Cardan grille

That about the year 1550 by the Italian mathematician Gerolamo Cardano invented, named after him, " Cardan grille " played a significant role in the encryption of messages in the early modern period. From the perspective of modern cryptography is a Steganographieverfahren.

On a writing pad ( parchment, paper, etc.), a grid is drawn. Some of the fields of the table thus formed are then cut out of the carrier. This creates a " perforated template ", ie a template, here a so-called individual Cardan grille.

To encrypt a text using the template now, the individual Cardan grille is placed on a blank piece of paper, and only at the points where the template " full of holes ", the exploded word pieces, syllables, letters, or other transcriptions message entered. The rest of the table may be filled with arbitrary data.

To decrypt the message you need the individual Cardan grille.

Nowadays, the functionality of the Cardan grating will often used in connection with the steganography.