Which method uses a perforated or stencil sheet of paper to encrypt plaintext into a hidden message?

• A. Image Steganography
• B. Semagrams
• C. Linguistic Steganography
• D. Grille Ciphers

Answer: (D)

A grille cipher uses a perforated stencil to hide text. In this method you have a Cardan grille, a sheet with holes cut out. Placing it over a blank page, you write the plaintext through the openings. When you lift the grille, the letters appear only in those hole positions, effectively concealing the message in a random-looking arrangement. To add more characters, you rotate or reposition the grille and continue writing through the holes; the complete plaintext can then be recovered by overlaying the grille again. This is a classic physical masking approach to hidden writing, distinct from image-based hiding techniques or linguistic or diagram-based concealment.