Cardan grille
= Cardan grille
{wiki=Cardan_grille}
A Cardan grille, also known as a Cardan grid or Cardan caché, is a cryptographic tool or device used for encoding messages. It consists of a rectangular grid or a series of grids with one or more holes cut into it. The basic idea is that the grille is placed over a piece of text, and the holes in the grille align with certain letters of the text, allowing some letters to be visible while covering others.