Blog reader Christoph Tenzer has solved the Rubik’s Cube challenge I introduced last October. His work is an amazing act of cryptanalysis.

A Rubik’s Cube can be used to implement a low-tech encryption method. But is it secure? Here’s a challenge for my readers to solve.

A Rubik’s Cube can be used to define a crypto system that cannot be broken with quantum computers. Here’s a puzzle that shows the concept this system is built on. Can you solve it?

A Rubik’s Cube can be used to implement a highly secure encryption method.