I’m personally hostile to analogies and “dumbing down”, because it can have the unintended effect that people take the analogy too far, or get stuck with the dumbed down version.

Your goal is to show the complexity, but without overwhelming the audience. You can do that by providing multiple layers.

In the main part of the text, speak mostly about consequences, leave out technical details: Encryption ensures the confidentiality of documents because knowledge of a key is needed to decrypt and thus read the document. This layer is written for the non-technical audience and should require no technical knowledge to understand. You would explain, say, the difference between encryption, hashing and cryptographic s