What key? Sibling languages, alternative alphabets, and unconventional word choices don't have a key. If they want to learn shorthand, they can take a course at the community college like everybody else.
I never said anything about hiding my phone. I DO routinely encrypt data going in and out of my phone and some of the data is encrypted at rest. Nothing nefarious there, it just means that I use WhatsApp, Signal, and a web browser. Also SSH.
I guess if they want to go on a fishing expedition, they're SOL. If they have an actual good reason to suspect me personally of a crime, I guess they'll have a look at the phone. It would be nice if we could rely on law enforcement to not go on fishing expeditions and on judges to not approve of them (given that they are against the law), but here we are.