A technique used to encrypt plaintext by writing it onto a sheet of paper through a pierced (or stenciled) sheet of paper, cardboard, or any other similar material.

A technique used to encrypt plaintext by writing it onto a sheet of paper through a pierced (or stenciled) sheet of paper, cardboard, or any other similar material.

• A. Open Codes
• B. Jargon Codes
• C. Image Steganography
• D. Grille Ciphers

Answer: (D)

This is describing a grille cipher, also known as a Cardan grille. The core idea is to control exactly where letters are written by using a stencil with holes. You place the pierced sheet over blank paper, write the plaintext through the open holes, then move or rotate the stencil to reveal new holes and continue writing. The final sheet shows letters packed into positions according to the grille’s pattern, so the message is scrambled unless you use the same grille (or its exact rotation sequence) to read it in the proper order. This physical masking and subsequent rearrangement of characters is what gives grille ciphers their distinctive encryption method. It’s different from image steganography, which hides a message inside another medium like an image, and it isn’t simply “open” or “jargon” codes, which aren’t standard terms for this technique.

This is describing a grille cipher, also known as a Cardan grille. The core idea is to control exactly where letters are written by using a stencil with holes. You place the pierced sheet over blank paper, write the plaintext through the open holes, then move or rotate the stencil to reveal new holes and continue writing. The final sheet shows letters packed into positions according to the grille’s pattern, so the message is scrambled unless you use the same grille (or its exact rotation sequence) to read it in the proper order. This physical masking and subsequent rearrangement of characters is what gives grille ciphers their distinctive encryption method. It’s different from image steganography, which hides a message inside another medium like an image, and it isn’t simply “open” or “jargon” codes, which aren’t standard terms for this technique.