What Type of Cipher Uses a Hole-Punched Plastic Template?
Heather, a computer forensics investigator, is assisting a group of investigators working on a large computer fraud case involving over 20 people. These 20 people, working in different offices, allegedly siphoned off money from many different client accounts. Heather responsibility is to find out how the accused people communicated between each other. She has searched their email and their computers and has not found any useful evidence. Heather then finds some possibly useful evidence under the desk of one of the accused. In an envelope she finds a piece of plastic with numerous holes cut out of it. Heather then finds the same exact piece of plastic with holes at many of the other accused peoples desks. Heather believes that the 20 people involved in the case were using a cipher to send secret messages in between each other. What type of cipher was used by the accused in this case?
Community Votes
100% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
The exam tests recognition of a grille cipher from its physical hole-punched template; the trap is choosing null cipher because it also conceals a message in plain text.
A plastic sheet with holes cut out and found at multiple suspects' desks is a grille cipher template, not a null cipher or semagram. This page establishes option A as the answer and explains how the Fleissner-style overlay reveals hidden letters.
Most learners pick null cipher since it hides data in ordinary text, but a null cipher uses positional selection in the cover message and leaves no plastic overlay to find.
Community Discussion (3 comments)
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Expert Analysis
Why the Answer Is Correct
The evidence describes a physical sheet of plastic with numerous holes cut out, and identical sheets were found at multiple suspects' desks. That is the defining hardware of a grille cipher, often called a Fleissner grille: the sender and receiver place the same template over a cover text so only the letters visible through the holes carry the secret message. The matching templates explain how twenty people in different offices could share a common decoding method without sending obvious key material through email. Option A's spelling “Grill” is a common variant or typo for “grille,” not a different cipher family.Why the Other Options Are Wrong
A null cipher hides a message in an ordinary-looking text by selecting letters at fixed positions, for example every nth letter, and needs no plastic overlay, so the hole-punched object remains unexplained. A text semagram conveys a message through subtle textual formatting such as spacing, font changes, or punctuation patterns, again without a physical template. A visual semagram hides meaning in images, symbols, or drawings rather than in a card that reveals letters through cut-outs. None of those methods accounts for identical hole-punched plastic sheets being recovered from many desks.Community Comment Notes
Commenters converge on option A and describe the same physical mechanism; as 044f354 puts it, a grille cipher “uses a physical template (like the plastic piece with holes)”. aqeel1506 similarly describes “a card or plate with holes cut out” that is placed over a message to reveal the encrypted text. Elb reinforces the identification by pointing to Fleissner grille material, matching the scenario's hole-punched sheets. No commenter offers a credible case for the null cipher or either semagram option.Exam Strategy
When a question describes a recovered physical object, identify the cipher family by its tooling before reading the options. A hole-punched card or sheet should immediately point to a grille or Fleissner template, not to text-based steganography.
Frequently Asked Questions
Why is a null cipher not the right choice for the hole-punched plastic?
A null cipher selects hidden letters from a cover text by position and needs no physical overlay. The recovered plastic template is the distinctive tool of a grille cipher.
Why do identical hole-punched templates at multiple desks support a grille cipher?
A grille cipher requires sender and receiver to use the same hole pattern. Finding duplicates at many suspects' desks shows a shared decoding template rather than ordinary text steganography.