Pretty Printer

I had done a pretty printer for Relax NG form Scala which is run on top of the Java and it is very much similar to Java. You can download the source code from following URL, and within the Pretty Printer.zip file contains info.txt file describing how to run this application.

http://cid-7c26d771289f240d.skydrive.live.com/self.aspx/.Public/Pretty%20Printer/Pretty%20Printer.zip

Playfair Cipher

see this link
http://rumkin.com/tools/cipher/playfair.php

See Following Sites To Learn Cryptography

http://en.wikipedia.org/wiki/Cryptography
http://world.std.com/~franl/crypto.html
http://axion.physics.ubc.ca/crypt.html