You need to go back further and research cybernetics. But to answer your immediate question from an old soul who lived during that time, PGP comes to mind immediately.

The reason it never really took off is because people are inherently lazy in both action and mind. The intellectual effort required to exchange keys and set up communication channels involved more discomfort than surrendering privacy.

A fundamental law of change management is that people only change when the discomfort of staying put exceeds the discomfort of moving on.

You either need to lower the discomfort barrier to change, or raise the discomfort of the status quo.

To answer your last question, I think we are indeed in a cryptography renaissance, but it's out of necessity. The math is there for quantum proof cryptography, but I suspect the machines are about to take over the next phase of development because it exceeds our human capacity for mathematics.