Also, what do you say about somehow integrating this into Personal Messages? They can basically be delivered as links instead of encrypted text, but that requires good uptime.
I already asked the same question not long ago in this topic

After having some time thinking about it I think that moderators would also be able to read those messages,
unless message is created in that way that only one specific member can decrypt and open it.
This could really be interesting. But how?

An element had to be used that only the target user knew in order to access it.
But I'll think about it. Maybe I can come up with something that might work.