A cipher disk introduced on Reddit looks like a mass-produced item from the 20th century. Does a reader have any information about this crypto tool?
In World War II German secret agents used a little known cipher device named Schlüsselrad (Cipher Wheel). An old document blog reader Ralph Erskine made me aware of contains the first photographs I have ever seen of this device, as well as some additional information.
A French museum has an unusual cipher device on display. Can my readers find out how it works?