No, non-techies do not "understand what encryption is". They'll understand if you explain it to them, but if you ask someone off the street what encryption is, the closest to a correct description they may give you is "it's garbled text you can decrypt".

It's hard enough to explain the easy, obvious stuff like tax brackets. You think people have a native understanding of encryption?

> You think people have a native understanding of encryption?

It’s easy. Tell people they’re speaking English to one other person who also speaks English at a dinner table. No one else in the world speaks English. You can look and sound like you’re talking about how excellent the food is, but really you’re saying how terrible it is... and no one on earth will ever know, other than the one person who understands you.

This is not a good way to explain encryption to people. Explaining the concept of a "key" is essential to explain why this doesn't work.

- In your example, the contents can be deduced from the "encrypted" data, without the key. Indeed, there is no key, but rather a complex dictionary transformation.

- A "backdoor" is merely teaching GCHQ to speak English. Sounds perfectly reasonable in your example.

I'd argue the exact problem is that politicians have the particular understanding of encryption that you just gave.

You need to communicate two things:

1) Why backdooring safe encryption irreversibly breaks it for everybody

2) Why that's a bad thing

Guys, both of you are behaving like non-tech people are idiots. They are as smart as you. They often have college degrees. Even children understand perfectly well what encryption is. Boy/girl scouts go out of their way to teach it, etc.