For the described three-step symmetric encryption (in-word letter swap, A/E swap, then a Caesar shift of 14), what would be the best key to explain the method to a friend?

For the described three-step symmetric encryption (in-word letter swap, A/E swap, then a Caesar shift of 14), what would be the best key to explain the method to a friend?

• A. The original plaintext before encryption.
• B. A random number used to seed the random generator.
• C. A diagram of Caesar shift by 7.
• D. A 3-step explanation of how he encrypted the message (the in-word letter swap, the A and E swap, and the Caesar shift of 14).

Answer: (D)

A good key for explaining this encryption is a clear, three-step description of the method—covering the in-word letter swap, the A/E swap, and the Caesar shift by 14—so your friend can reproduce it. This kind of explanation directly conveys how to apply the system, which is what a key should do: it describes how the encryption is performed, not just what one part looks like. Revealing the original plaintext isn’t a key at all because it exposes the message instead of teaching the method. A random seed is an implementation detail that doesn’t describe the steps themselves, so it doesn’t help someone understand how to encrypt and decrypt. A diagram of a Caesar shift by 7 gives only a single piece and even uses the wrong shift amount, so it wouldn’t accurately convey the full three-step process. Describing the exact sequence of steps and the specific shift makes the method understandable and reproducible.

A good key for explaining this encryption is a clear, three-step description of the method—covering the in-word letter swap, the A/E swap, and the Caesar shift by 14—so your friend can reproduce it. This kind of explanation directly conveys how to apply the system, which is what a key should do: it describes how the encryption is performed, not just what one part looks like. Revealing the original plaintext isn’t a key at all because it exposes the message instead of teaching the method. A random seed is an implementation detail that doesn’t describe the steps themselves, so it doesn’t help someone understand how to encrypt and decrypt. A diagram of a Caesar shift by 7 gives only a single piece and even uses the wrong shift amount, so it wouldn’t accurately convey the full three-step process. Describing the exact sequence of steps and the specific shift makes the method understandable and reproducible.