like, if I send the QR code to someone I want to talk to via email, anyone intercepting this message will at the very least know my SimpleX address; same thing if I send it via messenger.
edit: let’s assume we don’t have an established and trusted channel. furthermore, they’re not expecting this info.
Well, there’s not much they can do with the QR code. You can deactivate it as soon as you’ve made contact and established proof of identity with the recipient.
But, if it was really important, there are cryptographic key-exchange protocols you can do even over an insecure connection. The Diffie-Hellman key exchange is one of them. Using something like that, you can derive a shared secret key even if someone’s listening.
But personally, I would just break it into two parts, and send one by email and one with pastebin’s “burn-after-read” option.