> Is there a quantum computing-proof encryption algorithm

This is still an area of active research. For instance, there are learning-with-errors-based cryptosystems: https://en.wikipedia.org/wiki/Learning_with_errors#Use_in_cr... But such systems are based on the assumption that "this type of problem is probably hard even with quantum computers". I believe we don't have anything more "quantum-proof" than that..

And of course, there are cryptosystems with unconditional security. Such as OTP.