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Wolfram Demonstrations Project
The Wolfram Demonstrations Project Goes 7
A Demonstrations Project Update
Secret Codes in the Wolfram Demonstrations Project (But No Dinosaurs)
Recent Demonstrations: Visual Encryption
When I was a kid, dinosaurs and secret codes were topics of surefire interest, since one was useful for eating your little sister and the other one for denying her the password to the clubhouse. I haven't noticed any Demonstrations about dinosaurs yet (I continue to keep an eye out), but interesting ones about cryptography turn up regularly, including a couple of neat recent entries on visual encryption: Michael Schrieber's Visual Encryption Pad and Paul van der Schaaf's Graphical Modulo-4 Image Encryption.
One cipher (if you can call it that) common in my kiddie code books involved printing a message in red stipple overlaid with a noise field of blue stipple. You could use the piece of red cellophane included in the back of the book to mask out the blue part and reveal the secret message. The Visual Encryption Pad Demonstration is the sophisticated cousin of this scheme, involving the overlay of a random bit mask (the key) with another bit mask of the same size (the message). Applying a set of rules to the combination of bits at a given pixel (in the case of this Demonstration, XNOR) reveals the message, which might look like this:
If your spies in the field don't have computers, and you are limited to passing around messages on microfilm or something, then the only bit-combination rule set you will be able to use is OR. And of course your messages are limited to one bit per pixel. The Graphical Modulo-4 Image Encryption> scheme, on the other hand, can encode more than one bit per pixel, even on physical media. Let me quote some snippets of the Demonstration's code and describe how they work, and then I'll discuss a couple of extensions that suggest themselves.The Form of a Form
Decorating Eggs with Mathematica
Adventures in the Wolfram Demonstrations Project
Demonstrating Valentine’s Day
Broken Heart Tangram | A Rose for Valentines Day |
Equations for Valentines | Sweet Heart |
The Polar Equations of Hearts and Flowers | Cupid's Arrow |
Gizmos, Gadgets and Gears
I do love gadgets, linkages, clockworks, all that 19th-century cogs-and-wheels technology. So much easier to see than our 21st-century nanotubes and zillion transistors on a chip.
Sándor Kabai has written many Demonstrations illustrating such mechanisms.
What makes these interesting is that playing with the various parameters lets you vary both the geometric setup and the controls that make the mechanism go through its motion.