When I was first learning about encryption and encoding, I was fascinated by the Nazi’s Enigma Machine. This device confounded Allied forces in the early days of World War II and is considered by some to be an ancestor of the modern computer.
It was a complex device with many dials and knobs, as well as a keyboards. A soldier had to be trained to use the device, and when used correctly it would encrypt a message in a manner that could only be decrypted by another machine.
Today, the concept can fit in your pocket. Mike Koss, local to me here in Seattle, makes these neat papercraft Enigma Machines. Using paper columns and slots to replicate the rotors of the original machine, users can encrypt and decrypt messages on the fly.
Not for everyone, sure, but our geekier readers are already downloading the PDFs.