Grille Method
The grille method, developed by Cardinal Richelieu in the 1600's, was a secret message
that could only be deciphered by a special card punched with holes in strategic locations.
It's still an effective method for sending secret messages today! The picture below shows a plain message and the associated grille card that is used to decipher
the secret message from the plain message.
Plain Message Secret Message Via Grille
You can create a grille message two different ways: Write a message and then create
a grill card just for that message; create a master grille card and write message
to fit within the predetermined hole punched locations.
In the example above the message was written out and the grille card was punched out
as needed to create the secret message. Since the message was fairly long it was
easy to get all the necessary characters to create the secret message "Meet me at
the church." However, the encipherer is now stuck with the problem of needing to create
a second grille card for their friend and must get both the grille card and the secret
message to their friend using separate means. Otherwise an enemy could intercept
the message and use the enclosed grille card to decipher it.
A better, but more complicated method, for creating a grille method is to make up
a set of master grille cards that have hole punches in the same location on each
card. Make sure you note which end is up on each of the card to ensure proper orientation.
Then you write a message so that the letters for your secret message land in the grille
punched locations.
Are there problems with this? What happens if you want to send a long message?