Interesting, I hadn't thought of using the techniques of deterministic cryptocurrency wallets to solve this problem. I need to read more about exactly how they

Interesting, I hadn't thought of using the techniques of deterministic cryptocurrency wallets to solve this problem. I need to read more about exactly how they work. It is also easy to solve this simply using ECC and ECDH. I just wrote a scheme on the board in the office. It might have slightly larger data payload than the deterministic wallets approach.