Which cipher uses a grid-based system to substitute letters with symbol fragments?

• A. Pigpen Cipher
• B. Caesar Cipher
• C. One Time Pad
• D. Asymmetric encryption

Answer: (A)

This question tests recognizing a cipher by how it substitutes letters with symbol fragments drawn from a grid. The Pigpen cipher uses geometric grid patterns—typically two 3x3 grids (and two X-shaped grids)—to map each letter to a specific line segment or plus a dot to distinguish the second set. The result is letters replaced by visual fragments of the grid, not by ordinary letters.

That’s why this is the best choice: it’s the classic example of grid-based substitution where symbols come from the grid’s shapes rather than from a simple alphabetic shift or a key-based binary operation. In contrast, the Caesar cipher shifts letters along the alphabet, not via grid fragments; the One Time Pad produces ciphertext through a random key stream and modular addition rather than grid symbols; and asymmetric encryption uses public/private keys and distinct algorithms, not a fixed grid substitution.