Exam 312-49v10 topic 1 question 224 discussion

A grill cipher is a type of cipher that uses a card or plate with holes cut out to reveal specific letters or symbols on a message. The card is placed over the message, and the letters visible through the holes are the encrypted text. In this case, the plastic piece with holes found at each of the accused persons' desks is likely the grill cipher used to decode the secret messages. The other options are not correct: B. Null cipher: a cipher where the plaintext is hidden in plain sight, often using invisible ink or microdots. C. Text semagram: a cipher that uses a combination of letters and symbols to convey a hidden meaning. D. Visual semagram: a cipher that uses images to convey a hidden meaning. Heather's discovery of the identical plastic pieces with holes at each of the accused persons' desks suggests that they used a grill cipher to communicate secretly, and she can now use this evidence to decipher the messages and build a stronger case against them

A > https://www.instructables.com/Fleissner-Grille-Cipher/