If you consider this "the" fundamental problem you're (a) underestimating the severity of other problems and (b) wildly overestimating what technology can achieve for humanity.
Trusting other individuals in this world is not a problem that's solvable by messaging protocols. Even literal scifi solutions like Mission Impossible exploding sunglasses inherently trust the recipient of the message not to share data post-self-destruct. Recipient trust is a fundamentally implicit part of deciding to communicate at all, through any medium.
If you consider this "the" fundamental problem you're (a) underestimating the severity of other problems and (b) wildly overestimating what technology can achieve for humanity.
Trusting other individuals in this world is not a problem that's solvable by messaging protocols. Even literal scifi solutions like Mission Impossible exploding sunglasses inherently trust the recipient of the message not to share data post-self-destruct. Recipient trust is a fundamentally implicit part of deciding to communicate at all, through any medium.