I love the comment! Thank you some_furry. You're a quick code reader.

You're correct that it doesn't offer key rotation or forward secrecy. That's something I definitely want to add (assuming anybody actually finds this service useful).

> One thing I didn't see was message padding of location data prior to encryption, to prevent side-channel attacks via ciphertext length. [7] I don't know if I missed this, or if it was omitted.

You didn't miss it. It's not there. It's something I should add.