Mathematics and Cryptography is an interest of mine. Over the years, I have developed a few programs that tie into mathematics and cryptography in different ways.

Java

These are all java applets.

Rational Poly Graph
Source
This is a unique graphing plot I created from scratch. It is designed to plot any rational numbers Greater than 0 from a function you enter. The plot I created involves using square numbers for the position of pixels.
Ulam Grapher
Source
This is a unique graphing technique, for graphing polynomials and overlaying it with the ulam prime number spiral. The output of the iterated expression is drawn on the screen. For example, enter in x^2-x+41 and compute the polynomial.
Prufer Tree Viewer
Source
Ever heard of the prufer code? The app will display a visual representation of a Prufer code.

Python

FactHash

SourceForge.net Home Page
This is my first attempt at a one-way hashing algorithm written in python as a class. No idea if it’s actually a secure hashing algorithm until more research has been done.