Signal+ app idea. Use camera on phone to detect picture taking of phone screen + OS secure re no screenshots OR Personalized iris dependent refractive mapped contact lens that have your encryption key embedded across surface of lens. Only trusted people can see the msgs...
if you want to go really hard — there’s that great qualia computing post on embedding messages in light trials you can only see on certain psychoactive compoundshttps://qualiacomputing.com/2015/05/22/how-to-secretly-communicate-with-people-on-lsd/amp/ …
