Mathias-Sandorf-bar

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?

Bruce-Kallick-Handycipher-bar

Designing a secure and convenient encryption algorithm that doesn’t require a computer program or a machine is quite a challenge. The Handycipher is an interesting method of this kind.