to Data Encryption Standard (DES).
The idea is to impart a feeling for the *real* DES without the large amount of computation
that is required of industrial-strength DES.
Still, computing SDES can be error-prone and tedious. This calculator will do the
necessary computations, while exposing each and every intermediate result on request.
With this tool, a student can work out examples by hand (which is preferable in this case)
while checking the intermediate steps so that errors do not propogate.

A group of students might also use this calculator for a distributed brute-force
attack on SDES when given pairs of plaintext and ciphertext all generated with the same key.
The 10-bit key size might allow for reasonable size partitions if each student is asked to
check all possible keys with the first few bits fixed.

The interested user should consult one of the references below for a complete
treatment of SDES. I've relied mostly on Stallings during development.

References:

- Barr, Invitation to Cryptology, 1st edition, Prentice Hall, 2002
- Schaefer, E. "A Simplified Data Encryption Standard," Cryptologia, January 1996
- Stallings, William. "Cryptography and Network Security", 2nd Edition

### SDES Calculator

### Getting the software

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

GNU Public License Information

Source and class files are available here for download as a JAR file.

Rob Beezer, BEEZER(at)UPS(dot)EDU, Updated:
May 22, 2003