In the novel Mathias Sandorf by Jules Verne the use of a Turning Grille is described. Does a reader know other encrypted messages of this kind?
Italian cryptologist Luigi Sacco left behind a text encrypted with a Fleissner grille. Paolo Bonavoglia and Bart Wenmeckers, both readers of this blog, solved it.
The Fleissner grille is one of the most popular encryption tools. In spite of its popularity, surprisingly little has been published about deciphering a Fleissner grille. I wonder if a reader can break the Fleissner challenge I am going to present today.